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Arkhipov DV, Lomin SN, Romanov GA. A Model of the Full-Length Cytokinin Receptor: New Insights and Prospects. Int J Mol Sci 2023; 25:73. [PMID: 38203244 PMCID: PMC10779265 DOI: 10.3390/ijms25010073] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2023] [Revised: 12/11/2023] [Accepted: 12/15/2023] [Indexed: 01/12/2024] Open
Abstract
Cytokinins (CK) are one of the most important classes of phytohormones that regulate a wide range of processes in plants. A CK receptor, a sensor hybrid histidine kinase, was discovered more than 20 years ago, but the structural basis for its signaling is still a challenge for plant biologists. To date, only two fragments of the CK receptor structure, the sensory module and the receiver domain, were experimentally resolved. Some other regions were built up by molecular modeling based on structures of proteins homologous to CK receptors. However, in the long term, these data have proven insufficient for solving the structure of the full-sized CK receptor. The functional unit of CK receptor is the receptor dimer. In this article, a molecular structure of the dimeric form of the full-length CK receptor based on AlphaFold Multimer and ColabFold modeling is presented for the first time. Structural changes of the receptor upon interacting with phosphotransfer protein are visualized. According to mathematical simulation and available data, both types of dimeric receptor complexes with hormones, either half- or fully liganded, appear to be active in triggering signals. In addition, the prospects of using this and similar models to address remaining fundamental problems of CK signaling were outlined.
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Affiliation(s)
| | | | - Georgy A. Romanov
- Timiryazev Institute of Plant Physiology, Russian Academy of Sciences, Botanicheskaya 35, 127276 Moscow, Russia; (D.V.A.); (S.N.L.)
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2
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Mansour KE, Qi Y, Yan M, Ramström O, Priebe GP, Schaefers MM. Small-molecule activators of a bacterial signaling pathway inhibit virulence. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.12.02.569726. [PMID: 38076823 PMCID: PMC10705554 DOI: 10.1101/2023.12.02.569726] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/18/2023]
Abstract
The Burkholderia genus encompasses multiple human pathogens, including potential bioterrorism agents, that are often extensively antibiotic resistant. The FixLJ pathway in Burkholderia is a two-component system that regulates virulence. Previous work showed that fixLJ mutations arising during chronic infection confer increased virulence while decreasing the activity of the FixLJ pathway. We hypothesized that small-molecule activators of the FixLJ pathway could serve as anti-virulence therapies. Here, we developed a high-throughput assay that screened over 28,000 compounds and identified 11 that could specifically active the FixLJ pathway. Eight of these compounds, denoted Burkholderia Fix Activator (BFA) 1-8, inhibited the intracellular survival of Burkholderia in THP-1-dervived macrophages in a fixLJ-dependent manner without significant toxicity. One of the compounds, BFA1, inhibited the intracellular survival in macrophages of multiple Burkholderia species. Predictive modeling of the interaction of BFA1 with Burkholderia FixL suggests that BFA1 binds to the putative ATP/ADP binding pocket in the kinase domain, indicating a potential mechanism for pathway activation. These results indicate that small-molecule FixLJ pathway activators are promising anti-virulence agents for Burkholderia and define a new paradigm for antibacterial therapeutic discovery.
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Affiliation(s)
- Kathryn E. Mansour
- Division of Critical Care Medicine, Department of Anesthesiology, Critical Care and Pain Medicine, Boston Children’s Hospital; Boston, MA, USA
| | - Yunchuan Qi
- Department of Chemistry, University of Massachusetts Lowell, One University Ave., Lowell, MA 01854
| | - Mingdi Yan
- Department of Chemistry, University of Massachusetts Lowell, One University Ave., Lowell, MA 01854
| | - Olof Ramström
- Department of Chemistry, University of Massachusetts Lowell, One University Ave., Lowell, MA 01854
- Department of Chemistry and Biomedical Sciences, Linnaeus University, SE-39182 Kalmar, Sweden
| | - Gregory P. Priebe
- Division of Critical Care Medicine, Department of Anesthesiology, Critical Care and Pain Medicine, Boston Children’s Hospital; Boston, MA, USA
- Department of Anaesthesia, Harvard Medical School; Boston, MA, USA
| | - Matthew M. Schaefers
- Division of Critical Care Medicine, Department of Anesthesiology, Critical Care and Pain Medicine, Boston Children’s Hospital; Boston, MA, USA
- Department of Anaesthesia, Harvard Medical School; Boston, MA, USA
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3
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Sankhe GD, Raja R, Singh DP, Bheemireddy S, Rana S, Athira PJ, Dixit NM, Saini DK. Sequestration of histidine kinases by non-cognate response regulators establishes a threshold level of stimulation for bacterial two-component signaling. Nat Commun 2023; 14:4483. [PMID: 37491529 PMCID: PMC10368727 DOI: 10.1038/s41467-023-40095-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2020] [Accepted: 07/12/2023] [Indexed: 07/27/2023] Open
Abstract
Bacterial two-component systems (TCSs) consist of a sensor histidine kinase (HK) that perceives a specific signal, and a cognate response regulator (RR) that modulates the expression of target genes. Positive autoregulation improves TCS sensitivity to stimuli, but may trigger disproportionately large responses to weak signals, compromising bacterial fitness. Here, we combine experiments and mathematical modelling to reveal a general design that prevents such disproportionate responses: phosphorylated HKs (HK~Ps) can be sequestered by non-cognate RRs. We study five TCSs of Mycobacterium tuberculosis and find, for all of them, non-cognate RRs that show higher affinity than cognate RRs for HK~Ps. Indeed, in vitro assays show that HK~Ps preferentially bind higher affinity non-cognate RRs and get sequestered. Mathematical modelling indicates that this sequestration would introduce a 'threshold' stimulus strength for eliciting responses, thereby preventing responses to weak signals. Finally, we construct tunable expression systems in Mycobacterium bovis BCG to show that higher affinity non-cognate RRs suppress responses in vivo.
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Affiliation(s)
- Gaurav D Sankhe
- Centre for Biosystems Science and Engineering, Indian Institute of Science, Bengaluru, India
| | - Rubesh Raja
- Department of Chemical Engineering, Indian Institute of Science, Bengaluru, India
| | - Devendra Pratap Singh
- Department of Developmental Biology and Genetics, Indian Institute of Science, Bengaluru, India
| | - Sneha Bheemireddy
- Molecular Biophysics Unit, Indian Institute of Science, Bengaluru, India
| | - Subinoy Rana
- Materials Research Centre, Indian Institute of Science, Bengaluru, India
| | - P J Athira
- Department of Developmental Biology and Genetics, Indian Institute of Science, Bengaluru, India
| | - Narendra M Dixit
- Centre for Biosystems Science and Engineering, Indian Institute of Science, Bengaluru, India.
- Department of Chemical Engineering, Indian Institute of Science, Bengaluru, India.
| | - Deepak Kumar Saini
- Centre for Biosystems Science and Engineering, Indian Institute of Science, Bengaluru, India.
- Department of Developmental Biology and Genetics, Indian Institute of Science, Bengaluru, India.
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4
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Römling U, Cao LY, Bai FW. Evolution of cyclic di-GMP signalling on a short and long term time scale. MICROBIOLOGY (READING, ENGLAND) 2023; 169:001354. [PMID: 37384391 PMCID: PMC10333796 DOI: 10.1099/mic.0.001354] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/17/2023] [Accepted: 06/13/2023] [Indexed: 07/01/2023]
Abstract
Diversifying radiation of domain families within specific lineages of life indicates the importance of their functionality for the organisms. The foundation for the diversifying radiation of the cyclic di-GMP signalling network that occurred within the bacterial kingdom is most likely based in the outmost adaptability, flexibility and plasticity of the system. Integrative sensing of multiple diverse extra- and intracellular signals is made possible by the N-terminal sensory domains of the modular cyclic di-GMP turnover proteins, mutations in the protein scaffolds and subsequent signal reception by diverse receptors, which eventually rewires opposite host-associated as well as environmental life styles including parallel regulated target outputs. Natural, laboratory and microcosm derived microbial variants often with an altered multicellular biofilm behaviour as reading output demonstrated single amino acid substitutions to substantially alter catalytic activity including substrate specificity. Truncations and domain swapping of cyclic di-GMP signalling genes and horizontal gene transfer suggest rewiring of the network. Presence of cyclic di-GMP signalling genes on horizontally transferable elements in particular observed in extreme acidophilic bacteria indicates that cyclic di-GMP signalling and biofilm components are under selective pressure in these types of environments. On a short and long term evolutionary scale, within a species and in families within bacterial orders, respectively, the cyclic di-GMP signalling network can also rapidly disappear. To investigate variability of the cyclic di-GMP signalling system on various levels will give clues about evolutionary forces and discover novel physiological and metabolic pathways affected by this intriguing second messenger signalling system.
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Affiliation(s)
- Ute Römling
- Department of Microbiology, Tumor and Cell Biology, Biomedicum, Karolinska Institutet, Stockholm, Sweden
| | - Lian-Ying Cao
- Department of Microbiology, Tumor and Cell Biology, Biomedicum, Karolinska Institutet, Stockholm, Sweden
- State Key Laboratory of Microbial Metabolism, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, PR China
| | - Feng-Wu Bai
- State Key Laboratory of Microbial Metabolism, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, PR China
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5
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Structural features discriminating hybrid histidine kinase Rec domains from response regulator homologs. Nat Commun 2023; 14:1002. [PMID: 36864019 PMCID: PMC9981736 DOI: 10.1038/s41467-023-36597-8] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2022] [Accepted: 02/07/2023] [Indexed: 03/04/2023] Open
Abstract
In two-component systems, the information gathered by histidine kinases (HKs) are relayed to cognate response regulators (RRs). Thereby, the phosphoryl group of the auto-phosphorylated HK is transferred to the receiver (Rec) domain of the RR to allosterically activate its effector domain. In contrast, multi-step phosphorelays comprise at least one additional Rec (Recinter) domain that is typically part of the HK and acts as an intermediary for phosphoryl-shuttling. While RR Rec domains have been studied extensively, little is known about discriminating features of Recinter domains. Here we study the Recinter domain of the hybrid HK CckA by X-ray crystallography and NMR spectroscopy. Strikingly, all active site residues of the canonical Rec-fold are pre-arranged for phosphoryl-binding and BeF3- binding does not alter secondary or quaternary structure, indicating the absence of allosteric changes, the hallmark of RRs. Based on sequence-covariation and modeling, we analyze the intra-molecular DHp/Rec association in hybrid HKs.
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6
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Mutant structure of metabolic switch protein in complex with monomeric c-di-GMP reveals a potential mechanism of protein-mediated ligand dimerization. Sci Rep 2023; 13:2727. [PMID: 36810577 PMCID: PMC9944927 DOI: 10.1038/s41598-023-29110-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2022] [Accepted: 01/30/2023] [Indexed: 02/24/2023] Open
Abstract
Bacterial second messengers c-di-GMP and (p)ppGpp have broad functional repertoires ranging from growth and cell cycle control to the regulation of biofilm formation and virulence. The recent identification of SmbA, an effector protein from Caulobacter crescentus that is jointly targeted by both signaling molecules, has opened up studies on how these global bacterial networks interact. C-di-GMP and (p)ppGpp compete for the same SmbA binding site, with a dimer of c-di-GMP inducing a conformational change that involves loop 7 of the protein that leads to downstream signaling. Here, we report a crystal structure of a partial loop 7 deletion mutant, SmbA∆loop in complex with c-di-GMP determined at 1.4 Å resolution. SmbA∆loop binds monomeric c-di-GMP indicating that loop 7 is required for c-di-GMP dimerization. Thus the complex probably represents the first step of consecutive c-di-GMP binding to form an intercalated dimer as has been observed in wild-type SmbA. Considering the prevalence of intercalated c-di-GMP molecules observed bound to proteins, the proposed mechanism may be generally applicable to protein-mediated c-di-GMP dimerization. Notably, in the crystal, SmbA∆loop forms a 2-fold symmetric dimer via isologous interactions with the two symmetric halves of c-di-GMP. Structural comparisons of SmbA∆loop with wild-type SmbA in complex with dimeric c-di-GMP or ppGpp support the idea that loop 7 is critical for SmbA function by interacting with downstream partners. Our results also underscore the flexibility of c-di-GMP, to allow binding to the symmetric SmbA∆loop dimer interface. It is envisaged that such isologous interactions of c-di-GMP could be observed in hitherto unrecognized targets.
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7
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Wu S, Yang S, Wang M, Song N, Feng J, Wu H, Yang A, Liu C, Li Y, Guo F, Qiao J. Quorum sensing-based interactions among drugs, microbes, and diseases. SCIENCE CHINA. LIFE SCIENCES 2023; 66:137-151. [PMID: 35933489 DOI: 10.1007/s11427-021-2121-0] [Citation(s) in RCA: 10] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/20/2022] [Accepted: 05/02/2022] [Indexed: 02/04/2023]
Abstract
Many diseases and health conditions are closely related to various microbes, which participate in complex interactions with diverse drugs; nonetheless, the detailed targets of such drugs remain to be elucidated. Many existing studies have reported causal associations among drugs, gut microbes, or diseases, calling for a workflow to reveal their intricate interactions. In this study, we developed a systematic workflow comprising three modules to construct a Quorum Sensing-based Drug-Microbe-Disease (QS-DMD) database ( http://www.qsdmd.lbci.net/ ), which includes diverse interactions for more than 8,000 drugs, 163 microbes, and 42 common diseases. Potential interactions between microbes and more than 8,000 drugs have been systematically studied by targeting microbial QS receptors combined with a docking-based virtual screening technique and in vitro experimental validations. Furthermore, we have constructed a QS-based drug-receptor interaction network, proposed a systematic framework including various drug-receptor-microbe-disease connections, and mapped a paradigmatic circular interaction network based on the QS-DMD, which can provide the underlying QS-based mechanisms for the reported causal associations. The QS-DMD will promote an understanding of personalized medicine and the development of potential therapies for diverse diseases. This work contributes to a paradigm for the construction of a molecule-receptor-microbe-disease interaction network for human health that may form one of the key knowledge maps of precision medicine in the future.
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Affiliation(s)
- Shengbo Wu
- School of Chemical Engineering and Technology, Tianjin University, Tianjin, 300072, China.,State Key Laboratory of Chemical Engineering, Tianjin University, Tianjin, 300072, China.,Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), Tianjin, 300072, China
| | - Shujuan Yang
- School of Chemical Engineering and Technology, Tianjin University, Tianjin, 300072, China
| | - Manman Wang
- School of Chemical Engineering and Technology, Tianjin University, Tianjin, 300072, China
| | - Nan Song
- School of Computer Science and Technology, College of Intelligence and Computing, Tianjin University, Tianjin, 300350, China
| | - Jie Feng
- School of Computer Science and Technology, College of Intelligence and Computing, Tianjin University, Tianjin, 300350, China
| | - Hao Wu
- Institute of Shaoxing, Tianjin University, Shaoxing, 312300, China
| | - Aidong Yang
- Department of Engineering Science, University of Oxford, Oxford, OX1 3PJ, UK
| | - Chunjiang Liu
- School of Chemical Engineering and Technology, Tianjin University, Tianjin, 300072, China.,State Key Laboratory of Chemical Engineering, Tianjin University, Tianjin, 300072, China.,Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), Tianjin, 300072, China
| | - Yanni Li
- School of Chemical Engineering and Technology, Tianjin University, Tianjin, 300072, China. .,Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), Tianjin, 300072, China. .,Key Laboratory of Systems Bioengineering, Ministry of Education (Tianjin University), Tianjin, 300072, China.
| | - Fei Guo
- School of Computer Science and Engineering, Central South University, Changsha, 410083, China.
| | - Jianjun Qiao
- School of Chemical Engineering and Technology, Tianjin University, Tianjin, 300072, China. .,Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), Tianjin, 300072, China. .,Key Laboratory of Systems Bioengineering, Ministry of Education (Tianjin University), Tianjin, 300072, China. .,Institute of Shaoxing, Tianjin University, Shaoxing, 312300, China.
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8
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Wang L, Fan R, Li Z, Wang L, Bai X, Bu T, Dong Y, Xu Y, Quan C. Insights into the structure and function of the histidine kinase ComP from Bacillus amyloliquefaciens based on molecular modeling. Biosci Rep 2022; 42:BSR20220352. [PMID: 36052710 PMCID: PMC9620489 DOI: 10.1042/bsr20220352] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2022] [Revised: 08/01/2022] [Accepted: 09/01/2022] [Indexed: 11/21/2022] Open
Abstract
The ComPA two-component signal transduction system (TCS) is essential in Bacillus spp. However, the molecular mechanism of the histidine kinase ComP remains unclear. Here, we predicted the structure of ComP from Bacillus amyloliquefaciens Q-426 (BaComP) using an artificial intelligence approach, analyzed the structural characteristics based on the molecular docking results and compared homologous proteins, and then investigated the biochemical properties of BaComP. We obtained a truncated ComPS protein with high purity and correct folding in solution based on the predicted structures. The expression and purification of BaComP proteins suggested that the subdomains in the cytoplasmic region influenced the expression and stability of the recombinant proteins. ComPS is a bifunctional enzyme that exhibits the activity of both histidine kinase and phosphotransferase. We found that His571 played an obligatory role in the autophosphorylation of BaComP based on the analysis of the structures and mutagenesis studies. The molecular docking results suggested that the HATPase_c domain contained an ATP-binding pocket, and the ATP molecule was coordinated by eight conserved residues from the N, G1, and G2 boxes. Our study provides novel insight into the histidine kinase BaComP and its homologous proteins.
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Affiliation(s)
- Lulu Wang
- School of Life Science and Biotechnology, Dalian University of Technology, No. 2 Linggong Road, Dalian 116024, Liaoning, China
- Key Laboratory of Biotechnology and Bioresources Utilization of Ministry of Education, College of Life Science, Dalian Minzu University, China
| | - Ruochen Fan
- School of Life Science and Biotechnology, Dalian University of Technology, No. 2 Linggong Road, Dalian 116024, Liaoning, China
- Key Laboratory of Biotechnology and Bioresources Utilization of Ministry of Education, College of Life Science, Dalian Minzu University, China
| | - Zhuting Li
- Key Laboratory of Biotechnology and Bioresources Utilization of Ministry of Education, College of Life Science, Dalian Minzu University, China
- Department of Bioengineering, College of Life Science, Dalian Minzu University, Dalian 116600, Liaoning, China
| | - Lina Wang
- Institute of Cancer Stem Cell, Dalian Medical University, 9 Western Lvshun Road, Dalian 116044, Liaoning, China
| | - Xue Bai
- Key Laboratory of Biotechnology and Bioresources Utilization of Ministry of Education, College of Life Science, Dalian Minzu University, China
- Department of Bioengineering, College of Life Science, Dalian Minzu University, Dalian 116600, Liaoning, China
| | - Tingting Bu
- Key Laboratory of Biotechnology and Bioresources Utilization of Ministry of Education, College of Life Science, Dalian Minzu University, China
- Department of Bioengineering, College of Life Science, Dalian Minzu University, Dalian 116600, Liaoning, China
| | - Yuesheng Dong
- School of Life Science and Biotechnology, Dalian University of Technology, No. 2 Linggong Road, Dalian 116024, Liaoning, China
| | - Yongbin Xu
- Key Laboratory of Biotechnology and Bioresources Utilization of Ministry of Education, College of Life Science, Dalian Minzu University, China
- Department of Bioengineering, College of Life Science, Dalian Minzu University, Dalian 116600, Liaoning, China
| | - Chunshan Quan
- Key Laboratory of Biotechnology and Bioresources Utilization of Ministry of Education, College of Life Science, Dalian Minzu University, China
- Department of Bioengineering, College of Life Science, Dalian Minzu University, Dalian 116600, Liaoning, China
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Dual Regulatory Role Exerted by Cyclic Dimeric GMP To Control FsnR-Mediated Bacterial Swimming. mBio 2022; 13:e0141422. [PMID: 36069448 DOI: 10.1128/mbio.01414-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Bacterial motility has great medical and ecological significance because of its essential role in bacterial survival and pathogenesis. Cyclic dimeric GMP (c-di-GMP), a second messenger in bacteria, is the predominant regulator of flagellar synthesis and motility and possesses turnover mechanisms that have been thoroughly investigated. Therefore, much attention has been focused on identifying the upstream stimulatory signals and downstream modules that respond to altered c-di-GMP levels. Here, we systematically analyzed c-di-GMP cyclases and phosphodiesterases in Stenotrophomonas maltophilia to screen for motility regulators. Of these enzymes, we identified and characterized a new phosphodiesterase named SisP, which was found to facilitate bacterial swimming upon stimulation with ferrous iron. SisP-mediated degradation of c-di-GMP leads to FsnR-dependent transcription of flagellar genes. Remarkably, c-di-GMP controls FsnR via two independent mechanisms: by direct binding and indirectly by modulating its phosphorylation state. In this study, we deciphered a novel "one stone, two birds" regulatory strategy of c-di-GMP and uncovered the signal that stimulates c-di-GMP hydrolysis. Facilitation of bacterial swimming motility by ferrous iron might contribute to the higher risk of bacterial infection in acutely ill patients. IMPORTANCE Stenotrophomonas maltophilia has become a great threat to human health because of the high mortality of infected patients. Swimming motility plays a crucial role in regulating bacterial virulence and adaptation. However, limited progress has been made in cyclic dimeric GMP (c-di-GMP) controlling swimming motility of S. maltophilia. Here, we characterized c-di-GMP turnover enzymes encoded by S. maltophilia and dissected the regulatory details of a phosphodiesterase named SisP. We demonstrated that SisP degrades c-di-GMP to fully activate FsnR through directly releasing FsnR from the FsnR-c-di-GMP complex and indirectly increasing its phosphorylation level. This finding uncovered a quantitative, rather than an on-off, regulatory manner employed by c-di-GMP to regulate activities of its effectors. Identification of the specific activation of SisP by ferrous iron proposes SisP as a putative drug-target for controlling bacterial infection and ferrous iron at the wounds or cuts as a putative factor contributing to the higher risk of bacterial infection.
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The Histidine Kinase CckA Is Directly Inhibited by a Response Regulator-like Protein in a Negative Feedback Loop. mBio 2022; 13:e0148122. [PMID: 35876508 PMCID: PMC9430884 DOI: 10.1128/mbio.01481-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
In alphaproteobacteria, the two-component system (TCS) formed by the hybrid histidine kinase CckA, the phosphotransfer protein ChpT, and the response regulator CtrA is widely distributed. In these microorganisms, this system controls diverse functions such as motility, DNA repair, and cell division. In Caulobacterales and Rhizobiales, CckA is regulated by the pseudo- histidine kinase DivL, and the response regulator DivK. However, this regulatory circuit differs for other bacterial groups. For instance, in Rhodobacterales, DivK is absent and DivL consists of only the regulatory PAS domain. In this study, we report that, in Rhodobacter sphaeroides, the kinase activity of CckA is inhibited by Osp, a single domain response regulator (SDRR) protein that directly interacts with the transmitter domain of CckA. In vitro, the kinase activity of CckA was severely inhibited with an equimolar amount of Osp, whereas the phosphatase activity of CckA was not affected. We also found that the expression of osp is activated by CtrA creating a negative feedback loop. However, under growth conditions known to activate the TCS, the increased expression of osp does not parallel Osp accumulation, indicating a complex regulation. Phylogenetic analysis of selected species of Rhodobacterales revealed that Osp is widely distributed in several genera. For most of these species, we found a sequence highly similar to the CtrA-binding site in the control region of osp, suggesting that the TCS CckA/ChpT/CtrA is controlled by a novel regulatory circuit that includes Osp in these bacteria. IMPORTANCE The two-component systems (TCS) in bacteria in its simplest architecture consist of a histidine kinase (HK) and a response regulator (RR). In response to a specific stimulus, the HK is activated and drives phosphorylation of the RR, which is responsible of generating an adaptive response. These systems are ubiquitous among bacteria and are frequently controlled by accessory proteins. In alphaproteobacteria, the TCS formed by the HK CckA, the phosphotransferase ChpT, and the RR CtrA is widely distributed. Currently, most of the information of this system and its regulatory proteins comes from findings carried out in microorganisms where it is essential. However, this is not the case in many species, and studies of this TCS and its regulatory proteins are lacking. In this study, we found that Osp, a RR-like protein, inhibits the kinase activity of CckA in a negative feedback loop since osp expression is activated by CtrA. The inhibitory role of Osp and the similar action of the previously reported FixT protein, suggests the existence of a new group of RR-like proteins whose main function is to interact with the HK and prevent its phosphorylation.
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11
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Computational modeling of unphosphorylated CtrA: Cori binding in the Caulobacter cell cycle. iScience 2021; 24:103413. [PMID: 34901785 PMCID: PMC8640480 DOI: 10.1016/j.isci.2021.103413] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2021] [Revised: 09/17/2021] [Accepted: 11/05/2021] [Indexed: 02/04/2023] Open
Abstract
In the alphaproteobacterium, Caulobacter crescentus, phosphorylated CtrA (CtrA∼P), a master regulatory protein, binds directly to the chromosome origin (Cori) to inhibit DNA replication. Using a mathematical model of CtrA binding at Cori site [d], we provide computational evidence that CtrAU can displace CtrA∼P from Cori at the G1-S transition. Investigation of this interaction within a detailed model of the C. crescentus cell cycle suggests that CckA phosphatase may clear Cori of CtrA∼P by altering the [CtrAU]/[CtrA∼P] ratio rather than by completely depleting CtrA∼P. Model analysis reveals that the mechanism allows for a speedier transition into S phase, stabilizes the timing of chromosome replication under fluctuating rates of CtrA proteolysis, and may contribute to the viability of numerous mutant strains. Overall, these results suggest that CtrAU enhances the robustness of chromosome replication. More generally, our proposed regulation of CtrA:Cori dynamics may represent a novel motif for molecular signaling in cell physiology.
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Diversity in Sensing and Signaling of Bacterial Sensor Histidine Kinases. Biomolecules 2021; 11:biom11101524. [PMID: 34680156 PMCID: PMC8534201 DOI: 10.3390/biom11101524] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2021] [Revised: 10/13/2021] [Accepted: 10/13/2021] [Indexed: 11/17/2022] Open
Abstract
Two-component signal transduction systems (TCSs) are widely conserved in bacteria to respond to and adapt to the changing environment. Since TCSs are also involved in controlling the expression of virulence, biofilm formation, quorum sensing, and antimicrobial resistance in pathogens, they serve as candidates for novel drug targets. TCSs consist of a sensor histidine kinase (HK) and its cognate response regulator (RR). Upon perception of a signal, HKs autophosphorylate their conserved histidine residues, followed by phosphotransfer to their partner RRs. The phosphorylated RRs mostly function as transcriptional regulators and control the expression of genes necessary for stress response. HKs sense their specific signals not only in their extracytoplasmic sensor domain but also in their cytoplasmic and transmembrane domains. The signals are sensed either directly or indirectly via cofactors and accessory proteins. Accumulating evidence shows that a single HK can sense and respond to multiple signals in different domains. The underlying molecular mechanisms of how HK activity is controlled by these signals have been extensively studied both biochemically and structurally. In this article, we introduce the wide diversity of signal perception in different domains of HKs, together with their recently clarified structures and molecular mechanisms.
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13
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Waturuocha UW, Krishna MS, Malhotra V, Dixit NM, Saini DK. A Low-Prevalence Single-Nucleotide Polymorphism in the Sensor Kinase PhoR in Mycobacterium tuberculosis Suppresses Its Autophosphatase Activity and Reduces Pathogenic Fitness: Implications in Evolutionary Selection. Front Microbiol 2021; 12:724482. [PMID: 34512602 PMCID: PMC8424205 DOI: 10.3389/fmicb.2021.724482] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2021] [Accepted: 07/30/2021] [Indexed: 12/30/2022] Open
Abstract
The genome sequencing of Mycobacterium tuberculosis, the causative organism of tuberculosis, has significantly improved our understanding of the mechanisms that drive the establishment of infection and disease progression. Several clinical strains of M. tuberculosis exhibit single-nucleotide polymorphisms (SNPs), the implications of which are only beginning to be understood. Here, we examined the impact of a specific polymorphism in PhoR, the sensor kinase of the PhoPR two-component system. Biochemical analysis revealed reduced autophosphatase/ATPase activity, which led to enhanced downstream gene expression. We complemented M. tuberculosis H37Ra with the wild-type and mutant phoPR genes and characterized the strains in a cell line infection model. We provide an explanation for the low prevalence of the SNP in clinical strains (∼1%), as the mutation causes a survival disadvantage in the host cells. The study provides a rare example of selection of a signaling node under competing evolutionary forces, wherein a biochemically superior mutation aids bacterial adaptation within-host but has low fitness for infection and hence is not selected. Our study highlights the importance of accounting for such SNPs to test therapeutic and co-therapeutic methods to combat TB.
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Affiliation(s)
- Uchenna Watson Waturuocha
- Department of Studies in Zoology, University of Mysore, Mysore, India.,Department of Molecular Reproduction Development and Genetics, Indian Institute of Science, Bengaluru, India
| | - M S Krishna
- Department of Studies in Zoology, University of Mysore, Mysore, India
| | | | - Narendra M Dixit
- Department of Chemical Engineering, Indian Institute of Science, Bengaluru, India.,Center for Biosystems Science and Engineering, Indian Institute of Science, Bengaluru, India
| | - Deepak Kumar Saini
- Department of Molecular Reproduction Development and Genetics, Indian Institute of Science, Bengaluru, India.,Center for Biosystems Science and Engineering, Indian Institute of Science, Bengaluru, India
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14
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Abstract
Microbially produced indole metabolites serve as a diverse family of interspecies and interkingdom signaling molecules in the context of human health, crop production, and antibiotic resistance. We mined the protein database for sensors of indole metabolites and developed a biosensor for indole-3-aldehyde (I3A). Microbially produced I3A has been associated with reducing inflammation in diseases such as ulcerative colitis by stimulating the aryl hydrocarbon receptor pathway. We engineered an E. coli strain embedded with a single plasmid carrying a chimeric two-component system that detects I3A. Our I3A receptor characterization confirmed binding site residues that contribute to the sensor's I3A detection range of 0.1-10 μM. This new I3A biosensor opens the door to sensing indole metabolites produced at various host-microbe interfaces and provides new parts for synthetic biology applications.
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Affiliation(s)
- Jiefei Wang
- Department of Chemistry, University of Pittsburgh, 219 Parkman Avenue, Pittsburgh, Pennsylvania 15260, United States
| | - Chao Zhang
- Department of Chemistry, University of Pittsburgh, 219 Parkman Avenue, Pittsburgh, Pennsylvania 15260, United States
| | - W. Seth Childers
- Department of Chemistry, University of Pittsburgh, 219 Parkman Avenue, Pittsburgh, Pennsylvania 15260, United States
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15
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Hariharan VN, Yadav R, Thakur C, Singh A, Gopinathan R, Singh DP, Sankhe G, Malhotra V, Chandra N, Bhatt A, Saini DK. Cyclic di-GMP sensing histidine kinase PdtaS controls mycobacterial adaptation to carbon sources. FASEB J 2021; 35:e21475. [PMID: 33772870 DOI: 10.1096/fj.202002537rr] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2020] [Revised: 02/09/2021] [Accepted: 02/10/2021] [Indexed: 11/11/2022]
Abstract
Cell signaling relies on second messengers to transduce signals from the sensory apparatus to downstream signaling pathway components. In bacteria, one of the most important and ubiquitous second messenger is the small molecule cyclic diguanosine monophosphate (c-di-GMP). While the biosynthesis, degradation, and regulatory pathways controlled by c-di-GMP are well characterized, the mechanisms through which c-di-GMP controls these processes are not entirely understood. Herein we present the report of a c-di-GMP sensing sensor histidine kinase PdtaS (Rv3220c), which binds to c-di-GMP at submicromolar concentrations, subsequently perturbing signaling of the PdtaS-PdtaR (Rv1626) two-component system. Aided by biochemical analysis, genetics, molecular docking, FRET microscopy, and structural modelling, we have characterized the binding of c-di-GMP in the GAF domain of PdtaS. We show that a pdtaS knockout in Mycobacterium smegmatis is severely compromised in growth on amino acid deficient media and exhibits global transcriptional dysregulation. The perturbation of the c-di-GMP-PdtaS-PdtaR axis results in a cascade of cellular changes recorded by a multiparametric systems' approach of transcriptomics, unbiased metabolomics, and lipid analyses.
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Affiliation(s)
- Vignesh Narayan Hariharan
- Department of Molecular Reproduction, Development and Genetics, Indian Institute of Science, Bangalore, India
| | - Rahul Yadav
- Department of Molecular Reproduction, Development and Genetics, Indian Institute of Science, Bangalore, India
| | - Chandrani Thakur
- Department of Biochemistry, Indian Institute of Science, Bangalore, India
| | - Albel Singh
- School of Biosciences and Institute of Microbiology and Infection, University of Birmingham, Birmingham, UK
| | - Renu Gopinathan
- Department of Molecular Reproduction, Development and Genetics, Indian Institute of Science, Bangalore, India
| | - Devendra Pratap Singh
- Department of Molecular Reproduction, Development and Genetics, Indian Institute of Science, Bangalore, India
| | - Gaurav Sankhe
- Centre for Biosystems Science and Engineering, Indian Institute of Science, Bangalore, India
| | - Vandana Malhotra
- Department of Biochemistry, Sri Venkateswara College, Delhi University, Delhi, India
| | - Nagasuma Chandra
- Department of Biochemistry, Indian Institute of Science, Bangalore, India
| | - Apoorva Bhatt
- School of Biosciences and Institute of Microbiology and Infection, University of Birmingham, Birmingham, UK
| | - Deepak Kumar Saini
- Department of Molecular Reproduction, Development and Genetics, Indian Institute of Science, Bangalore, India.,Centre for Biosystems Science and Engineering, Indian Institute of Science, Bangalore, India
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16
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Egbert M, Porter KA, Ghani U, Kotelnikov S, Nguyen T, Ashizawa R, Kozakov D, Vajda S. Conservation of binding properties in protein models. Comput Struct Biotechnol J 2021; 19:2549-2566. [PMID: 34025942 PMCID: PMC8114079 DOI: 10.1016/j.csbj.2021.04.048] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2021] [Revised: 04/19/2021] [Accepted: 04/22/2021] [Indexed: 01/09/2023] Open
Abstract
We study the models submitted to round 12 of the Critical Assessment of protein Structure Prediction (CASP) experiment to assess how well the binding properties are conserved when the X-ray structures of the target proteins are replaced by their models. To explore small molecule binding we generate distributions of molecular probes - which are fragment-sized organic molecules of varying size, shape, and polarity - around the protein, and count the number of interactions between each residue and the probes, resulting in a vector of interactions we call a binding fingerprint. The similarity between two fingerprints, one for the X-ray structure and the other for a model of the protein, is determined by calculating the correlation coefficient between the two vectors. The resulting correlation coefficients are shown to correlate with global measures of accuracy established in CASP, and the relationship yields an accuracy threshold that has to be reached for meaningful binding surface conservation. The clusters formed by the probe molecules reliably predict binding hot spots and ligand binding sites in both X-ray structures and reasonably accurate models of the target, but ensembles of models may be needed for assessing the availability of proper binding pockets. We explored ligand docking to the few targets that had bound ligands in the X-ray structure. More targets were available to assess the ability of the models to reproduce protein-protein interactions by docking both the X-ray structures and models to their interaction partners in complexes. It was shown that this application is more difficult than finding small ligand binding sites, and the success rates heavily depend on the local structure in the potential interface. In particular, predicted conformations of flexible loops are frequently incorrect in otherwise highly accurate models, and may prevent predicting correct protein-protein interactions.
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Affiliation(s)
- Megan Egbert
- Department of Biomedical Engineering, Boston University, Boston, MA 02215, United States
| | - Kathryn A. Porter
- Department of Biomedical Engineering, Boston University, Boston, MA 02215, United States
| | - Usman Ghani
- Department of Biomedical Engineering, Boston University, Boston, MA 02215, United States
| | - Sergei Kotelnikov
- Department of Applied Mathematics and Statistics, Stony Brook University, Stony Brook, NY 11794, United States
- Laufer Center for Physical and Quantitative Biology, Stony Brook University, Stony Brook, NY 11794, United States
| | - Thu Nguyen
- Laufer Center for Physical and Quantitative Biology, Stony Brook University, Stony Brook, NY 11794, United States
| | - Ryota Ashizawa
- Department of Applied Mathematics and Statistics, Stony Brook University, Stony Brook, NY 11794, United States
- Laufer Center for Physical and Quantitative Biology, Stony Brook University, Stony Brook, NY 11794, United States
| | - Dima Kozakov
- Department of Applied Mathematics and Statistics, Stony Brook University, Stony Brook, NY 11794, United States
- Laufer Center for Physical and Quantitative Biology, Stony Brook University, Stony Brook, NY 11794, United States
| | - Sandor Vajda
- Department of Biomedical Engineering, Boston University, Boston, MA 02215, United States
- Department of Chemistry, Boston University, Boston, MA 02215, United States
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17
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Molecular switch architecture determines response properties of signaling pathways. Proc Natl Acad Sci U S A 2021; 118:2013401118. [PMID: 33688042 DOI: 10.1073/pnas.2013401118] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Many intracellular signaling pathways are composed of molecular switches, proteins that transition between two states-on and off Typically, signaling is initiated when an external stimulus activates its cognate receptor that, in turn, causes downstream switches to transition from off to on using one of the following mechanisms: activation, in which the transition rate from the off state to the on state increases; derepression, in which the transition rate from the on state to the off state decreases; and concerted, in which activation and derepression operate simultaneously. We use mathematical modeling to compare these signaling mechanisms in terms of their dose-response curves, response times, and abilities to process upstream fluctuations. Our analysis elucidates several operating principles for molecular switches. First, activation increases the sensitivity of the pathway, whereas derepression decreases sensitivity. Second, activation generates response times that decrease with signal strength, whereas derepression causes response times to increase with signal strength. These opposing features allow the concerted mechanism to not only show dose-response alignment, but also to decouple the response time from stimulus strength. However, these potentially beneficial properties come at the expense of increased susceptibility to upstream fluctuations. We demonstrate that these operating principles also hold when the models are extended to include additional features, such as receptor removal, kinetic proofreading, and cascades of switches. In total, we show how the architecture of molecular switches govern their response properties. We also discuss the biological implications of our findings.
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18
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Ashok N, He K, Bauer CE. No Light, No Germination: Excitation of the Rhodospirillum centenum Photosynthetic Apparatus Is Necessary and Sufficient for Cyst Germination. mBio 2021; 12:e03619-20. [PMID: 33727361 PMCID: PMC8092318 DOI: 10.1128/mbio.03619-20] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2021] [Accepted: 01/11/2021] [Indexed: 01/05/2023] Open
Abstract
Rhodospirillum centenum is a Gram-negative alphaproteobacterium that is capable of differentiating into dormant cysts that are metabolically inactive and desiccation resistant. Like spores synthesized by many Gram-positive species, dormant R. centenum cysts germinate in response to an environmental signal, indicating that conditions favor survival and proliferation. Factors that induce germination are called germinants and are often both niche and species specific. In this study, we have identified photosynthesis as a niche-specific germinant for R. centenum cyst germination. Specifically, excitation of wild-type cysts suspended in a nutrient-free buffer with far-red light at >750 nm results in rapid germination. This is in stark contrast to mutant strains deficient in photosynthesis that fail to germinate upon exposure to far-red light under all assayed conditions. We also show that photosynthesis-induced germination occurs in a carbon- and nitrogen-free buffer even in strains that are deficient in carbon or nitrogen fixation. These results demonstrate that photosynthesis not only is necessary for germination but is itself sufficient for the germination of R. centenum cysts.IMPORTANCE Environmental cues that signal Gram-positive spores to germinate (termed germinants) have been identified for several Bacillus and Clostridium species. These studies showed that germinants are niche and species specific. For example, Clostridium difficile spores sense bile salts as a germinant as their presence informs these cells of an intestinal environment. Bacillus fastidiosus spores use uric acid as a germinant that is present in soil and poultry litter as this species inhabits poultry litter. It is evident from these studies that dormant cells sample their environment to assess whether conditions are advantageous for the propagation and survival of vegetative cells. To date, a limited number of germinants have been defined for only a few Gram-positive spore-forming species. Beyond that group, there is scant information on what cues signal dormant cells to exit dormancy. In our study, we show that the versatile Gram-negative photosynthetic bacterium Rhodospirillum centenum uses light-driven photosynthesis, and not the availability of nutrients, to trigger the germination of dormant cysts. This use of light-driven photosynthesis as a germinant is surprising as this species is also capable of growing under dark conditions using exogenous carbon sources for energy. Consequently, photosynthetic growth appears to be the preferred growth mechanism by this species.
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Affiliation(s)
- Nandhini Ashok
- Department of Biology, Indiana University, Bloomington, Indiana, USA
| | - Kuang He
- Department of Molecular and Cellular Biochemistry, Indiana University, Bloomington, Indiana, USA
| | - Carl E Bauer
- Department of Molecular and Cellular Biochemistry, Indiana University, Bloomington, Indiana, USA
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19
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The CckA-ChpT-CtrA Phosphorelay Controlling Rhodobacter capsulatus Gene Transfer Agent Production Is Bidirectional and Regulated by Cyclic di-GMP. J Bacteriol 2021; 203:JB.00525-20. [PMID: 33288624 DOI: 10.1128/jb.00525-20] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2020] [Accepted: 12/03/2020] [Indexed: 12/15/2022] Open
Abstract
Protein phosphorylation is a universal mechanism for transducing cellular signals in prokaryotes and eukaryotes. The histidine kinase CckA, the histidine phosphotransferase ChpT, and the response regulator CtrA are conserved throughout the alphaproteobacteria. In Rhodobacter capsulatus, these proteins are key regulators of the gene transfer agent (RcGTA), which is present in several alphaproteobacteria. Using purified recombinant R. capsulatus proteins, we show in vitro autophosphorylation of CckA protein, and phosphotransfer to ChpT and thence to CtrA, to demonstrate biochemically that they form a phosphorelay. The secondary messenger cyclic di-GMP changed CckA from a kinase to a phosphatase, resulting in reversal of the phosphotransfer flow in the relay. The substitutions of two residues in CckA greatly affected the kinase or phosphatase activity of the protein in vitro, and production of mutant CckA proteins in vivo confirmed the importance of kinase but not phosphatase activity for the lytic release of RcGTA. However, phosphatase activity was needed to produce functional RcGTA particles. The binding of cyclic di-GMP to the wild-type and mutant CckA proteins was evaluated directly using a pulldown assay based on biotinylated cyclic di-GMP and streptavidin-linked beads.IMPORTANCE The CckA, ChpT, and CtrA phosphorelay proteins are widespread in the alphaproteobacteria, and there are two groups of organisms that differ in terms of whether this pathway is essential for cell viability. Little is known about the biochemical function of these proteins in organisms where the pathway is not essential, a group that includes Rhodobacter capsulatus This work demonstrates biochemically that CckA, ChpT, and CtrA also form a functional phosphorelay in the latter group and that the direction of phosphotransfer is reversed by cyclic di-GMP. It is important to improve understanding of more representatives of this pathway in order to obtain deeper insight into the function, composition, and evolutionary significance of a wider range of bacterial regulatory networks.
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20
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Czieborowski M, Hübenthal A, Poehlein A, Vogt I, Philipp B. Genetic and physiological analysis of biofilm formation on different plastic surfaces by Sphingomonas sp. strain S2M10 reveals an essential function of sphingan biosynthesis. MICROBIOLOGY-SGM 2020; 166:918-935. [PMID: 32762802 DOI: 10.1099/mic.0.000961] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Alphaproteobacteria belonging to the group of the sphingomonads are frequently found in biofilms colonizing pure-water systems, where they cause technical and hygienic problems. In this study, physiological properties of sphingomonads for biofilm formation on plastic surfaces were analysed. Sphingomonas sp. strain S2M10 was isolated from a used water-filtration membrane and submitted to transposon mutagenesis for isolating mutants with altered biofilm formation. Mutants showing strongly decreased biofilm formation carried transposon insertions in genes for the biosynthesis of the polysaccharide sphingan and for flagellar motility. Flagella-mediated attachment was apparently important for biofilm formation on plastic materials of intermediate hydrophobicity, while a mutant with defect in spnB, encoding the first enzyme in sphingan biosynthesis, showed no biofilm formation on all tested materials. Sphingan-dependent biofilm formation was induced in the presence of specific carbon sources while it was not induced in complex medium with yeast extract and tryptone. The regulation of sphingan-based biofilm formation was investigated by interfering with the CckA/ChpT/CtrA phosphorelay, a central signal-transduction pathway in most Alphaproteobacteria. Construction and ectopic expression of a kinase-deficient histidine kinase CckA caused cell elongation and massive sphingan-dependent cell aggregation. In addition, it caused increased activity of the promotor of spnB. In conclusion, these results indicate that sphingan-based biofilm formation by sphingomonads might be triggered by specific carbon sources under prototrophic conditions resembling a milieu that often prevails in pure-water systems.
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Affiliation(s)
- Michael Czieborowski
- Westfälische Wilhelms-Universität Münster, Institut für Molekulare Mikrobiologie und Biotechnologie, Corrensstr. 3, 48149 Münster, Germany
| | - Anna Hübenthal
- Present address: Institute for Technical Microbiology, Mannheim University of Applied Sciences, Mannheim, Germany.,Westfälische Wilhelms-Universität Münster, Institut für Molekulare Mikrobiologie und Biotechnologie, Corrensstr. 3, 48149 Münster, Germany
| | - Anja Poehlein
- Georg-August-Universität Göttingen, Department of Genomic and Applied Microbiology, Wilhelmsplatz 1, 37073 Göttingen, Germany
| | - Ines Vogt
- Westfälische Wilhelms-Universität Münster, Institut für Molekulare Mikrobiologie und Biotechnologie, Corrensstr. 3, 48149 Münster, Germany
| | - Bodo Philipp
- Westfälische Wilhelms-Universität Münster, Institut für Molekulare Mikrobiologie und Biotechnologie, Corrensstr. 3, 48149 Münster, Germany
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21
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Xie M, Wu M, Han A. Structural insights into the signal transduction mechanism of the K +-sensing two-component system KdpDE. Sci Signal 2020; 13:13/643/eaaz2970. [PMID: 32753477 DOI: 10.1126/scisignal.aaz2970] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Two-component systems (TCSs), which consist of a histidine kinase (HK) sensor and a response regulator (RR), are important for bacteria to quickly sense and respond to various environmental signals. HKs and RRs typically function as a cognate pair, interacting only with one another to transduce signaling. Precise signal transduction in a TCS depends on the specific interactions between the receiver domain (RD) of the RR and the dimerization and histidine phosphorylation domain (DHp) of the HK. Here, we determined the complex structure of KdpDE, a TCS consisting of the HK KdpD and the RR KdpE, which is responsible for K+ homeostasis. Both the RD and the DNA binding domain (DBD) of KdpE interacted with KdpD. Although the RD of KdpE and the DHp of KdpD contributed to binding specificity, the DBD mediated a distinct interaction with the catalytic ATP-binding (CA) domain of KdpD that was indispensable for KdpDE-mediated signal transduction. Moreover, the DBD-CA interface largely overlapped with that of the DBD-DNA complex, leading to competition between KdpD and its target promoter in a KdpE phosphorylation-dependent manner. In addition, the extended C-terminal tail of the CA domain was critical for stabilizing the interaction with KdpDE and for signal transduction. Together, these data provide a molecular basis for specific KdpD and KdpE interactions that play key roles in efficient signal transduction and transcriptional regulation by this TCS.
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Affiliation(s)
- Mingquan Xie
- State Key Laboratory of Cellular Stress Biology, School of Life Sciences, Xiamen University, Xiamen 361102, China
| | - Mengyuan Wu
- State Key Laboratory of Cellular Stress Biology, School of Life Sciences, Xiamen University, Xiamen 361102, China
| | - Aidong Han
- State Key Laboratory of Cellular Stress Biology, School of Life Sciences, Xiamen University, Xiamen 361102, China.
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22
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Kowallis KA, Silfani EM, Kasumu AP, Rong G, So V, Childers WS. Synthetic Control of Signal Flow Within a Bacterial Multi-Kinase Network. ACS Synth Biol 2020; 9:1705-1713. [PMID: 32559383 DOI: 10.1021/acssynbio.0c00043] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The signal processing capabilities of bacterial signaling networks offer immense potential for advanced phospho-signaling systems for synthetic biology. Emerging models suggest that complex development may require interconnections between what were once thought to be isolated signaling arrays. For example, Caulobacter crescentus achieves the feat of asymmetric division by utilizing a novel pseudokinase DivL, which senses the output of one signaling pathway to modulate a second pathway. It has been proposed that DivL reverses signal flow by exploiting conserved kinase conformational changes and protein-protein interactions. We engineered a series of DivL-based modulators to synthetically stimulate reverse signaling of the network in vivo. Stimulation of conformational changes through the DivL signal transmission helix resulted in changes to hallmark features of the network: C. crescentus motility and DivL accumulation at the cell poles. Additionally, mutations to a conserved PAS sensor transmission motif disrupted reverse signaling flow in vivo. We propose that synthetic stimulation and sensor disruption provide strategies to define signaling circuit organization principles for the rational design and validation of synthetic pathways.
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Affiliation(s)
- Kimberly A. Kowallis
- Department of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
| | - Elayna M. Silfani
- Department of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
| | - Amanda P. Kasumu
- Department of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
| | - Grace Rong
- Department of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
| | - Victor So
- Department of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
| | - W. Seth Childers
- Department of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
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23
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Duvall SW, Childers WS. Design of a Histidine Kinase FRET Sensor to Detect Complex Signal Integration within Living Bacteria. ACS Sens 2020; 5:1589-1596. [PMID: 32495620 DOI: 10.1021/acssensors.0c00008] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Histidine kinases (HK) switch between conformational states that promote kinase and phosphatase activities to regulate diverse cellular processes. Past studies have shown that these functional states can display heterogeneity between cells in microbial communities and can vary at the subcellular level. Methods to track and correlate the kinase conformational state with the phenotypic response of living bacteria cells will offer new opportunities to interrogate bacterial signaling mechanisms. As a proof of principle, we incorporated both mClover3 (donor) and mRuby3 (acceptor) fluorescent proteins into the Caulobacter crescentus cell-cycle HK CckA as an in vivo fluorescence resonance energy transfer (FRET) sensor to detect these structural changes. Our engineered FRET sensor was responsive to CckA-specific input signals and detected subcellular changes in CckA signal integration that occurs as cells develop. We demonstrated the potential of using the CckA FRET sensor as an in vivo screening tool for HK inhibitors. In summary, we have developed a new HK FRET sensor design strategy that can be adopted to monitor in vivo changes for interrogation of a broad range of signaling mechanisms in living bacteria.
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Affiliation(s)
- Samuel W. Duvall
- Department of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
| | - W. Seth Childers
- Department of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
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24
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Aline Dias da P, Nathalia Marins de A, Gabriel Guarany de A, Robson Francisco de S, Cristiane Rodrigues G. The World of Cyclic Dinucleotides in Bacterial Behavior. Molecules 2020; 25:molecules25102462. [PMID: 32466317 PMCID: PMC7288161 DOI: 10.3390/molecules25102462] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2019] [Revised: 03/05/2020] [Accepted: 03/17/2020] [Indexed: 02/07/2023] Open
Abstract
The regulation of multiple bacterial phenotypes was found to depend on different cyclic dinucleotides (CDNs) that constitute intracellular signaling second messenger systems. Most notably, c-di-GMP, along with proteins related to its synthesis, sensing, and degradation, was identified as playing a central role in the switching from biofilm to planktonic modes of growth. Recently, this research topic has been under expansion, with the discoveries of new CDNs, novel classes of CDN receptors, and the numerous functions regulated by these molecules. In this review, we comprehensively describe the three main bacterial enzymes involved in the synthesis of c-di-GMP, c-di-AMP, and cGAMP focusing on description of their three-dimensional structures and their structural similarities with other protein families, as well as the essential residues for catalysis. The diversity of CDN receptors is described in detail along with the residues important for the interaction with the ligand. Interestingly, genomic data strongly suggest that there is a tendency for bacterial cells to use both c-di-AMP and c-di-GMP signaling networks simultaneously, raising the question of whether there is crosstalk between different signaling systems. In summary, the large amount of sequence and structural data available allows a broad view of the complexity and the importance of these CDNs in the regulation of different bacterial behaviors. Nevertheless, how cells coordinate the different CDN signaling networks to ensure adaptation to changing environmental conditions is still open for much further exploration.
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25
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Novel Divisome-Associated Protein Spatially Coupling the Z-Ring with the Chromosomal Replication Terminus in Caulobacter crescentus. mBio 2020; 11:mBio.00487-20. [PMID: 32345642 PMCID: PMC7188993 DOI: 10.1128/mbio.00487-20] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Growing bacteria require careful tuning of cell division processes with dynamic organization of replicating chromosomes. In enteric bacteria, ZapA associates with the cytoskeletal Z-ring and establishes a physical linkage to the chromosomal replication terminus through its interaction with ZapB-MatP-DNA complexes. However, because ZapB and MatP are found only in enteric bacteria, it remains unclear how the Z-ring and the terminus are coordinated in the vast majority of bacteria. Here, we provide evidence that a novel conserved protein, termed ZapT, mediates colocalization of the Z-ring with the terminus in Caulobacter crescentus, a model organism that is phylogenetically distant from enteric bacteria. Given that ZapT facilitates cell division processes in C. crescentus, this study highlights the universal importance of the physical linkage between the Z-ring and the terminus in maintaining cell integrity. Cell division requires proper spatial coordination with the chromosome, which undergoes dynamic changes during chromosome replication and segregation. FtsZ is a bacterial cytoskeletal protein that assembles into the Z-ring, providing a platform to build the cell division apparatus. In the model bacterium Caulobacter crescentus, the cellular localization of the Z-ring is controlled during the cell cycle in a chromosome replication-coupled manner. Although dynamic localization of the Z-ring at midcell is driven primarily by the replication origin-associated FtsZ inhibitor MipZ, the mechanism ensuring accurate positioning of the Z-ring remains unclear. In this study, we showed that the Z-ring colocalizes with the replication terminus region, located opposite the origin, throughout most of the C. crescentus cell cycle. Spatial organization of the two is mediated by ZapT, a previously uncharacterized protein that interacts with the terminus region and associates with ZapA and ZauP, both of which are part of the incipient division apparatus. While the Z-ring and the terminus region coincided with the presence of ZapT, colocalization of the two was perturbed in cells lacking zapT, which is accompanied by delayed midcellular positioning of the Z-ring. Moreover, cells overexpressing ZapT showed compromised positioning of the Z-ring and MipZ. These findings underscore the important role of ZapT in controlling cell division processes. We propose that ZapT acts as a molecular bridge that physically links the terminus region to the Z-ring, thereby ensuring accurate site selection for the Z-ring. Because ZapT is conserved in proteobacteria, these findings may define a general mechanism coordinating cell division with chromosome organization.
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The CtrA Regulon of Rhodobacter sphaeroides Favors Adaptation to a Particular Lifestyle. J Bacteriol 2020; 202:JB.00678-19. [PMID: 31932315 DOI: 10.1128/jb.00678-19] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2019] [Accepted: 01/09/2020] [Indexed: 11/20/2022] Open
Abstract
Activation of the two-component system formed by CckA, ChpT, and CtrA (kinase, phosphotransferase, and response regulator, respectively) in Rhodobacter sphaeroides does not occur under the growth conditions commonly used in the laboratory. However, it is possible to isolate a gain-of-function mutant in CckA that turns the system on. Using massive parallel transcriptome sequencing (RNA-seq), we identified 321 genes that are differentially regulated by CtrA. From these genes, 239 were positively controlled and 82 were negatively regulated. Genes encoding the Fla2 polar flagella and gas vesicle proteins are strongly activated by CtrA. Genes involved in stress responses as well as several transcriptional factors are also positively controlled, whereas the photosynthetic and CO2 fixation genes are repressed. Potential CtrA-binding sites were bioinformatically identified, leading to the proposal that at least 81 genes comprise the direct regulon. Based on our results, we ponder that the transcriptional response orchestrated by CtrA enables a lifestyle in which R. sphaeroides will effectively populate the surface layer of a water body enabled by gas vesicles and will remain responsive to chemotactic stimuli using the chemosensoring system that controls the Fla2 flagellum. Simultaneously, fine-tuning of photosynthesis and stress responses will reduce the damage caused by heat and high light intensity in this water stratum. In summary, in this bacterium CtrA has evolved to control physiological responses that allow its adaptation to a particular lifestyle instead of controlling the cell cycle as occurs in other species.IMPORTANCE Cell motility in Alphaproteobacteria is frequently controlled by the CckA, ChpT, and CtrA two-component system. Under the growth conditions commonly used in the laboratory, ctrA is transcriptionally inactive in Rhodobacter sphaeroides, and motility depends on the Fla1 flagellar system that was acquired by a horizontal transfer event. Likely, the incorporation of this flagellar system released CtrA from the strong selective pressure of being the main motility regulator, allowing this two-component system to specialize and respond to some specific conditions. Identifying the genes that are directly regulated by CtrA could help us understand the conditions in which the products of this regulon are required. Massive parallel transcriptome sequencing (RNA-seq) revealed that CtrA orchestrates an adaptive response that contributes to the colonization of a particular environmental niche.
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Lasker K, von Diezmann L, Zhou X, Ahrens DG, Mann TH, Moerner WE, Shapiro L. Selective sequestration of signalling proteins in a membraneless organelle reinforces the spatial regulation of asymmetry in Caulobacter crescentus. Nat Microbiol 2020; 5:418-429. [PMID: 31959967 PMCID: PMC7549192 DOI: 10.1038/s41564-019-0647-7] [Citation(s) in RCA: 68] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2018] [Accepted: 11/25/2019] [Indexed: 12/16/2022]
Abstract
Selective recruitment and concentration of signalling proteins within membraneless compartments is a ubiquitous mechanism for subcellular organization1-3. The dynamic flow of molecules into and out of these compartments occurs on faster timescales than for membrane-enclosed organelles, presenting a possible mechanism to control spatial patterning within cells. Here, we combine single-molecule tracking and super-resolution microscopy, light-induced subcellular localization, reaction-diffusion modelling and a spatially resolved promoter activation assay to study signal exchange in and out of the 200 nm cytoplasmic pole-organizing protein popZ (PopZ) microdomain at the cell pole of the asymmetrically dividing bacterium Caulobacter crescentus4-8. Two phospho-signalling proteins, the transmembrane histidine kinase CckA and the cytoplasmic phosphotransferase ChpT, provide the only phosphate source for the cell fate-determining transcription factor CtrA9-18. We find that all three proteins exhibit restricted rates of entry into and escape from the microdomain as well as enhanced phospho-signalling within, leading to a submicron gradient of activated CtrA-P19 that is stable and sublinear. Entry into the microdomain is selective for cytosolic proteins and requires a binding pathway to PopZ. Our work demonstrates how nanoscale protein assemblies can modulate signal propagation with fine spatial resolution, and that in Caulobacter, this modulation serves to reinforce asymmetry and differential cell fate of the two daughter cells.
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Affiliation(s)
- Keren Lasker
- Department of Developmental Biology, Stanford University School of Medicine, Stanford, CA, USA
| | - Lexy von Diezmann
- Department of Chemistry, Stanford University, Stanford, CA, USA
- Center for Cell and Genome Science, University of Utah, Salt Lake City, UT, USA
- School of Biological Sciences, University of Utah, Salt Lake City, UT, USA
| | - Xiaofeng Zhou
- Department of Developmental Biology, Stanford University School of Medicine, Stanford, CA, USA
| | - Daniel G Ahrens
- Department of Developmental Biology, Stanford University School of Medicine, Stanford, CA, USA
| | - Thomas H Mann
- Department of Developmental Biology, Stanford University School of Medicine, Stanford, CA, USA
- NOMIS Center for Immunobiology and Microbial Pathogenesis, Salk Institute for Biological Studies, La Jolla, CA, USA
| | - W E Moerner
- Department of Chemistry, Stanford University, Stanford, CA, USA
| | - Lucy Shapiro
- Department of Developmental Biology, Stanford University School of Medicine, Stanford, CA, USA.
- Chan Zuckerberg Biohub, San Francisco, CA, USA.
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Gallagher KA, Schumacher MA, Bush MJ, Bibb MJ, Chandra G, Holmes NA, Zeng W, Henderson M, Zhang H, Findlay KC, Brennan RG, Buttner MJ. c-di-GMP Arms an Anti-σ to Control Progression of Multicellular Differentiation in Streptomyces. Mol Cell 2020; 77:586-599.e6. [PMID: 31810759 PMCID: PMC7005675 DOI: 10.1016/j.molcel.2019.11.006] [Citation(s) in RCA: 54] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2019] [Revised: 10/22/2019] [Accepted: 11/04/2019] [Indexed: 12/31/2022]
Abstract
Streptomyces are our primary source of antibiotics, produced concomitantly with the transition from vegetative growth to sporulation in a complex developmental life cycle. We previously showed that the signaling molecule c-di-GMP binds BldD, a master repressor, to control initiation of development. Here we demonstrate that c-di-GMP also intervenes later in development to control differentiation of the reproductive hyphae into spores by arming a novel anti-σ (RsiG) to bind and sequester a sporulation-specific σ factor (σWhiG). We present the structure of the RsiG-(c-di-GMP)2-σWhiG complex, revealing an unusual, partially intercalated c-di-GMP dimer bound at the RsiG-σWhiG interface. RsiG binds c-di-GMP in the absence of σWhiG, employing a novel E(X)3S(X)2R(X)3Q(X)3D motif repeated on each helix of a coiled coil. Further studies demonstrate that c-di-GMP is essential for RsiG to inhibit σWhiG. These findings reveal a newly described control mechanism for σ-anti-σ complex formation and establish c-di-GMP as the central integrator of Streptomyces development.
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Affiliation(s)
- Kelley A. Gallagher
- Department of Molecular Microbiology, John Innes Centre, Norwich Research Park, Norwich NR4 7UH, UK
| | - Maria A. Schumacher
- Department of Biochemistry, Duke University School of Medicine, Durham, NC 27710, USA,Corresponding author
| | - Matthew J. Bush
- Department of Molecular Microbiology, John Innes Centre, Norwich Research Park, Norwich NR4 7UH, UK
| | - Maureen J. Bibb
- Department of Molecular Microbiology, John Innes Centre, Norwich Research Park, Norwich NR4 7UH, UK
| | - Govind Chandra
- Department of Molecular Microbiology, John Innes Centre, Norwich Research Park, Norwich NR4 7UH, UK
| | - Neil A. Holmes
- Department of Molecular Microbiology, John Innes Centre, Norwich Research Park, Norwich NR4 7UH, UK
| | - Wenjie Zeng
- Department of Biochemistry, Duke University School of Medicine, Durham, NC 27710, USA
| | - Max Henderson
- Department of Biochemistry, Duke University School of Medicine, Durham, NC 27710, USA
| | - Hengshan Zhang
- Department of Biochemistry, Duke University School of Medicine, Durham, NC 27710, USA
| | - Kim C. Findlay
- Department of Cell and Developmental Biology, John Innes Centre, Norwich Research Park, Norwich NR4 7UH, UK
| | - Richard G. Brennan
- Department of Biochemistry, Duke University School of Medicine, Durham, NC 27710, USA
| | - Mark J. Buttner
- Department of Molecular Microbiology, John Innes Centre, Norwich Research Park, Norwich NR4 7UH, UK,Corresponding author
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Structural Conservation and Diversity of PilZ-Related Domains. J Bacteriol 2020; 202:JB.00664-19. [PMID: 31740493 DOI: 10.1128/jb.00664-19] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2019] [Accepted: 11/12/2019] [Indexed: 01/13/2023] Open
Abstract
The widespread bacterial second messenger cyclic diguanylate (c-di-GMP) regulates a variety of processes, including protein secretion, motility, cell development, and biofilm formation. c-di-GMP-dependent responses are often mediated by its binding to the cytoplasmic receptors that contain the PilZ domain. Here, we present comparative structural and sequence analysis of various PilZ-related domains and describe three principal types of them: (i) the canonical PilZ domain, whose structure includes a six-stranded beta-barrel and a C-terminal alpha helix, (ii) an atypical PilZ domain that contains two extra alpha helices and forms stable tetramers, and (iii) divergent PilZ-related domains, which include the eponymous PilZ protein and PilZN (YcgR_N) and PilZNR (YcgR_2) domains. We refine the second c-di-GMP binding motif of PilZ as [D/N]hSXXG and show that the hydrophobic residue h of this motif interacts with a cluster of conserved hydrophobic residues, helping maintain the PilZ domain fold. We describe several novel PilZN-type domains that are fused to the canonical PilZ domains in specific taxa, such as spirochetes, actinobacteria, aquificae, cellulose-degrading clostridia, and deltaproteobacteria. We propose that the evolution of the three major groups of PilZ domains included (i) fusion of pilZ with other genes, which produced Alg44, cellulose synthase, and other multidomain proteins; (ii) insertion of an ∼200-bp fragment, which resulted in the formation of tetramer-forming PilZ proteins; and (iii) tandem duplication of pilZ genes, which led to the formation of PilZ dimers and YcgR-like proteins.IMPORTANCE c-di-GMP is a ubiquitous bacterial second messenger that regulates motility, biofilm formation, and virulence of many bacterial pathogens. The PilZ domain is a widespread c-di-GMP receptor that binds c-di-GMP through its RXXXR and [D/N]hSXXG motifs; some PilZ domains lack these motifs and are unable to bind c-di-GMP. We used structural and sequence analysis to assess the diversity of PilZ-related domains and define their common features. We show that the hydrophobic residue h in the second position of the second motif is highly conserved; it may serve as a readout for c-di-GMP binding. We describe three principal classes of PilZ-related domains, canonical, tetramer-forming, and divergent PilZ domains, and propose the evolutionary pathways that led to the emergence of these PilZ types.
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Abstract
Prokaryotes commonly undergo genome reduction, particularly in the case of symbiotic bacteria. Genome reductions tend toward the energetically favorable removal of unnecessary, redundant, or nonfunctional genes. However, without mechanisms to compensate for these losses, deleterious mutation and genetic drift might otherwise overwhelm a population. Among the mechanisms employed to counter gene loss and share evolutionary success within a population, gene transfer agents (GTAs) are increasingly becoming recognized as important contributors. Although viral in origin, GTA particles package fragments of their "host" genome for distribution within a population of cells, often in a synchronized manner, rather than selfishly packaging genes necessary for their spread. Microbes as diverse as archaea and alpha-proteobacteria have been known to produce GTA particles, which are capable of transferring selective advantages such as virulence factors and antibiotic resistance. In this review, we discuss the various types of GTAs identified thus far, focusing on a defined set of symbiotic alpha-proteobacteria known to carry them. Drawing attention to the predicted presence of these genes, we discuss their potential within the selective marine and terrestrial environments occupied by mutualistic, parasitic, and endosymbiotic microbes.
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Affiliation(s)
- Steen Christensen
- Department of Biological Sciences, Florida International University, Miami, FL, USA.,Biomolecular Sciences Institute, Florida International University, Miami, FL, USA
| | - Laura R Serbus
- Department of Biological Sciences, Florida International University, Miami, FL, USA. .,Biomolecular Sciences Institute, Florida International University, Miami, FL, USA.
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31
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Hybrid histidine kinase activation by cyclic di-GMP-mediated domain liberation. Proc Natl Acad Sci U S A 2019; 117:1000-1008. [PMID: 31882446 PMCID: PMC6969517 DOI: 10.1073/pnas.1911427117] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
Expression of bacterial genes in response to various cues is predominantly regulated by 2- or multicomponent systems with autophosphorylation of a histidine kinase (HK), the first component, being controlled by an N-terminal sensor domain. This is followed by phosphotransfer to the receiver domain (Rec) of a cognate transcription factor. In about 20% of all cases, HK core and Rec are fused to form a hybrid HK (HHK). Here, we show the first full-length structure of an HHK and reveal how it gets activated by the second-messenger c-di-GMP that binds to a dedicated pseudo-Rec domain. The mechanism is fundamentally distinct from the canonical mechanism of HK regulation, but may be operational in many HHKs with a predicted pseudo-Rec domain. Cytosolic hybrid histidine kinases (HHKs) constitute major signaling nodes that control various biological processes, but their input signals and how these are processed are largely unknown. In Caulobacter crescentus, the HHK ShkA is essential for accurate timing of the G1-S cell cycle transition and is regulated by the corresponding increase in the level of the second messenger c-di-GMP. Here, we use a combination of X-ray crystallography, NMR spectroscopy, functional analyses, and kinetic modeling to reveal the regulatory mechanism of ShkA. In the absence of c-di-GMP, ShkA predominantly adopts a compact domain arrangement that is catalytically inactive. C-di-GMP binds to the dedicated pseudoreceiver domain Rec1, thereby liberating the canonical Rec2 domain from its central position where it obstructs the large-scale motions required for catalysis. Thus, c-di-GMP cannot only stabilize domain interactions, but also engage in domain dissociation to allosterically invoke a downstream effect. Enzyme kinetics data are consistent with conformational selection of the ensemble of active domain constellations by the ligand and show that autophosphorylation is a reversible process.
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32
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Ozaki S. Regulation of replication initiation: lessons from Caulobacter crescentus. Genes Genet Syst 2019; 94:183-196. [PMID: 31495806 DOI: 10.1266/ggs.19-00011] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Chromosome replication is a fundamental process in all domains of life. To accurately transmit genetic material to offspring, the initiation of chromosome replication is tightly regulated to ensure that it occurs only once in each cell division cycle. In the model bacterium Caulobacter crescentus, the CtrA response regulator inhibits the origin of replication at the pre-replication stage. Inactivation of CtrA permits the universal DnaA initiator to form an initiation complex at the origin, leading to replication initiation. Subsequently, the initiation complex is inactivated to prevent extra initiation. Whereas DNA replication occurs periodically in exponentially growing cells, replication initiation is blocked under various stress conditions to halt cell cycle progression until the normal condition is restored or the cells adapt to the stress. Thus, regulating the initiation complex plays an important role in not only driving cell cycle progression, but also maintaining cell integrity under stress. Multiple regulatory signaling pathways controlling CtrA and DnaA have been identified and recent studies have advanced our knowledge of the underlying mechanistic and molecular processes. This review focuses on how bacterial cells control replication initiation, highlighting the latest findings that have emerged from studies in C. crescentus.
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Affiliation(s)
- Shogo Ozaki
- Department of Molecular Biology, Graduate School of Pharmaceutical Sciences, Kyushu University
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33
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Cheng ST, Wang FF, Qian W. Cyclic-di-GMP binds to histidine kinase RavS to control RavS-RavR phosphotransfer and regulates the bacterial lifestyle transition between virulence and swimming. PLoS Pathog 2019; 15:e1007952. [PMID: 31408509 PMCID: PMC6707612 DOI: 10.1371/journal.ppat.1007952] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2018] [Revised: 08/23/2019] [Accepted: 06/30/2019] [Indexed: 12/28/2022] Open
Abstract
The two-component signalling system (TCS) comprising a histidine kinase (HK) and a response regulator (RR) is the predominant bacterial sense-and-response machinery. Because bacterial cells usually encode a number of TCSs to adapt to various ecological niches, the specificity of a TCS is in the centre of regulation. Specificity of TCS is defined by the capability and velocity of phosphoryl transfer between a cognate HK and a RR. Here, we provide genetic, enzymology and structural data demonstrating that the second messenger cyclic-di-GMP physically and specifically binds to RavS, a HK of the phytopathogenic, gram-negative bacterium Xanthomonas campestris pv. campestris. The [c-di-GMP]-RavS interaction substantially promotes specificity between RavS and RavR, a GGDEF–EAL domain-containing RR, by reinforcing the kinetic preference of RavS to phosphorylate RavR. [c-di-GMP]-RavS binding effectively decreases the phosphorylation level of RavS and negatively regulates bacterial swimming. Intriguingly, the EAL domain of RavR counteracts the above regulation by degrading c-di-GMP and then increasing the level of phosphorylated RavS. Therefore, RavR acts as a bifunctional phosphate sink that finely controls the level of phosphorylated RavS. These biochemical processes interactively modulate the phosphoryl flux between RavS-RavR and bacterial lifestyle transition. Our results revealed that c-di-GMP acts as an allosteric effector to dynamically modulate specificity between HK and RR. c-di-GMP is a multifunctional bacterial second messenger that controls various physiological processes. The nucleotide derivative binds to riboswitches or proteins as effectors during regulation. Here, we found that c-di-GMP physically binds to a histidine kinase, RavS, of a plant pathogenic bacterium. The binding event significantly enhanced the phosphotransferase activity of RavS to phosphorylate a response regulator, RavR. This process tightly modulates the phosphorylation level of RavS, which is important to the lifestyle transition of the bacterium between virulence and swimming motility. Therefore, our results reveal that c-di-GMP controls the bacterial two-component signalling, one of the dominant mechanisms of bacterial cells in adaptation to various environmental stimuli.
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Affiliation(s)
- Shou-Ting Cheng
- State Key Laboratory of Plant Genomics, Institution of Microbiology, Chinese Academy of Sciences, Beijing, China
- State Key Laboratory of Plant Genomics, Institution of Genetics and Development Biology, Chinese Academy of Sciences, Beijing, China
| | - Fang-Fang Wang
- State Key Laboratory of Plant Genomics, Institution of Microbiology, Chinese Academy of Sciences, Beijing, China
| | - Wei Qian
- State Key Laboratory of Plant Genomics, Institution of Microbiology, Chinese Academy of Sciences, Beijing, China
- College of Advanced Agricultural Sciences, University of Chinese Academy of Sciences, Beijing, China
- Center for Excellence in Biotic Interactions, Chinese Academy of Sciences, Beijing, China
- * E-mail:
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34
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Buschiazzo A, Trajtenberg F. Two-Component Sensing and Regulation: How Do Histidine Kinases Talk with Response Regulators at the Molecular Level? Annu Rev Microbiol 2019; 73:507-528. [PMID: 31226026 DOI: 10.1146/annurev-micro-091018-054627] [Citation(s) in RCA: 77] [Impact Index Per Article: 15.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Perceiving environmental and internal information and reacting in adaptive ways are essential attributes of living organisms. Two-component systems are relevant protein machineries from prokaryotes and lower eukaryotes that enable cells to sense and process signals. Implicating sensory histidine kinases and response regulator proteins, both components take advantage of protein phosphorylation and flexibility to switch conformations in a signal-dependent way. Dozens of two-component systems act simultaneously in any given cell, challenging our understanding about the means that ensure proper connectivity. This review dives into the molecular level, attempting to summarize an emerging picture of how histidine kinases and cognate response regulators achieve required efficiency, specificity, and directionality of signaling pathways, properties that rely on protein:protein interactions. α helices that carry information through long distances, the fine combination of loose and specific kinase/regulator interactions, and malleable reaction centers built when the two components meet emerge as relevant universal principles.
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Affiliation(s)
- Alejandro Buschiazzo
- Laboratory of Molecular and Structural Microbiology, Institut Pasteur de Montevideo, Montevideo 11400, Uruguay; , .,Integrative Microbiology of Zoonotic Agents, Department of Microbiology, Institut Pasteur, Paris 75015, France
| | - Felipe Trajtenberg
- Laboratory of Molecular and Structural Microbiology, Institut Pasteur de Montevideo, Montevideo 11400, Uruguay; ,
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35
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Francis VI, Porter SL. Multikinase Networks: Two-Component Signaling Networks Integrating Multiple Stimuli. Annu Rev Microbiol 2019; 73:199-223. [PMID: 31112439 DOI: 10.1146/annurev-micro-020518-115846] [Citation(s) in RCA: 42] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Bacteria depend on two-component systems to detect and respond to threats. Simple pathways comprise a single sensor kinase (SK) that detects a signal and activates a response regulator protein to mediate an appropriate output. These simple pathways with only a single SK are not well suited to making complex decisions where multiple different stimuli need to be evaluated. A recently emerging theme is the existence of multikinase networks (MKNs) where multiple SKs collaborate to detect and integrate numerous different signals to regulate a major lifestyle switch, e.g., between virulence, sporulation, biofilm formation, and cell division. In this review, the role of MKNs and the phosphosignaling mechanisms underpinning their signal integration and decision making are explored.
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Affiliation(s)
- Vanessa I Francis
- Biosciences, College of Life and Environmental Sciences, University of Exeter, Exeter EX4 4QD, United Kingdom; ,
| | - Steven L Porter
- Biosciences, College of Life and Environmental Sciences, University of Exeter, Exeter EX4 4QD, United Kingdom; ,
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36
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Abstract
Response regulators function as the output components of two-component systems, which couple the sensing of environmental stimuli to adaptive responses. Response regulators typically contain conserved receiver (REC) domains that function as phosphorylation-regulated switches to control the activities of effector domains that elicit output responses. This modular design is extremely versatile, enabling different regulatory strategies tuned to the needs of individual signaling systems. This review summarizes structural features that underlie response regulator function. An abundance of atomic resolution structures and complementary biochemical data have defined the mechanisms for response regulator enzymatic activities, revealed trends in regulatory strategies utilized by response regulators of different subfamilies, and provided insights into interactions of response regulators with their cognate histidine kinases. Among the hundreds of thousands of response regulators identified, variations abound. This article provides a framework for understanding structural features that enable function of canonical response regulators and a basis for distinguishing noncanonical configurations.
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Affiliation(s)
- Rong Gao
- Center for Advanced Biotechnology and Medicine, Department of Biochemistry and Molecular Biology, Rutgers-Robert Wood Johnson Medical School, Piscataway, New Jersey 08854, USA; , ,
| | - Sophie Bouillet
- Center for Advanced Biotechnology and Medicine, Department of Biochemistry and Molecular Biology, Rutgers-Robert Wood Johnson Medical School, Piscataway, New Jersey 08854, USA; , ,
| | - Ann M Stock
- Center for Advanced Biotechnology and Medicine, Department of Biochemistry and Molecular Biology, Rutgers-Robert Wood Johnson Medical School, Piscataway, New Jersey 08854, USA; , ,
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37
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Heindl JE, Crosby D, Brar S, Pinto JF, Singletary T, Merenich D, Eagan JL, Buechlein AM, Bruger EL, Waters CM, Fuqua C. Reciprocal control of motility and biofilm formation by the PdhS2 two-component sensor kinase of Agrobacterium tumefaciens. MICROBIOLOGY (READING, ENGLAND) 2019; 165:146-162. [PMID: 30620265 PMCID: PMC7003649 DOI: 10.1099/mic.0.000758] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/21/2018] [Accepted: 11/28/2018] [Indexed: 12/13/2022]
Abstract
A core regulatory pathway that directs developmental transitions and cellular asymmetries in Agrobacterium tumefaciens involves two overlapping, integrated phosphorelays. One of these phosphorelays putatively includes four histidine sensor kinase homologues, DivJ, PleC, PdhS1 and PdhS2, and two response regulators, DivK and PleD. In several different alphaproteobacteria, this pathway influences a conserved downstream phosphorelay that ultimately controls the phosphorylation state of the CtrA master response regulator. The PdhS2 sensor kinase reciprocally regulates biofilm formation and swimming motility. In the current study, the mechanisms by which the A. tumefaciens sensor kinase PdhS2 directs this regulation are delineated. PdhS2 lacking a key residue implicated in phosphatase activity is markedly deficient in proper control of attachment and motility phenotypes, whereas a kinase-deficient PdhS2 mutant is only modestly affected. A genetic interaction between DivK and PdhS2 is revealed, unmasking one of several connections between PdhS2-dependent phenotypes and transcriptional control by CtrA. Epistasis experiments suggest that PdhS2 may function independently of the CckA sensor kinase, the cognate sensor kinase for CtrA, which is inhibited by DivK. Global expression analysis of the pdhS2 mutant reveals a restricted regulon, most likely functioning through CtrA to separately control motility and regulate the levels of the intracellular signal cyclic diguanylate monophosphate (cdGMP), thereby affecting the production of adhesive polysaccharides and attachment. We hypothesize that in A. tumefaciens the CtrA regulatory circuit has expanded to include additional inputs through the addition of PdhS-type sensor kinases, likely fine-tuning the response of this organism to the soil microenvironment.
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Affiliation(s)
- Jason E. Heindl
- Department of Biology, Indiana University, Bloomington, IN 47405, USA
- Department of Biological Sciences, University of the Sciences in Philadelphia, Philadelphia, PA 19104, USA
| | - Daniel Crosby
- Department of Biological Sciences, University of the Sciences in Philadelphia, Philadelphia, PA 19104, USA
- Present address: Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, PA 15213, USA
| | - Sukhdev Brar
- Department of Biological Sciences, University of the Sciences in Philadelphia, Philadelphia, PA 19104, USA
| | - John F. Pinto
- Department of Biological Sciences, University of the Sciences in Philadelphia, Philadelphia, PA 19104, USA
| | - Tiyan Singletary
- Department of Biological Sciences, University of the Sciences in Philadelphia, Philadelphia, PA 19104, USA
| | - Daniel Merenich
- Department of Biological Sciences, University of the Sciences in Philadelphia, Philadelphia, PA 19104, USA
| | - Justin L. Eagan
- Department of Biology, Indiana University, Bloomington, IN 47405, USA
| | - Aaron M. Buechlein
- Center for Genomics and Bioinformatics, Indiana University, Bloomington, IN 47405, USA
| | - Eric L. Bruger
- Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, MI 48824, USA
- Present address: Department of Biological Sciences, University of Idaho, Moscow, ID 83844, USA
| | - Christopher M. Waters
- Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, MI 48824, USA
| | - Clay Fuqua
- Department of Biology, Indiana University, Bloomington, IN 47405, USA
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38
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Multilayered control of chromosome replication in Caulobacter crescentus. Biochem Soc Trans 2019; 47:187-196. [PMID: 30626709 PMCID: PMC6393856 DOI: 10.1042/bst20180460] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2018] [Revised: 12/11/2018] [Accepted: 12/12/2018] [Indexed: 12/24/2022]
Abstract
The environmental Alphaproteobacterium Caulobacter crescentus is a classical model to study the regulation of the bacterial cell cycle. It divides asymmetrically, giving a stalked cell that immediately enters S phase and a swarmer cell that stays in the G1 phase until it differentiates into a stalked cell. Its genome consists in a single circular chromosome whose replication is tightly regulated so that it happens only in stalked cells and only once per cell cycle. Imbalances in chromosomal copy numbers are the most often highly deleterious, if not lethal. This review highlights recent discoveries on pathways that control chromosome replication when Caulobacter is exposed to optimal or less optimal growth conditions. Most of these pathways target two proteins that bind directly onto the chromosomal origin: the highly conserved DnaA initiator of DNA replication and the CtrA response regulator that is found in most Alphaproteobacteria The concerted inactivation and proteolysis of CtrA during the swarmer-to-stalked cell transition license cells to enter S phase, while a replisome-associated Regulated Inactivation and proteolysis of DnaA (RIDA) process ensures that initiation starts only once per cell cycle. When Caulobacter is stressed, it turns on control systems that delay the G1-to-S phase transition or the elongation of DNA replication, most probably increasing its fitness and adaptation capacities.
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39
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Narayanan S, Kumar L, Radhakrishnan SK. Sensory domain of the cell cycle kinase CckA regulates the differential DNA binding of the master regulator CtrA in Caulobacter crescentus. BIOCHIMICA ET BIOPHYSICA ACTA. GENE REGULATORY MECHANISMS 2018; 1861:952-961. [PMID: 30496040 PMCID: PMC6169604 DOI: 10.1016/j.bbagrm.2018.08.006] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/26/2018] [Revised: 08/28/2018] [Accepted: 08/28/2018] [Indexed: 01/20/2023]
Abstract
Sophisticated signaling mechanisms allow bacterial cells to cope with environmental and intracellular challenges. Activation of specific pathways ameliorates these challenges and thereby warrants integrity. Here, we demonstrate the pliability of the CckA-CtrA two-component signaling system in the freshwater bacterium Caulobacter crescentus. Our forward genetic screen to analyze suppressor mutations that can negate the chromosome segregation block induced by the topoisomerase IV inhibitor, NstA, yielded various point mutations in the cell cycle histidine kinase, CckA. Notably, we identified a point mutation in the PAS-B domain of CckA, which resulted in increased levels of phosphorylated CtrA (CtrA~P), the master cell cycle regulator. Surprisingly, this increase in CtrA~P levels did not translate into a genome-wide increase in the DNA occupancy of CtrA, but specifically enriched its affinity for the chromosomal origin of replication, Cori, and for a very small sub-set of CtrA regulated promoters. We show that through this enhanced binding of CtrA to the Cori, cells are able to overcome the toxic defects rendered by stable NstA through a possible slow down in the chromosome replication cycle. Taken together, our work opens up an unexplored and intriguing aspect of the CckA-CtrA signal transduction pathway. The distinctive DNA binding nature of CtrA and its regulation by CckA might also be crucial for pathogenesis because of the highly conserved nature of the CckA-CtrA pathway in alphaproteobacteria.
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Affiliation(s)
- Sharath Narayanan
- School of Biology, Indian Institute of Science Education and Research, Thiruvananthapuram 695551, Kerala, India
| | - Lokesh Kumar
- School of Biology, Indian Institute of Science Education and Research, Thiruvananthapuram 695551, Kerala, India
| | - Sunish Kumar Radhakrishnan
- School of Biology, Indian Institute of Science Education and Research, Thiruvananthapuram 695551, Kerala, India.
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40
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Lomin SN, Myakushina YA, Kolachevskaya OO, Getman IA, Arkhipov DV, Savelieva EM, Osolodkin DI, Romanov GA. Cytokinin perception in potato: new features of canonical players. JOURNAL OF EXPERIMENTAL BOTANY 2018; 69:3839-3853. [PMID: 29800344 PMCID: PMC6054150 DOI: 10.1093/jxb/ery199] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/20/2017] [Accepted: 05/15/2018] [Indexed: 05/11/2023]
Abstract
Potato is the most economically important non-cereal food crop. Tuber formation in potato is regulated by phytohormones, cytokinins (CKs) in particular. The present work studied CK signal perception in potato. The sequenced potato genome of doubled monoploid Phureja was used for bioinformatic analysis and as a tool for identification of putative CK receptors from autotetraploid potato cv. Désirée. All basic elements of multistep phosphorelay required for CK signal transduction were identified in the Phureja genome, including three genes orthologous to three CK receptor genes (AHK 2-4) of Arabidopsis. As distinct from Phureja, autotetraploid potato contains at least two allelic isoforms of each receptor type. Putative receptor genes from Désirée plants were cloned, sequenced and expressed, and the main characteristics of encoded proteins were determined, in particular their consensus motifs, modelled structure, ligand-binding properties, and ability to transmit CK signals. In all studied aspects the predicted sensor histidine kinases met the requirements for genuine CK receptors. Expression of potato CK receptors was found to be organ-specific and sensitive to growth conditions, particularly to sucrose content. Our results provide a solid basis for further in-depth study of CK signaling system and biotechnological improvement of potato.
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Affiliation(s)
- Sergey N Lomin
- Timiryazev Institute of Plant Physiology, Russian Academy of Sciences, Moscow, Russia
| | - Yulia A Myakushina
- Timiryazev Institute of Plant Physiology, Russian Academy of Sciences, Moscow, Russia
| | | | - Irina A Getman
- Timiryazev Institute of Plant Physiology, Russian Academy of Sciences, Moscow, Russia
| | - Dmitry V Arkhipov
- Timiryazev Institute of Plant Physiology, Russian Academy of Sciences, Moscow, Russia
| | - Ekaterina M Savelieva
- Timiryazev Institute of Plant Physiology, Russian Academy of Sciences, Moscow, Russia
| | - Dmitry I Osolodkin
- Timiryazev Institute of Plant Physiology, Russian Academy of Sciences, Moscow, Russia
- Institute of Poliomyelitis and Viral Encephalitides, FSBSI Chumakov FSC R&D IBP RAS, Poselok Instituta Poliomelita 8 bd 1, Poselenie Moskovsky, Moscow, Russia
- Sechenov First Moscow State Medical University, Moscow, Russia
| | - Georgy A Romanov
- Timiryazev Institute of Plant Physiology, Russian Academy of Sciences, Moscow, Russia
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Leninskie Gory, Moscow, Russia
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41
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Abstract
Spatial control of intracellular signaling relies on signaling proteins sensing their subcellular environment. In many cases, a large number of upstream signals are funneled to a master regulator of cellular behavior, but it remains unclear how individual proteins can rapidly integrate a complex array of signals within the appropriate spatial niche within the cell. As a model for how subcellular spatial information can control signaling activity, we have reconstituted the cell pole-specific control of the master regulator kinase/phosphatase CckA from the asymmetrically dividing bacterium Caulobacter crescentus CckA is active as a kinase only when it accumulates within a microdomain at the new cell pole, where it colocalizes with the pseudokinase DivL. Both proteins contain multiple PAS domains, a multifunctional class of sensory domains present across the kingdoms of life. Here, we show that CckA uses its PAS domains to integrate information from DivL and its own oligomerization state to control the balance of its kinase and phosphatase activities. We reconstituted the DivL-CckA complex on liposomes in vitro and found that DivL directly controls the CckA kinase/phosphatase switch, and that stimulation of either CckA catalytic activity depends on the second of its two PAS domains. We further show that CckA oligomerizes through a multidomain interaction that is critical for stimulation of kinase activity by DivL, while DivL stimulation of CckA phosphatase activity is independent of CckA homooligomerization. Our results broadly demonstrate how signaling factors can leverage information from their subcellular niche to drive spatiotemporal control of cell signaling.
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42
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Opoku-Temeng C, Sintim HO. Targeting c-di-GMP Signaling, Biofilm Formation, and Bacterial Motility with Small Molecules. Methods Mol Biol 2018; 1657:419-430. [PMID: 28889311 DOI: 10.1007/978-1-4939-7240-1_31] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Bacteria possess several signaling molecules that regulate distinct phenotypes. Cyclic di-GMP (c-di-GMP) has emerged as a ubiquitous second messenger that regulates bacterial virulence, cell cycle, motility, and biofilm formation. The link between c-di-GMP signaling and biofilm formation affords novel strategies for treatment of biofilm-associated infections, which is a major public health problem. The complex c-di-GMP signaling pathway creates a hurdle in the development of small molecule modulators. Nonetheless, some progress has been made in this regard and inhibitors of c-di-GMP metabolizing enzymes that affect biofilm formation and motility have been documented. Herein we discuss the components of c-di-GMP signaling, their correlation with biofilm formation as well as motility and reported small molecule inhibitors of c-di-GMP signaling.
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Affiliation(s)
- Clement Opoku-Temeng
- Purdue Institute for Drug Discovery, Purdue University, 500 Oval Drive, West Lafayette, IN, 47907, USA.,Biochemistry Graduate Program, University of Maryland, College Park, MD, 20742, USA.,Department of Chemistry, Center for Drug Discovery, Purdue University, West Lafayette, IN, 47907, USA
| | - Herman O Sintim
- Purdue Institute for Drug Discovery, Purdue University, 500 Oval Drive, West Lafayette, IN, 47907, USA. .,Department of Chemistry, Purdue University, West Lafayette, IN, 47907, USA. .,Purdue Institute of Inflammation, Immunology and Infectious Disease, West Lafayette, IN, 47907, USA.
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43
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Wright GSA, Saeki A, Hikima T, Nishizono Y, Hisano T, Kamaya M, Nukina K, Nishitani H, Nakamura H, Yamamoto M, Antonyuk SV, Hasnain SS, Shiro Y, Sawai H. Architecture of the complete oxygen-sensing FixL-FixJ two-component signal transduction system. Sci Signal 2018; 11:11/525/eaaq0825. [PMID: 29636388 DOI: 10.1126/scisignal.aaq0825] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
The symbiotic nitrogen-fixing bacterium Bradyrhizobium japonicum is critical to the agro-industrial production of soybean because it enables the production of high yields of soybeans with little use of nitrogenous fertilizers. The FixL and FixJ two-component system (TCS) of this bacterium ensures that nitrogen fixation is only stimulated under conditions of low oxygen. When it is not bound to oxygen, the histidine kinase FixL undergoes autophosphorylation and transfers phosphate from adenosine triphosphate (ATP) to the response regulator FixJ, which, in turn, stimulates the expression of genes required for nitrogen fixation. We purified full-length B. japonicum FixL and FixJ proteins and defined their structures individually and in complex using small-angle x-ray scattering, crystallographic, and in silico modeling techniques. Comparison of active and inactive forms of FixL suggests that intramolecular signal transduction is driven by local changes in the sensor domain and in the coiled-coil region connecting the sensor and histidine kinase domains. We also found that FixJ exhibits conformational plasticity not only in the monomeric state but also in tetrameric complexes with FixL during phosphotransfer. This structural characterization of a complete TCS contributes both a mechanistic and evolutionary understanding to TCS signal relay, specifically in the context of the control of nitrogen fixation in root nodules.
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Affiliation(s)
- Gareth S A Wright
- Molecular Biophysics Group, Institute of Integrative Biology, Faculty of Health and Life Sciences, University of Liverpool, Liverpool L69 7ZB, UK
| | - Akane Saeki
- Graduate School of Life Science, University of Hyogo, 3-2-1 Kouto, Kamigori, Ako, Hyogo 678-1297, Japan
| | - Takaaki Hikima
- RIKEN SPring-8 Center, 1-1-1 Kouto, Sayo, Hyogo 679-5148, Japan
| | - Yoko Nishizono
- Graduate School of Life Science, University of Hyogo, 3-2-1 Kouto, Kamigori, Ako, Hyogo 678-1297, Japan
| | - Tamao Hisano
- RIKEN SPring-8 Center, 1-1-1 Kouto, Sayo, Hyogo 679-5148, Japan
| | - Misaki Kamaya
- Graduate School of Life Science, University of Hyogo, 3-2-1 Kouto, Kamigori, Ako, Hyogo 678-1297, Japan
| | - Kohei Nukina
- Graduate School of Life Science, University of Hyogo, 3-2-1 Kouto, Kamigori, Ako, Hyogo 678-1297, Japan
| | - Hideo Nishitani
- Graduate School of Life Science, University of Hyogo, 3-2-1 Kouto, Kamigori, Ako, Hyogo 678-1297, Japan
| | - Hiro Nakamura
- RIKEN SPring-8 Center, 1-1-1 Kouto, Sayo, Hyogo 679-5148, Japan
| | - Masaki Yamamoto
- RIKEN SPring-8 Center, 1-1-1 Kouto, Sayo, Hyogo 679-5148, Japan
| | - Svetlana V Antonyuk
- Molecular Biophysics Group, Institute of Integrative Biology, Faculty of Health and Life Sciences, University of Liverpool, Liverpool L69 7ZB, UK
| | - S Samar Hasnain
- Molecular Biophysics Group, Institute of Integrative Biology, Faculty of Health and Life Sciences, University of Liverpool, Liverpool L69 7ZB, UK
| | - Yoshitsugu Shiro
- Graduate School of Life Science, University of Hyogo, 3-2-1 Kouto, Kamigori, Ako, Hyogo 678-1297, Japan. .,RIKEN SPring-8 Center, 1-1-1 Kouto, Sayo, Hyogo 679-5148, Japan
| | - Hitomi Sawai
- Graduate School of Life Science, University of Hyogo, 3-2-1 Kouto, Kamigori, Ako, Hyogo 678-1297, Japan. .,RIKEN SPring-8 Center, 1-1-1 Kouto, Sayo, Hyogo 679-5148, Japan
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44
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Liu T, Ish‐Shalom S, Torng W, Lafita A, Bock C, Mort M, Cooper DN, Bliven S, Capitani G, Mooney SD, Altman RB. Biological and functional relevance of CASP predictions. Proteins 2018; 86 Suppl 1:374-386. [PMID: 28975675 PMCID: PMC5820171 DOI: 10.1002/prot.25396] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2017] [Revised: 09/12/2017] [Accepted: 10/03/2017] [Indexed: 02/06/2023]
Abstract
Our goal is to answer the question: compared with experimental structures, how useful are predicted models for functional annotation? We assessed the functional utility of predicted models by comparing the performances of a suite of methods for functional characterization on the predictions and the experimental structures. We identified 28 sites in 25 protein targets to perform functional assessment. These 28 sites included nine sites with known ligand binding (holo-sites), nine sites that are expected or suggested by experimental authors for small molecule binding (apo-sites), and Ten sites containing important motifs, loops, or key residues with important disease-associated mutations. We evaluated the utility of the predictions by comparing their microenvironments to the experimental structures. Overall structural quality correlates with functional utility. However, the best-ranked predictions (global) may not have the best functional quality (local). Our assessment provides an ability to discriminate between predictions with high structural quality. When assessing ligand-binding sites, most prediction methods have higher performance on apo-sites than holo-sites. Some servers show consistently high performance for certain types of functional sites. Finally, many functional sites are associated with protein-protein interaction. We also analyzed biologically relevant features from the protein assemblies of two targets where the active site spanned the protein-protein interface. For the assembly targets, we find that the features in the models are mainly determined by the choice of template.
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Affiliation(s)
- Tianyun Liu
- Department of BioengineeringStanford UniversityStanfordCalifornia
| | - Shirbi Ish‐Shalom
- Biomedical Informatics Training Program, Stanford UniversityStanfordCalifornia
| | - Wen Torng
- Department of BioengineeringStanford UniversityStanfordCalifornia
| | - Aleix Lafita
- Laboratory of Biomolecular ResearchPaul Scherrer InstituteVilligenSwitzerland
- Department of Biosystems Science and EngineeringETH Zurich4058BaselSwitzerland
| | - Christian Bock
- Department of Biomedical Informatics and Medical EducationUniversity of WashingtonSeattleWashington
- Heidelberg UniversityHeidelbergGermany
| | - Matthew Mort
- Institute of Medical Genetics, Cardiff UniversityUnited Kingdom
| | - David N Cooper
- Institute of Medical Genetics, Cardiff UniversityUnited Kingdom
| | - Spencer Bliven
- Laboratory of Biomolecular ResearchPaul Scherrer InstituteVilligenSwitzerland
- National Center for Biotechnology Information, National Library of MedicineNational Institutes of HealthBethesdaMaryland
| | - Guido Capitani
- Laboratory of Biomolecular ResearchPaul Scherrer InstituteVilligenSwitzerland
- Department of BiologyETH ZurichZurichSwitzerland
| | - Sean D. Mooney
- Department of Biomedical Informatics and Medical EducationUniversity of WashingtonSeattleWashington
| | - Russ B. Altman
- Department of BioengineeringStanford UniversityStanfordCalifornia
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45
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Liu Y, Rose J, Huang S, Hu Y, Wu Q, Wang D, Li C, Liu M, Zhou P, Jiang L. A pH-gated conformational switch regulates the phosphatase activity of bifunctional HisKA-family histidine kinases. Nat Commun 2017; 8:2104. [PMID: 29235472 PMCID: PMC5727384 DOI: 10.1038/s41467-017-02310-9] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2017] [Accepted: 11/20/2017] [Indexed: 01/01/2023] Open
Abstract
Histidine kinases are key regulators in the bacterial two-component systems that mediate the cellular response to environmental changes. The vast majority of the sensor histidine kinases belong to the bifunctional HisKA family, displaying both kinase and phosphatase activities toward their substrates. The molecular mechanisms regulating the opposing activities of these enzymes are not well understood. Through a combined NMR and crystallographic study on the histidine kinase HK853 and its response regulator RR468 from Thermotoga maritima, here we report a pH-mediated conformational switch of HK853 that shuts off its phosphatase activity under acidic conditions. Such a pH-sensing mechanism is further demonstrated in the EnvZ-OmpR two-component system from Salmonella enterica in vitro and in vivo, which directly contributes to the bacterial infectivity. Our finding reveals a broadly conserved mechanism that regulates the phosphatase activity of the largest family of bifunctional histidine kinases in response to the change of environmental pH. Bacteria adapt to changing environmental conditions through signal transduction mediated by the two-component system (TCS). Here, the authors combine X-ray crystallography and NMR studies to characterize a pH-gated conformational switch that regulates the phosphatase activity of TCS bifunctional histidine kinases.
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Affiliation(s)
- Yixiang Liu
- Key Laboratory of Magnetic Resonance in Biological Systems, State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, National Center for Magnetic Resonance in Wuhan, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan, 430071, China
| | - Joshua Rose
- Department of Biochemistry, Duke University Medical Center, Durham, NC, 27710, USA
| | - Shaojia Huang
- CAS Key Laboratory of Special Pathogens and Biosafety, Center for Emerging Infectious Diseases, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, 430071, China.,University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Yangbo Hu
- CAS Key Laboratory of Special Pathogens and Biosafety, Center for Emerging Infectious Diseases, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, 430071, China
| | - Qiong Wu
- Key Laboratory of Magnetic Resonance in Biological Systems, State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, National Center for Magnetic Resonance in Wuhan, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan, 430071, China
| | - Dan Wang
- Key Laboratory of Magnetic Resonance in Biological Systems, State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, National Center for Magnetic Resonance in Wuhan, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan, 430071, China.,University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Conggang Li
- Key Laboratory of Magnetic Resonance in Biological Systems, State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, National Center for Magnetic Resonance in Wuhan, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan, 430071, China
| | - Maili Liu
- Key Laboratory of Magnetic Resonance in Biological Systems, State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, National Center for Magnetic Resonance in Wuhan, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan, 430071, China
| | - Pei Zhou
- Department of Biochemistry, Duke University Medical Center, Durham, NC, 27710, USA
| | - Ling Jiang
- Key Laboratory of Magnetic Resonance in Biological Systems, State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, National Center for Magnetic Resonance in Wuhan, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan, 430071, China.
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46
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Straube R. Analysis of network motifs in cellular regulation: Structural similarities, input-output relations and signal integration. Biosystems 2017; 162:215-232. [PMID: 29107640 DOI: 10.1016/j.biosystems.2017.10.012] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2017] [Revised: 10/22/2017] [Accepted: 10/23/2017] [Indexed: 02/07/2023]
Abstract
Much of the complexity of regulatory networks derives from the necessity to integrate multiple signals and to avoid malfunction due to cross-talk or harmful perturbations. Hence, one may expect that the input-output behavior of larger networks is not necessarily more complex than that of smaller network motifs which suggests that both can, under certain conditions, be described by similar equations. In this review, we illustrate this approach by discussing the similarities that exist in the steady state descriptions of a simple bimolecular reaction, covalent modification cycles and bacterial two-component systems. Interestingly, in all three systems fundamental input-output characteristics such as thresholds, ultrasensitivity or concentration robustness are described by structurally similar equations. Depending on the system the meaning of the parameters can differ ranging from protein concentrations and affinity constants to complex parameter combinations which allows for a quantitative understanding of signal integration in these systems. We argue that this approach may also be extended to larger regulatory networks.
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Affiliation(s)
- Ronny Straube
- Max Planck Institute for Dynamics of Complex Technical Systems Magdeburg, Sandtorstr. 1, D-39106 Magdeburg, Germany
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47
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Vo CD, Shebert HL, Zikovich S, Dryer RA, Huang TP, Moran LJ, Cho J, Wassarman DR, Falahee BE, Young PD, Gu GH, Heinl JF, Hammond JW, Jackvony TN, Frederick TE, Blair JA. Repurposing Hsp90 inhibitors as antibiotics targeting histidine kinases. Bioorg Med Chem Lett 2017; 27:5235-5244. [PMID: 29110989 DOI: 10.1016/j.bmcl.2017.10.036] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2017] [Revised: 10/05/2017] [Accepted: 10/18/2017] [Indexed: 01/15/2023]
Abstract
To address the growing need for new antimicrobial agents, we explored whether inhibition of bacterial signaling machinery could inhibit bacterial growth. Because bacteria rely on two-component signaling systems to respond to environmental changes, and because these systems are both highly conserved and mediated by histidine kinases, inhibiting histidine kinases may provide broad spectrum antimicrobial activity. The histidine kinase ATP binding domain is conserved with the ATPase domain of eukaryotic Hsp90 molecular chaperones. To find a chemical scaffold for compounds that target histidine kinases, we leveraged this conservation. We screened ATP competitive Hsp90 inhibitors against CckA, an essential histidine kinase in Caulobacter crescentus that controls cell growth, and showed that the diaryl pyrazole is a promising scaffold for histidine kinase inhibition. We synthesized a panel of derivatives and found that they inhibit the histidine kinases C. crescentus CckA and Salmonella PhoQ but not C. crescentus DivJ; and they inhibit bacterial growth in both Gram-negative and Gram-positive bacterial strains.
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Affiliation(s)
- Chau D Vo
- Williams College, Department of Chemistry, 47 Lab Campus Drive, Williamstown, MA 01267, USA
| | - Hanna L Shebert
- Williams College, Department of Chemistry, 47 Lab Campus Drive, Williamstown, MA 01267, USA
| | - Shannon Zikovich
- Williams College, Department of Chemistry, 47 Lab Campus Drive, Williamstown, MA 01267, USA
| | - Rebecca A Dryer
- Williams College, Department of Chemistry, 47 Lab Campus Drive, Williamstown, MA 01267, USA
| | - Tony P Huang
- Williams College, Department of Chemistry, 47 Lab Campus Drive, Williamstown, MA 01267, USA
| | - Lindsey J Moran
- Williams College, Department of Chemistry, 47 Lab Campus Drive, Williamstown, MA 01267, USA
| | - Juno Cho
- Williams College, Department of Chemistry, 47 Lab Campus Drive, Williamstown, MA 01267, USA
| | - Douglas R Wassarman
- Williams College, Department of Chemistry, 47 Lab Campus Drive, Williamstown, MA 01267, USA
| | - Bryn E Falahee
- Williams College, Department of Chemistry, 47 Lab Campus Drive, Williamstown, MA 01267, USA
| | - Peter D Young
- Williams College, Department of Chemistry, 47 Lab Campus Drive, Williamstown, MA 01267, USA
| | - Garrick H Gu
- Williams College, Department of Chemistry, 47 Lab Campus Drive, Williamstown, MA 01267, USA
| | - James F Heinl
- Williams College, Department of Chemistry, 47 Lab Campus Drive, Williamstown, MA 01267, USA
| | - John W Hammond
- Williams College, Department of Chemistry, 47 Lab Campus Drive, Williamstown, MA 01267, USA
| | - Taylor N Jackvony
- Williams College, Department of Chemistry, 47 Lab Campus Drive, Williamstown, MA 01267, USA
| | - Thomas E Frederick
- Department of Biochemistry & Molecular Biophysics, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Jimmy A Blair
- Williams College, Department of Chemistry, 47 Lab Campus Drive, Williamstown, MA 01267, USA.
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48
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Dapkūnas J, Olechnovič K, Venclovas Č. Modeling of protein complexes in CAPRI Round 37 using template-based approach combined with model selection. Proteins 2017; 86 Suppl 1:292-301. [DOI: 10.1002/prot.25378] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2017] [Revised: 08/25/2017] [Accepted: 09/10/2017] [Indexed: 01/14/2023]
Affiliation(s)
- Justas Dapkūnas
- Institute of Biotechnology, Vilnius University, Saulėtekio 7; Vilnius LT-10257 Lithuania
| | - Kliment Olechnovič
- Institute of Biotechnology, Vilnius University, Saulėtekio 7; Vilnius LT-10257 Lithuania
| | - Česlovas Venclovas
- Institute of Biotechnology, Vilnius University, Saulėtekio 7; Vilnius LT-10257 Lithuania
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49
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Mechaly AE, Soto Diaz S, Sassoon N, Buschiazzo A, Betton JM, Alzari PM. Structural Coupling between Autokinase and Phosphotransferase Reactions in a Bacterial Histidine Kinase. Structure 2017; 25:939-944.e3. [PMID: 28552574 DOI: 10.1016/j.str.2017.04.011] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2016] [Revised: 03/06/2017] [Accepted: 04/28/2017] [Indexed: 01/22/2023]
Abstract
Bacterial two-component systems consist of a sensor histidine kinase (HK) and a response regulator (RR). HKs are homodimers that catalyze the autophosphorylation of a histidine residue and the subsequent phosphoryl transfer to its RR partner, triggering an adaptive response. How the HK autokinase and phosphotransferase activities are coordinated remains unclear. Here, we report X-ray structures of the prototypical HK CpxA trapped as a hemi-phosphorylated dimer, and of the receiver domain from the RR partner, CpxR. Our results reveal that the two catalytic reactions can occur simultaneously, one in each protomer of the asymmetric CpxA dimer. Furthermore, the increase of autokinase activity in the presence of phosphotransfer-impaired CpxR put forward the idea of an allosteric switching mechanism, according to which CpxR binding to one CpxA protomer triggers autophosphorylation in the second protomer. The ensuing dynamical model provides a mechanistic explanation of how HKs can efficiently orchestrate two catalytic reactions involving large-scale protein motions.
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Affiliation(s)
- Ariel E Mechaly
- Institut Pasteur, Unité de Microbiologie Structurale, CNRS UMR 3528 & Université Paris Diderot, Sorbonne Paris Cité, 25 rue du Dr. Roux, 75724, Paris Cedex 15, France.
| | - Silvia Soto Diaz
- Institut Pasteur, Unité de Microbiologie Structurale, CNRS UMR 3528 & Université Paris Diderot, Sorbonne Paris Cité, 25 rue du Dr. Roux, 75724, Paris Cedex 15, France
| | - Nathalie Sassoon
- Institut Pasteur, Unité de Microbiologie Structurale, CNRS UMR 3528 & Université Paris Diderot, Sorbonne Paris Cité, 25 rue du Dr. Roux, 75724, Paris Cedex 15, France
| | - Alejandro Buschiazzo
- Institut Pasteur de Montevideo, Laboratory of Molecular and Structural Microbiology, Montevideo 11400, Uruguay
| | - Jean-Michel Betton
- Institut Pasteur, Unité de Microbiologie Structurale, CNRS UMR 3528 & Université Paris Diderot, Sorbonne Paris Cité, 25 rue du Dr. Roux, 75724, Paris Cedex 15, France
| | - Pedro M Alzari
- Institut Pasteur, Unité de Microbiologie Structurale, CNRS UMR 3528 & Université Paris Diderot, Sorbonne Paris Cité, 25 rue du Dr. Roux, 75724, Paris Cedex 15, France.
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Abstract
Cyclic dinucleotides (CDNs) are highly versatile signalling molecules that control various important biological processes in bacteria. The best-studied example is cyclic di-GMP (c-di-GMP). Known since the late 1980s, it is now recognized as a near-ubiquitous second messenger that coordinates diverse aspects of bacterial growth and behaviour, including motility, virulence, biofilm formation and cell cycle progression. In this Review, we discuss important new insights that have been gained into the molecular principles of c-di-GMP synthesis and degradation, which are mediated by diguanylate cyclases and c-di-GMP-specific phosphodiesterases, respectively, and the cellular functions that are exerted by c-di-GMP-binding effectors and their diverse targets. Finally, we provide a short overview of the signalling versatility of other CDNs, including c-di-AMP and cGMP-AMP (cGAMP).
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