1
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Zhang K, Qin M, Hou Y, Zhang W, Wang Z, Wang H. Efficient production of guanosine in Escherichia coli by combinatorial metabolic engineering. Microb Cell Fact 2024; 23:182. [PMID: 38898430 PMCID: PMC11186194 DOI: 10.1186/s12934-024-02452-8] [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: 04/22/2024] [Accepted: 06/06/2024] [Indexed: 06/21/2024] Open
Abstract
BACKGROUND Guanosine is a purine nucleoside that is widely used as a raw material for food additives and pharmaceutical products. Microbial fermentation is the main production method of guanosine. However, the guanosine-producing strains possess multiple metabolic pathway interactions and complex regulatory mechanisms. The lack of strains with efficiently producing-guanosine greatly limited industrial application. RESULTS We attempted to efficiently produce guanosine in Escherichia coli using systematic metabolic engineering. First, we overexpressed the purine synthesis pathway from Bacillus subtilis and the prs gene, and deleted three genes involved in guanosine catabolism to increase guanosine accumulation. Subsequently, we attenuated purA expression and eliminated feedback and transcription dual inhibition. Then, we modified the metabolic flux of the glycolysis and Entner-Doudoroff (ED) pathways and performed redox cofactors rebalancing. Finally, transporter engineering and enhancing the guanosine synthesis pathway further increased the guanosine titre to 134.9 mg/L. After 72 h of the fed-batch fermentation in shake-flask, the guanosine titre achieved 289.8 mg/L. CONCLUSIONS Our results reveal that the guanosine synthesis pathway was successfully optimized by combinatorial metabolic engineering, which could be applicable to the efficient synthesis of other nucleoside products.
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Affiliation(s)
- Kun Zhang
- Henan Province Engineering Laboratory for Bioconversion Technology of Functional Microbes, College of Life Sciences, Henan Normal University, Xinxiang, 453007, China
| | - Mengxing Qin
- Henan Province Engineering Laboratory for Bioconversion Technology of Functional Microbes, College of Life Sciences, Henan Normal University, Xinxiang, 453007, China
| | - Yu Hou
- Henan Province Engineering Laboratory for Bioconversion Technology of Functional Microbes, College of Life Sciences, Henan Normal University, Xinxiang, 453007, China
| | - Wenwen Zhang
- Henan Province Engineering Laboratory for Bioconversion Technology of Functional Microbes, College of Life Sciences, Henan Normal University, Xinxiang, 453007, China
| | - Zhenyu Wang
- Henan Province Engineering Laboratory for Bioconversion Technology of Functional Microbes, College of Life Sciences, Henan Normal University, Xinxiang, 453007, China
| | - Hailei Wang
- Henan Province Engineering Laboratory for Bioconversion Technology of Functional Microbes, College of Life Sciences, Henan Normal University, Xinxiang, 453007, China.
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2
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Bivona D, Bonomo C, Colombini L, Bonacci PG, Privitera GF, Caruso G, Caraci F, Santoro F, Musso N, Bongiorno D, Iannelli F, Stefani S. Generation and Characterization of Stable Small Colony Variants of USA300 Staphylococcus aureus in RAW 264.7 Murine Macrophages. Antibiotics (Basel) 2024; 13:264. [PMID: 38534699 DOI: 10.3390/antibiotics13030264] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2024] [Revised: 03/08/2024] [Accepted: 03/13/2024] [Indexed: 03/28/2024] Open
Abstract
Intracellular survival and immune evasion are typical features of staphylococcal infections. USA300 is a major clone of methicillin-resistant S. aureus (MRSA), a community- and hospital-acquired pathogen capable of disseminating throughout the body and evading the immune system. Carnosine is an endogenous dipeptide characterized by antioxidant and anti-inflammatory properties acting on the peripheral (macrophages) and tissue-resident (microglia) immune system. In this work, RAW 264.7 murine macrophages were infected with the USA300 ATCC BAA-1556 S. aureus strain and treated with 20 mM carnosine and/or 32 mg/L erythromycin. Stable small colony variant (SCV) formation on blood agar medium was obtained after 48 h of combined treatment. Whole genome sequencing of the BAA-1556 strain and its stable derivative SCVs when combining Illumina and nanopore technologies revealed three single nucleotide differences, including a nonsense mutation in the shikimate kinase gene aroK. Gene expression analysis showed a significant up-regulation of the uhpt and sdrE genes in the stable SCVs compared with the wild-type, likely involved in adaptation to the intracellular milieu.
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Affiliation(s)
- Dalida Bivona
- Medical Molecular Microbiology and Antibiotic Resistance Laboratory (MMARLab), Department of Biomedical and Biotechnological Sciences (BIOMETEC), University of Catania, 95123 Catania, Italy
| | - Carmelo Bonomo
- Medical Molecular Microbiology and Antibiotic Resistance Laboratory (MMARLab), Department of Biomedical and Biotechnological Sciences (BIOMETEC), University of Catania, 95123 Catania, Italy
| | - Lorenzo Colombini
- Laboratory of Molecular Microbiology and Biotechnology, Department of Medical Biotechnologies, University of Siena, 53100 Siena, Italy
| | - Paolo G Bonacci
- Medical Molecular Microbiology and Antibiotic Resistance Laboratory (MMARLab), Department of Biomedical and Biotechnological Sciences (BIOMETEC), University of Catania, 95123 Catania, Italy
| | - Grete F Privitera
- Department of Clinical and Experimental Medicine, University of Catania, 95123 Catania, Italy
| | - Giuseppe Caruso
- Department of Drug and Health Sciences, University of Catania, 95125 Catania, Italy
- Oasi Research Institute-IRCCS, 94018 Troina, Italy
| | - Filippo Caraci
- Department of Drug and Health Sciences, University of Catania, 95125 Catania, Italy
- Oasi Research Institute-IRCCS, 94018 Troina, Italy
| | - Francesco Santoro
- Laboratory of Molecular Microbiology and Biotechnology, Department of Medical Biotechnologies, University of Siena, 53100 Siena, Italy
| | - Nicolò Musso
- Biochemical Section, Department of Biomedical and Biotechnological Sciences (BIOMETEC), University of Catania, 95123 Catania, Italy
| | - Dafne Bongiorno
- Medical Molecular Microbiology and Antibiotic Resistance Laboratory (MMARLab), Department of Biomedical and Biotechnological Sciences (BIOMETEC), University of Catania, 95123 Catania, Italy
| | - Francesco Iannelli
- Laboratory of Molecular Microbiology and Biotechnology, Department of Medical Biotechnologies, University of Siena, 53100 Siena, Italy
| | - Stefania Stefani
- Medical Molecular Microbiology and Antibiotic Resistance Laboratory (MMARLab), Department of Biomedical and Biotechnological Sciences (BIOMETEC), University of Catania, 95123 Catania, Italy
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3
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Ayoub N, Gedeon A, Munier-Lehmann H. A journey into the regulatory secrets of the de novo purine nucleotide biosynthesis. Front Pharmacol 2024; 15:1329011. [PMID: 38444943 PMCID: PMC10912719 DOI: 10.3389/fphar.2024.1329011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2023] [Accepted: 02/01/2024] [Indexed: 03/07/2024] Open
Abstract
De novo purine nucleotide biosynthesis (DNPNB) consists of sequential reactions that are majorly conserved in living organisms. Several regulation events take place to maintain physiological concentrations of adenylate and guanylate nucleotides in cells and to fine-tune the production of purine nucleotides in response to changing cellular demands. Recent years have seen a renewed interest in the DNPNB enzymes, with some being highlighted as promising targets for therapeutic molecules. Herein, a review of two newly revealed modes of regulation of the DNPNB pathway has been carried out: i) the unprecedent allosteric regulation of one of the limiting enzymes of the pathway named inosine 5'-monophosphate dehydrogenase (IMPDH), and ii) the supramolecular assembly of DNPNB enzymes. Moreover, recent advances that revealed the therapeutic potential of DNPNB enzymes in bacteria could open the road for the pharmacological development of novel antibiotics.
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Affiliation(s)
- Nour Ayoub
- Institut Pasteur, Université Paris Cité, INSERM UMRS-1124, Paris, France
| | - Antoine Gedeon
- Sorbonne Université, École Normale Supérieure, Université PSL, CNRS UMR7203, Laboratoire des Biomolécules, LBM, Paris, France
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4
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Maisat W, Yuki K. Volatile anesthetic isoflurane exposure facilitates Enterococcus biofilm infection. FASEB J 2023; 37:e23186. [PMID: 37665578 PMCID: PMC10495085 DOI: 10.1096/fj.202301128r] [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: 06/06/2023] [Revised: 08/21/2023] [Accepted: 08/24/2023] [Indexed: 09/05/2023]
Abstract
Enterococcus faecalis (E. faecalis) is one of the major pathogenic bacteria responsible for surgical site infections. Biofilm infections are major hospital-acquired infections. Previous studies suggested that ions could regulate biofilm formation in microbes. Volatile anesthetics, frequently administered in surgical setting, target ion channels. Here, we investigated the role of ion channels/transporters and volatile anesthetics in the biofilm formation by E. faecalis MMH594 strain and its ion transporter mutants. We found that a chloride transporter mutant significantly reduced biofilm formation compared to the parental strain. Downregulation of teichoic acid biosynthesis in the chloride transporter mutant impaired biofilm matrix formation and cellular adhesion, leading to mitigated biofilm formation. Among anesthetics, isoflurane exposure enhanced biofilm formation in vitro and in vivo. The upregulation of de novo purine biosynthesis pathway by isoflurane exposure potentially enhanced biofilm formation, an essential process for DNA, RNA, and ATP synthesis. We also demonstrated that isoflurane exposure to E. faecalis increased cyclic-di-AMP and extracellular DNA production, consistent with the increased purine biosynthesis. We further showed that isoflurane enhanced the enzymatic activity of phosphoribosyl pyrophosphate synthetase (PRPP-S). With the hypothesis that isoflurane directly bound to PRPP-S, we predicted isoflurane binding site on it using rigid docking. Our study provides a better understanding of the underlying mechanisms of E. faecalis biofilm formation and highlights the potential impact of an ion transporter and volatile anesthetic on this process. These findings may lead to the development of novel strategies for preventing E. faecalis biofilm formation and improving patient outcomes in clinical settings.
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Affiliation(s)
- Wiriya Maisat
- Department of Anesthesiology, Critical Care and Pain Medicine, Cardiac Anesthesia Division, Boston Children’s Hospital, Boston, MA, USA
- Department of Anaesthesia, Harvard Medical School, Boston, MA, USA
- Department of Immunology, Harvard Medical School, Boston, MA, USA
- Broad Institute of Harvard and MIT, Cambridge, MA, USA
- Department of Anesthesiology, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand
| | - Koichi Yuki
- Department of Anesthesiology, Critical Care and Pain Medicine, Cardiac Anesthesia Division, Boston Children’s Hospital, Boston, MA, USA
- Department of Anaesthesia, Harvard Medical School, Boston, MA, USA
- Department of Immunology, Harvard Medical School, Boston, MA, USA
- Broad Institute of Harvard and MIT, Cambridge, MA, USA
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5
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Kavita K, Breaker RR. Discovering riboswitches: the past and the future. Trends Biochem Sci 2023; 48:119-141. [PMID: 36150954 PMCID: PMC10043782 DOI: 10.1016/j.tibs.2022.08.009] [Citation(s) in RCA: 51] [Impact Index Per Article: 51.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2022] [Revised: 08/18/2022] [Accepted: 08/26/2022] [Indexed: 01/25/2023]
Abstract
Riboswitches are structured noncoding RNA domains used by many bacteria to monitor the concentrations of target ligands and regulate gene expression accordingly. In the past 20 years over 55 distinct classes of natural riboswitches have been discovered that selectively sense small molecules or elemental ions, and thousands more are predicted to exist. Evidence suggests that some riboswitches might be direct descendants of the RNA-based sensors and switches that were likely present in ancient organisms before the evolutionary emergence of proteins. We provide an overview of the current state of riboswitch research, focusing primarily on the discovery of riboswitches, and speculate on the major challenges facing researchers in the field.
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Affiliation(s)
- Kumari Kavita
- Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, CT 06520-8103, USA
| | - Ronald R Breaker
- Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, CT 06520-8103, USA; Howard Hughes Medical Institute, Yale University, New Haven, CT 06520-8103, USA; Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06520-8103, USA.
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6
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Liu Y, Zhang Q, Qi X, Gao H, Wang M, Guan H, Yu B. Metabolic Engineering of Bacillus subtilis for Riboflavin Production: A Review. Microorganisms 2023; 11:microorganisms11010164. [PMID: 36677456 PMCID: PMC9863419 DOI: 10.3390/microorganisms11010164] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2022] [Revised: 12/30/2022] [Accepted: 01/02/2023] [Indexed: 01/11/2023] Open
Abstract
Riboflavin (vitamin B2) is one of the essential vitamins that the human body needs to maintain normal metabolism. Its biosynthesis has become one of the successful models for gradual replacement of traditional chemical production routes. B. subtilis is characterized by its short fermentation time and high yield, which shows a huge competitive advantage in microbial fermentation for production of riboflavin. This review summarized the advancements of regulation on riboflavin production as well as the synthesis of two precursors of ribulose-5-phosphate riboflavin (Ru5P) and guanosine 5'-triphosphate (GTP) in B. subtilis. The different strategies to improve production of riboflavin by metabolic engineering were also reviewed.
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Affiliation(s)
- Yang Liu
- Key Laboratory of Biofuels and Biochemical Engineering, SINOPEC (Dalian) Research Institute of Petroleum and Petro-Chemicals Co., Ltd., Dalian 116045, China
- CAS Key Laboratory of Microbial Physiological and Metabolic Engineering, State Key Laboratory of Mycology, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China
| | - Quan Zhang
- Key Laboratory of Biofuels and Biochemical Engineering, SINOPEC (Dalian) Research Institute of Petroleum and Petro-Chemicals Co., Ltd., Dalian 116045, China
- Correspondence: (Q.Z.); (B.Y.)
| | - Xiaoxiao Qi
- CAS Key Laboratory of Microbial Physiological and Metabolic Engineering, State Key Laboratory of Mycology, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China
- School of Life Science, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Huipeng Gao
- Key Laboratory of Biofuels and Biochemical Engineering, SINOPEC (Dalian) Research Institute of Petroleum and Petro-Chemicals Co., Ltd., Dalian 116045, China
| | - Meng Wang
- Key Laboratory of Biofuels and Biochemical Engineering, SINOPEC (Dalian) Research Institute of Petroleum and Petro-Chemicals Co., Ltd., Dalian 116045, China
| | - Hao Guan
- Key Laboratory of Biofuels and Biochemical Engineering, SINOPEC (Dalian) Research Institute of Petroleum and Petro-Chemicals Co., Ltd., Dalian 116045, China
| | - Bo Yu
- CAS Key Laboratory of Microbial Physiological and Metabolic Engineering, State Key Laboratory of Mycology, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China
- Correspondence: (Q.Z.); (B.Y.)
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7
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Smith-Peter E, Séguin DL, St-Pierre É, Sekulovic O, Jeanneau S, Tremblay-Tétreault C, Lamontagne AM, Jacques PÉ, Lafontaine DA, Fortier LC. Inactivation of the riboswitch-controlled GMP synthase GuaA in Clostridioides difficile is associated with severe growth defects and poor infectivity in a mouse model of infection. RNA Biol 2021; 18:699-710. [PMID: 34612173 DOI: 10.1080/15476286.2021.1978768] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022] Open
Abstract
Clostridioides difficile is the main cause of nosocomial antibiotic-associated diarrhoea. There is a need for new antimicrobials to tackle this pathogen. Guanine riboswitches have been proposed as promising new antimicrobial targets, but experimental evidence of their importance in C. difficile is missing. The genome of C. difficile encodes four distinct guanine riboswitches, each controlling a single gene involved in purine metabolism and transport. One of them controls the expression of guaA, encoding a guanosine monophosphate (GMP) synthase. Here, using in-line probing and GusA reporter assays, we show that these riboswitches are functional in C. difficile and cause premature transcription termination upon binding of guanine. All riboswitches exhibit a high affinity for guanine characterized by Kd values in the low nanomolar range. Xanthine and guanosine also bind the guanine riboswitches, although with less affinity. Inactivating the GMP synthase (guaA) in C. difficile strain 630 led to cell death in minimal growth conditions, but not in rich medium. Importantly, the capacity of a guaA mutant to colonize the mouse gut was significantly reduced. Together, these results demonstrate the importance of de novo GMP biosynthesis in C. difficile during infection, suggesting that targeting guanine riboswitches with analogues could be a viable therapeutic strategy.
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Affiliation(s)
- Erich Smith-Peter
- Department of Microbiology and Infectious Diseases, Faculty of Medicine and Health Sciences, Université De Sherbrooke, Sherbrooke, Quebec, Canada.,Department of Biology, Faculty of Science, Université De Sherbrooke, Sherbrooke, Quebec, Canada
| | - David Lalonde Séguin
- Department of Microbiology and Infectious Diseases, Faculty of Medicine and Health Sciences, Université De Sherbrooke, Sherbrooke, Quebec, Canada
| | - Émilie St-Pierre
- Department of Microbiology and Infectious Diseases, Faculty of Medicine and Health Sciences, Université De Sherbrooke, Sherbrooke, Quebec, Canada
| | - Ognjen Sekulovic
- Department of Microbiology and Infectious Diseases, Faculty of Medicine and Health Sciences, Université De Sherbrooke, Sherbrooke, Quebec, Canada
| | - Simon Jeanneau
- Department of Biology, Faculty of Science, Université De Sherbrooke, Sherbrooke, Quebec, Canada
| | | | - Anne-Marie Lamontagne
- Department of Biology, Faculty of Science, Université De Sherbrooke, Sherbrooke, Quebec, Canada
| | - Pierre-Étienne Jacques
- Department of Biology, Faculty of Science, Université De Sherbrooke, Sherbrooke, Quebec, Canada
| | - Daniel A Lafontaine
- Department of Biology, Faculty of Science, Université De Sherbrooke, Sherbrooke, Quebec, Canada
| | - Louis-Charles Fortier
- Department of Microbiology and Infectious Diseases, Faculty of Medicine and Health Sciences, Université De Sherbrooke, Sherbrooke, Quebec, Canada
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8
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Mfd regulates RNA polymerase association with hard-to-transcribe regions in vivo, especially those with structured RNAs. Proc Natl Acad Sci U S A 2021; 118:2008498118. [PMID: 33443179 DOI: 10.1073/pnas.2008498118] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
RNA polymerase (RNAP) encounters various roadblocks during transcription. These obstacles can impede RNAP movement and influence transcription, ultimately necessitating the activity of RNAP-associated factors. One such factor is the bacterial protein Mfd, a highly conserved DNA translocase and evolvability factor that interacts with RNAP. Although Mfd is thought to function primarily in the repair of DNA lesions that stall RNAP, increasing evidence suggests that it may also be important for transcription regulation. However, this is yet to be fully characterized. To shed light on Mfd's in vivo functions, we identified the chromosomal regions where it associates. We analyzed Mfd's impact on RNAP association and transcription regulation genome-wide. We found that Mfd represses RNAP association at many chromosomal regions. We found that these regions show increased RNAP pausing, suggesting that they are hard to transcribe. Interestingly, we noticed that the majority of the regions where Mfd regulates transcription contain highly structured regulatory RNAs. The RNAs identified regulate a myriad of biological processes, ranging from metabolism to transfer RNA regulation to toxin-antitoxin (TA) functions. We found that cells lacking Mfd are highly sensitive to toxin overexpression. Finally, we found that Mfd promotes mutagenesis in at least one toxin gene, suggesting that its function in regulating transcription may promote evolution of certain TA systems and other regions containing strong RNA secondary structures. We conclude that Mfd is an RNAP cofactor that is important, and at times critical, for transcription regulation at hard-to-transcribe regions, especially those that express structured regulatory RNAs.
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9
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Sherlock ME, Breaker RR. Former orphan riboswitches reveal unexplored areas of bacterial metabolism, signaling, and gene control processes. RNA (NEW YORK, N.Y.) 2020; 26:675-693. [PMID: 32165489 PMCID: PMC7266159 DOI: 10.1261/rna.074997.120] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Comparative sequence analyses have been used to discover numerous classes of structured noncoding RNAs, some of which are riboswitches that specifically recognize small-molecule or elemental ion ligands and influence expression of adjacent downstream genes. Determining the correct identity of the ligand for a riboswitch candidate typically is aided by an understanding of the genes under its regulatory control. Riboswitches whose ligands were straightforward to identify have largely been associated with well-characterized metabolic pathways, such as coenzyme or amino acid biosynthesis. Riboswitch candidates whose ligands resist identification, collectively known as orphan riboswitches, are often associated with genes coding for proteins of unknown function, or genes for various proteins with no established link to one another. The cognate ligands for 16 former orphan riboswitch motifs have been identified to date. The successful pursuit of the ligands for these classes has provided insight into areas of biology that are not yet fully explored, such as ion homeostasis, signaling networks, and other previously underappreciated biochemical or physiological processes. Herein we discuss the strategies and methods used to match ligands with orphan riboswitch classes, and overview the lessons learned to inform and motivate ongoing efforts to identify ligands for the many remaining candidates.
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Affiliation(s)
- Madeline E Sherlock
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut 06520, USA
| | - Ronald R Breaker
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut 06520, USA
- Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, Connecticut 06520, USA
- Howard Hughes Medical Institute, Yale University, New Haven, Connecticut 06520, USA
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10
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Papp K, Mau RL, Hayer M, Koch BJ, Hungate BA, Schwartz E. Quantitative stable isotope probing with H 218O reveals that most bacterial taxa in soil synthesize new ribosomal RNA. THE ISME JOURNAL 2018; 12:3043-3045. [PMID: 30042501 PMCID: PMC6246559 DOI: 10.1038/s41396-018-0233-7] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/27/2017] [Revised: 03/16/2018] [Accepted: 03/19/2018] [Indexed: 11/09/2022]
Abstract
Most soil bacterial taxa are thought to be dormant, or inactive, yet the extent to which they synthetize new rRNA is poorly understood. We analyzed 18O composition of RNA extracted from soil incubated with H218O and used quantitative stable isotope probing to characterize rRNA synthesis among microbial taxa. RNA was not fully labeled with 18O, peaking at a mean of 23.6 ± 6.8 atom percent excess (APE) 18O after eight days of incubation, suggesting some ribonucleotides in soil were more than eight days old. Microbial taxa varied in the degree they incorporated 18O into their rRNA over time and there was no correlation between the APE 18O of bacterial rRNA and their rRNA to DNA ratios, suggesting that the ratios were not appropriate to measure ribonucleotide synthesis. Our study indicates that, on average, 94% of soil taxa produced new rRNA and therefore were metabolically active.
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Affiliation(s)
- Katerina Papp
- Center for Ecosystem Science and Society, Northern Arizona University, Flagstaff, AZ, USA.
- Department of Biological Sciences, Northern Arizona University, Flagstaff, AZ, USA.
- Division of Hydrological Sciences, Desert Research Institute, Las Vegas, NV, USA.
- Department of Civil and Environmental Engineering and Construction, University of Las Vegas, Las Vegas, NV, USA.
| | - Rebecca L Mau
- Center for Ecosystem Science and Society, Northern Arizona University, Flagstaff, AZ, USA
- Department of Biological Sciences, Northern Arizona University, Flagstaff, AZ, USA
| | - Michaela Hayer
- Center for Ecosystem Science and Society, Northern Arizona University, Flagstaff, AZ, USA
- Department of Biological Sciences, Northern Arizona University, Flagstaff, AZ, USA
| | - Benjamin J Koch
- Center for Ecosystem Science and Society, Northern Arizona University, Flagstaff, AZ, USA
- Department of Biological Sciences, Northern Arizona University, Flagstaff, AZ, USA
| | - Bruce A Hungate
- Center for Ecosystem Science and Society, Northern Arizona University, Flagstaff, AZ, USA
- Department of Biological Sciences, Northern Arizona University, Flagstaff, AZ, USA
| | - Egbert Schwartz
- Center for Ecosystem Science and Society, Northern Arizona University, Flagstaff, AZ, USA
- Department of Biological Sciences, Northern Arizona University, Flagstaff, AZ, USA
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11
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Papp K, Hungate BA, Schwartz E. Microbial rRNA Synthesis and Growth Compared through Quantitative Stable Isotope Probing with H 218O. Appl Environ Microbiol 2018; 84:e02441-17. [PMID: 29439990 PMCID: PMC5881069 DOI: 10.1128/aem.02441-17] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2017] [Accepted: 02/07/2018] [Indexed: 02/01/2023] Open
Abstract
Growing bacteria have a high concentration of ribosomes to ensure sufficient protein synthesis, which is necessary for genome replication and cellular division. To elucidate whether metabolic activity of soil microorganisms is coupled with growth, we investigated the relationship between rRNA and DNA synthesis in a soil bacterial community using quantitative stable isotope probing (qSIP) with H218O. Most soil bacterial taxa were metabolically active and grew, and there was no significant difference between the isotopic composition of DNA and RNA extracted from soil incubated with H218O. The positive correlation between 18O content of DNA and rRNA of taxa, with a slope statistically indistinguishable from 1 (slope = 0.96; 95% confidence interval [CI], 0.90 to 1.02), indicated that few taxa made new rRNA without synthesizing new DNA. There was no correlation between rRNA-to-DNA ratios obtained from sequencing libraries and the atom percent excess (APE) 18O values of DNA or rRNA, suggesting that the ratio of rRNA to DNA is a poor indicator of microbial growth or rRNA synthesis. Our results support the notion that metabolic activity is strongly coupled to cellular division and suggest that nondividing taxa do not dominate soil metabolic activity.IMPORTANCE Using quantitative stable isotope probing of microbial RNA and DNA with H218O, we show that most soil taxa are metabolically active and grow because their nucleic acids are significantly labeled with 18O. A majority of the populations that make new rRNA also grow, which argues against the common paradigm that most soil taxa are dormant. Additionally, our results indicate that relative sequence abundance-based RNA-to-DNA ratios, which are frequently used for identifying active microbial populations in the environment, underestimate the number of metabolically active taxa within soil microbial communities.
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Affiliation(s)
- Katerina Papp
- Center for Ecosystem Science and Society, Northern Arizona University, Flagstaff, Arizona, USA
- Department of Biological Sciences, Northern Arizona University, Flagstaff, Arizona, USA
| | - Bruce A Hungate
- Center for Ecosystem Science and Society, Northern Arizona University, Flagstaff, Arizona, USA
- Department of Biological Sciences, Northern Arizona University, Flagstaff, Arizona, USA
| | - Egbert Schwartz
- Center for Ecosystem Science and Society, Northern Arizona University, Flagstaff, Arizona, USA
- Department of Biological Sciences, Northern Arizona University, Flagstaff, Arizona, USA
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12
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Knappenberger AJ, Reiss CW, Strobel SA. Structures of two aptamers with differing ligand specificity reveal ruggedness in the functional landscape of RNA. eLife 2018; 7:36381. [PMID: 29877798 PMCID: PMC6031431 DOI: 10.7554/elife.36381] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2018] [Accepted: 06/05/2018] [Indexed: 01/07/2023] Open
Abstract
Two classes of riboswitches related to the ykkC guanidine-I riboswitch bind phosphoribosyl pyrophosphate (PRPP) and guanosine tetraphosphate (ppGpp). Here we report the co-crystal structure of the PRPP aptamer and its ligand. We also report the structure of the G96A point mutant that prefers ppGpp over PRPP with a dramatic 40,000-fold switch in specificity. The ends of the aptamer form a helix that is not present in the guanidine aptamer and is involved in the expression platform. In the mutant, the base of ppGpp replaces G96 in three-dimensional space. This disrupts the S-turn, which is a primary structural feature of the ykkC RNA motif. These dramatic differences in ligand specificity are achieved with minimal mutations. ykkC aptamers are therefore a prime example of an RNA fold with a rugged fitness landscape. The ease with which the ykkC aptamer acquires new specificity represents a striking case of evolvability in RNA.
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Affiliation(s)
- Andrew John Knappenberger
- Department of Molecular Biophysics and BiochemistryYale UniversityNew HavenUnited States,Chemical Biology InstituteYale UniversityWest HavenUnited States
| | - Caroline Wetherington Reiss
- Department of Molecular Biophysics and BiochemistryYale UniversityNew HavenUnited States,Chemical Biology InstituteYale UniversityWest HavenUnited States
| | - Scott A Strobel
- Department of Molecular Biophysics and BiochemistryYale UniversityNew HavenUnited States,Chemical Biology InstituteYale UniversityWest HavenUnited States
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Zhang W, Guo H, Cao C, Li L, Kwok LY, Zhang H, Sun Z. Adaptation of Lactobacillus casei Zhang to Gentamycin Involves an Alkaline Shock Protein. Front Microbiol 2017; 8:2316. [PMID: 29218040 PMCID: PMC5703869 DOI: 10.3389/fmicb.2017.02316] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2017] [Accepted: 11/09/2017] [Indexed: 12/26/2022] Open
Abstract
Lactobacillus (L. casei) Zhang is a koumiss-originated probiotic strain, which was used as a model in a long-term antibiotics-driven evolution experiment to reveal bacterial evolutionary dynamics; and we isolated gentamycin-resistant L. casei Zhang descendents. To decipher the gentamycin resistance mechanism, here we cultivated the parental L. casei Zhang and its descendent cells in an antibiotics-containing environment to compare their global protein expression profiles using the iTRAQ-based proteomic approach. A total of 72 proteins were significantly up-regulated (>2.0-fold, P < 0.05), whilst 32 proteins were significantly down-regulated <−2.0-fold, P < 0.05) in the descendent line. The gentamycin-resistant descendent line showed elevated expression in some carbohydrates, amino acids, and purine metabolic pathways. Several stress-related proteins were also differentially expressed. Among them, one alkaline shock protein, asp23, was up-regulated most in the gentamycin-resistant strain (21.9-fold increase compared with the parental strain). The asp23 gene disruption mutant was significantly more sensitive to gentamycin compared with the wild type, suggesting an important role of this gene in developing the gentamycin-resistant phenotype in L. casei. Our report has described the adaptation of a probiotic strain that has acquired antibiotics resistance through long-term antibiotics exposure at the proteome level, and we revealed a novel mechanism of gentamycin resistance.
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Affiliation(s)
- Wenyi Zhang
- Key Laboratory of Dairy Biotechnology and Engineering, Ministry of Education, Key Laboratory of Dairy Products Processing, Ministry of Agriculture, Inner Mongolia Agricultural University, Hohhot, China
| | - Huiling Guo
- Key Laboratory of Dairy Biotechnology and Engineering, Ministry of Education, Key Laboratory of Dairy Products Processing, Ministry of Agriculture, Inner Mongolia Agricultural University, Hohhot, China
| | - Chenxia Cao
- Key Laboratory of Dairy Biotechnology and Engineering, Ministry of Education, Key Laboratory of Dairy Products Processing, Ministry of Agriculture, Inner Mongolia Agricultural University, Hohhot, China
| | - Lina Li
- Key Laboratory of Dairy Biotechnology and Engineering, Ministry of Education, Key Laboratory of Dairy Products Processing, Ministry of Agriculture, Inner Mongolia Agricultural University, Hohhot, China
| | - Lai-Yu Kwok
- Key Laboratory of Dairy Biotechnology and Engineering, Ministry of Education, Key Laboratory of Dairy Products Processing, Ministry of Agriculture, Inner Mongolia Agricultural University, Hohhot, China
| | - Heping Zhang
- Key Laboratory of Dairy Biotechnology and Engineering, Ministry of Education, Key Laboratory of Dairy Products Processing, Ministry of Agriculture, Inner Mongolia Agricultural University, Hohhot, China
| | - Zhihong Sun
- Key Laboratory of Dairy Biotechnology and Engineering, Ministry of Education, Key Laboratory of Dairy Products Processing, Ministry of Agriculture, Inner Mongolia Agricultural University, Hohhot, China
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Kirchner M, Schneider S. Gene expression control by Bacillus anthracis purine riboswitches. RNA (NEW YORK, N.Y.) 2017; 23:762-769. [PMID: 28209633 PMCID: PMC5393184 DOI: 10.1261/rna.058792.116] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/18/2016] [Accepted: 02/12/2017] [Indexed: 06/06/2023]
Abstract
In all kingdoms of life, cellular replication relies on the presence of nucleosides and nucleotides, the building blocks of nucleic acids and the main source of energy. In bacteria, the availability of metabolites sometimes directly regulates the expression of enzymes and proteins involved in purine salvage, biosynthesis, and uptake through riboswitches. Riboswitches are located in bacterial mRNAs and can control gene expression by conformational changes in response to ligand binding. We have established an inverse reporter gene system in Bacillus subtilis that allows us to monitor riboswitch-controlled gene expression. We used it to investigate the activity of five potential purine riboswitches from Bacillus anthracis in response to different purines and pyrimidines. Furthermore, in vitro studies on the aptamer domains of the riboswitches reveal their variation in guanine binding affinity ranging from namomolar to micromolar. These data do not only provide insight into metabolite sensing but can also aid in engineering artificial cell regulatory systems.
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Affiliation(s)
- Marion Kirchner
- Center for Integrated Protein Science at the Department of Chemistry, Technische Universität München, 85748 Garching, Germany
| | - Sabine Schneider
- Center for Integrated Protein Science at the Department of Chemistry, Technische Universität München, 85748 Garching, Germany
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Hohmann HP, van Dijl JM, Krishnappa L, Prágai Z. Host Organisms:Bacillus subtilis. Ind Biotechnol (New Rochelle N Y) 2016. [DOI: 10.1002/9783527807796.ch7] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Affiliation(s)
- Hans-Peter Hohmann
- Nutrition Innovation Center R&D Biotechnology; DSM Nutritional Products Ltd; Wurmisweg 576 CH-4303 Kaiseraugst Switzerland
| | - Jan M. van Dijl
- University of Groningen, University Medical Center Groningen; Department of Medical Microbiology; Hanzeplein 1 9700 RB Groningen The Netherlands
| | - Laxmi Krishnappa
- University of Groningen, University Medical Center Groningen; Department of Medical Microbiology; Hanzeplein 1 9700 RB Groningen The Netherlands
| | - Zoltán Prágai
- Nutrition Innovation Center R&D Biotechnology; DSM Nutritional Products Ltd; Wurmisweg 576 CH-4303 Kaiseraugst Switzerland
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Improving the catalytic efficiency of Bacillus pumilus CotA-laccase by site-directed mutagenesis. Appl Microbiol Biotechnol 2016; 101:1935-1944. [DOI: 10.1007/s00253-016-7962-1] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2016] [Revised: 10/10/2016] [Accepted: 10/24/2016] [Indexed: 10/20/2022]
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Watanabe Y, Yanai H, Kanagawa M, Suzuki S, Tamura S, Okada K, Baba S, Kumasaka T, Agari Y, Chen L, Fu ZQ, Chrzas J, Wang BC, Nakagawa N, Ebihara A, Masui R, Kuramitsu S, Yokoyama S, Sampei GI, Kawai G. Crystal structures of a subunit of the formylglycinamide ribonucleotide amidotransferase, PurS, from Thermus thermophilus, Sulfolobus tokodaii and Methanocaldococcus jannaschii. Acta Crystallogr F Struct Biol Commun 2016; 72:627-35. [PMID: 27487927 PMCID: PMC4973304 DOI: 10.1107/s2053230x1600978x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2016] [Accepted: 06/16/2016] [Indexed: 11/10/2022] Open
Abstract
The crystal structures of a subunit of the formylglycinamide ribonucleotide amidotransferase, PurS, from Thermus thermophilus, Sulfolobus tokodaii and Methanocaldococcus jannaschii were determined and their structural characteristics were analyzed. For PurS from T. thermophilus, two structures were determined using two crystals that were grown in different conditions. The four structures in the dimeric form were almost identical to one another despite their relatively low sequence identities. This is also true for all PurS structures determined to date. A few residues were conserved among PurSs and these are located at the interaction site with PurL and PurQ, the other subunits of the formylglycinamide ribonucleotide amidotransferase. Molecular-dynamics simulations of the PurS dimer as well as a model of the complex of the PurS dimer, PurL and PurQ suggest that PurS plays some role in the catalysis of the enzyme by its bending motion.
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Affiliation(s)
- Yuzo Watanabe
- Department of Life and Environmental Sciences, Faculty of Engineering, Chiba Institute of Technology, 2-17-1 Tsudanuma, Narashino, Chiba 275-0016, Japan
| | - Hisaaki Yanai
- RIKEN SPring-8 Center, Harima Institute, 1-1-1 Kouto, Sayo, Hyogo 679-5148, Japan
| | - Mayumi Kanagawa
- RIKEN SPring-8 Center, Harima Institute, 1-1-1 Kouto, Sayo, Hyogo 679-5148, Japan
| | - Sakiko Suzuki
- Department of Life and Environmental Sciences, Faculty of Engineering, Chiba Institute of Technology, 2-17-1 Tsudanuma, Narashino, Chiba 275-0016, Japan
| | - Satoko Tamura
- Department of Life and Environmental Sciences, Faculty of Engineering, Chiba Institute of Technology, 2-17-1 Tsudanuma, Narashino, Chiba 275-0016, Japan
| | - Kiyoshi Okada
- Department of Engineering Science, Graduate School of Informatics and Engineering, The University of Electro-Communications, 1-5-1 Chofugaoka, Chofu, Tokyo 182-8585, Japan
| | - Seiki Baba
- Structural Biology Group, SPring-8/JASRI, 1-1-1 Kouto, Sayo, Hyogo 679-5198, Japan
| | - Takashi Kumasaka
- Structural Biology Group, SPring-8/JASRI, 1-1-1 Kouto, Sayo, Hyogo 679-5198, Japan
| | - Yoshihiro Agari
- RIKEN SPring-8 Center, Harima Institute, 1-1-1 Kouto, Sayo, Hyogo 679-5148, Japan
| | - Lirong Chen
- Department of Biochemistry and Molecular Biology, University of Georgia, Athens, GA 30602, USA
| | - Zheng-Qing Fu
- Department of Biochemistry and Molecular Biology, University of Georgia, Athens, GA 30602, USA
- SER-CAT, Advanced Photon Source, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL 60439-4861, USA
| | - John Chrzas
- Department of Biochemistry and Molecular Biology, University of Georgia, Athens, GA 30602, USA
- SER-CAT, Advanced Photon Source, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL 60439-4861, USA
| | - Bi-Cheng Wang
- Department of Biochemistry and Molecular Biology, University of Georgia, Athens, GA 30602, USA
| | - Noriko Nakagawa
- Department of Biological Sciences, Graduate School of Science, Osaka University, 1-1 Machikaneyama-cho, Toyonaka, Osaka 560-0043, Japan
| | - Akio Ebihara
- RIKEN SPring-8 Center, Harima Institute, 1-1-1 Kouto, Sayo, Hyogo 679-5148, Japan
| | - Ryoji Masui
- Department of Biological Sciences, Graduate School of Science, Osaka University, 1-1 Machikaneyama-cho, Toyonaka, Osaka 560-0043, Japan
| | - Seiki Kuramitsu
- Department of Biological Sciences, Graduate School of Science, Osaka University, 1-1 Machikaneyama-cho, Toyonaka, Osaka 560-0043, Japan
| | - Shigeyuki Yokoyama
- RIKEN SPring-8 Center, Harima Institute, 1-1-1 Kouto, Sayo, Hyogo 679-5148, Japan
| | - Gen-ichi Sampei
- RIKEN SPring-8 Center, Harima Institute, 1-1-1 Kouto, Sayo, Hyogo 679-5148, Japan
- Department of Engineering Science, Graduate School of Informatics and Engineering, The University of Electro-Communications, 1-5-1 Chofugaoka, Chofu, Tokyo 182-8585, Japan
| | - Gota Kawai
- Department of Life and Environmental Sciences, Faculty of Engineering, Chiba Institute of Technology, 2-17-1 Tsudanuma, Narashino, Chiba 275-0016, Japan
- RIKEN SPring-8 Center, Harima Institute, 1-1-1 Kouto, Sayo, Hyogo 679-5148, Japan
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Overkamp W, Kuipers OP. Transcriptional Profile of Bacillus subtilis sigF-Mutant during Vegetative Growth. PLoS One 2015; 10:e0141553. [PMID: 26506528 PMCID: PMC4624776 DOI: 10.1371/journal.pone.0141553] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2015] [Accepted: 10/09/2015] [Indexed: 11/18/2022] Open
Abstract
Sigma factor F is the first forespore specific transcription factor in Bacillus subtilis and controls genes required for the early stages of prespore development. The role of sigF is well studied under conditions that induce sporulation. Here, the impact of sigF disruption on the transcriptome of exponentially growing cultures is studied by micro-array analysis. Under these conditions that typically don’t induce sporulation, the transcriptome showed minor signs of sporulation initiation. The number of genes differentially expressed and the magnitude of expression were, as expected, quite small in comparison with sporulation conditions. The genes mildly down-regulated were mostly involved in anabolism and the genes mildly up-regulated, in particular fatty acid degradation genes, were mostly involved in catabolism. This is probably related to the arrest at sporulation stage II occurring in the sigF mutant, because continuation of growth from the formed disporic sporangia may require additional energy. The obtained knowledge is relevant for various experiments, such as industrial fermentation, prolonged experimental evolution or zero-growth studies, where sporulation is an undesirable trait that should be avoided, e.g by a sigF mutation.
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Affiliation(s)
- Wout Overkamp
- Department of Molecular Genetics, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Groningen, The Netherlands
- Kluyver Centre for Genomics of Industrial Fermentation, Delft, The Netherlands
| | - Oscar P. Kuipers
- Department of Molecular Genetics, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Groningen, The Netherlands
- Kluyver Centre for Genomics of Industrial Fermentation, Delft, The Netherlands
- * E-mail:
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Irla M, Neshat A, Brautaset T, Rückert C, Kalinowski J, Wendisch VF. Transcriptome analysis of thermophilic methylotrophic Bacillus methanolicus MGA3 using RNA-sequencing provides detailed insights into its previously uncharted transcriptional landscape. BMC Genomics 2015; 16:73. [PMID: 25758049 PMCID: PMC4342826 DOI: 10.1186/s12864-015-1239-4] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2014] [Accepted: 01/12/2015] [Indexed: 01/27/2023] Open
Abstract
Background Bacillus methanolicus MGA3 is a thermophilic, facultative ribulose monophosphate (RuMP) cycle methylotroph. Together with its ability to produce high yields of amino acids, the relevance of this microorganism as a promising candidate for biotechnological applications is evident. The B. methanolicus MGA3 genome consists of a 3,337,035 nucleotides (nt) circular chromosome, the 19,174 nt plasmid pBM19 and the 68,999 nt plasmid pBM69. 3,218 protein-coding regions were annotated on the chromosome, 22 on pBM19 and 82 on pBM69. In the present study, the RNA-seq approach was used to comprehensively investigate the transcriptome of B. methanolicus MGA3 in order to improve the genome annotation, identify novel transcripts, analyze conserved sequence motifs involved in gene expression and reveal operon structures. For this aim, two different cDNA library preparation methods were applied: one which allows characterization of the whole transcriptome and another which includes enrichment of primary transcript 5′-ends. Results Analysis of the primary transcriptome data enabled the detection of 2,167 putative transcription start sites (TSSs) which were categorized into 1,642 TSSs located in the upstream region (5′-UTR) of known protein-coding genes and 525 TSSs of novel antisense, intragenic, or intergenic transcripts. Firstly, 14 wrongly annotated translation start sites (TLSs) were corrected based on primary transcriptome data. Further investigation of the identified 5′-UTRs resulted in the detailed characterization of their length distribution and the detection of 75 hitherto unknown cis-regulatory RNA elements. Moreover, the exact TSSs positions were utilized to define conserved sequence motifs for translation start sites, ribosome binding sites and promoters in B. methanolicus MGA3. Based on the whole transcriptome data set, novel transcripts, operon structures and mRNA abundances were determined. The analysis of the operon structures revealed that almost half of the genes are transcribed monocistronically (940), whereas 1,164 genes are organized in 381 operons. Several of the genes related to methylotrophy had highly abundant transcripts. Conclusion The extensive insights into the transcriptional landscape of B. methanolicus MGA3, gained in this study, represent a valuable foundation for further comparative quantitative transcriptome analyses and possibly also for the development of molecular biology tools which at present are very limited for this organism. Electronic supplementary material The online version of this article (doi:10.1186/s12864-015-1239-4) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Marta Irla
- Genetics of Prokaryotes, Faculty of Biology & Center for Biotechnology, Bielefeld University, Universitätsstr. 25, 33615, Bielefeld, Germany.
| | - Armin Neshat
- Microbial Genomics and Biotechnology, Center for Biotechnology, Bielefeld University, Universitätstr. 27, 33615, Bielefeld, Germany.
| | - Trygve Brautaset
- Department of Molecular Biology, SINTEF Materials and Chemistry, Sem Selands vei 2, 7465, Trondheim, Norway. .,Department of Biotechnology, Norwegian University of Science and Technology, Sem Sælands vei 6/8, 7491, Trondheim, Norway.
| | - Christian Rückert
- Microbial Genomics and Biotechnology, Center for Biotechnology, Bielefeld University, Universitätstr. 27, 33615, Bielefeld, Germany. .,Technology Platform Genomics, Center for Biotechnology, Bielefeld University, Universitätsstr. 27, 33615, Bielefeld, Germany.
| | - Jörn Kalinowski
- Microbial Genomics and Biotechnology, Center for Biotechnology, Bielefeld University, Universitätstr. 27, 33615, Bielefeld, Germany. .,Technology Platform Genomics, Center for Biotechnology, Bielefeld University, Universitätsstr. 27, 33615, Bielefeld, Germany.
| | - Volker F Wendisch
- Genetics of Prokaryotes, Faculty of Biology & Center for Biotechnology, Bielefeld University, Universitätsstr. 25, 33615, Bielefeld, Germany.
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GTP dysregulation in Bacillus subtilis cells lacking (p)ppGpp results in phenotypic amino acid auxotrophy and failure to adapt to nutrient downshift and regulate biosynthesis genes. J Bacteriol 2013; 196:189-201. [PMID: 24163341 DOI: 10.1128/jb.00918-13] [Citation(s) in RCA: 74] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The nucleotide (p)ppGpp inhibits GTP biosynthesis in the Gram-positive bacterium Bacillus subtilis. Here we examined how this regulation allows cells to grow in the absence of amino acids. We showed that B. subtilis cells lacking (p)ppGpp, due to either deletions or point mutations in all three (p)ppGpp synthetase genes, yjbM, ywaC, and relA, strongly require supplementation of leucine, isoleucine, valine, methionine, and threonine and modestly require three additional amino acids. This polyauxotrophy is rescued by reducing GTP levels. Reduction of GTP levels activates transcription of genes responsible for the biosynthesis of the five strongly required amino acids by inactivating the transcription factor CodY, which represses the ybgE, ilvD, ilvBHC-leuABCD, ilvA, ywaA, and hom-thrCB operons, and by a CodY-independent activation of transcription of the ilvA, ywaA, hom-thrCB, and metE operons. Interestingly, providing the eight required amino acids does not allow for colony formation of (p)ppGpp(0) cells when transitioning from amino acid-replete medium to amino acid-limiting medium, and we found that this is due to an additional role that (p)ppGpp plays in protecting cells during nutrient downshifts. We conclude that (p)ppGpp allows adaptation to amino acid limitation by a combined effect of preventing death during metabolic transitions and sustaining growth by activating amino acid biosynthesis. This ability of (p)ppGpp to integrate a general stress response with a targeted reprogramming of gene regulation allows appropriate adaptation and is likely conserved among diverse bacteria.
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Identification of the bacteriocin subtilosin A and loss of purL results in its high-level production in Bacillus amyloliquefaciens. Res Microbiol 2012; 163:470-8. [DOI: 10.1016/j.resmic.2012.05.009] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2012] [Accepted: 05/22/2012] [Indexed: 11/17/2022]
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Suzuki S, Yanai H, Kanagawa M, Tamura S, Watanabe Y, Fuse K, Baba S, Sampei GI, Kawai G. Structure of N-formylglycinamide ribonucleotide amidotransferase II (PurL) from Thermus thermophilus HB8. Acta Crystallogr Sect F Struct Biol Cryst Commun 2011; 68:14-9. [PMID: 22232163 DOI: 10.1107/s1744309111048184] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2011] [Accepted: 11/14/2011] [Indexed: 11/10/2022]
Abstract
The crystal structure of PurL from Thermus thermophilus HB8 (TtPurL; TTHA1519) was determined in complex with an adenine nucleotide, PO(4)(3-) and Mg(2+) at 2.35 Å resolution. TtPurL consists of 29 α-helices and 28 β-strands, and one loop is disordered. TtPurL consists of four domains, A1, A2, B1 and B2, and the structures of the A1-B1 and A2-B2 domains were almost identical to each other. Although the sequence identity between TtPurL and PurL from Thermotoga maritima (TmPurL) is higher than that between TtPurL and the PurL domain of the large PurL from Salmonella typhimurium (StPurL), the secondary structure of TtPurL is much more similar to that of StPurL than to that of TmPurL.
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Affiliation(s)
- Sakiko Suzuki
- Department of Life and Environmental Sciences, Faculty of Engineering, Chiba Institute of Technology, Narashino, Chiba 275-0016, Japan
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Nannapaneni P, Hertwig F, Depke M, Hecker M, Mäder U, Völker U, Steil L, van Hijum SAFT. Defining the structure of the general stress regulon of Bacillus subtilis using targeted microarray analysis and random forest classification. MICROBIOLOGY-SGM 2011; 158:696-707. [PMID: 22174379 DOI: 10.1099/mic.0.055434-0] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The structure of the SigB-dependent general stress regulon of Bacillus subtilis has previously been characterized by proteomics approaches as well as DNA array-based expression studies. However, comparing the SigB targets published in three previous major transcriptional profiling studies it is obvious that although each of them identified well above 100 target genes, only 67 were identified in all three studies. These substantial differences can likely be attributed to the different strains, growth conditions, microarray platforms and experimental setups used in the studies. In order to gain a better understanding of the structure of this important regulon, a targeted DNA microarray analysis covering most of the known SigB-inducing conditions was performed, and the changes in expression kinetics of 252 potential members of the SigB regulon and appropriate control genes were recorded. Transcriptional data for the B. subtilis wild-type strain 168 and its isogenic sigB mutant BSM29 were analysed using random forest, a machine learning algorithm, by incorporating the knowledge from previous studies. This analysis revealed a strictly SigB-dependent expression pattern for 166 genes following ethanol, butanol, osmotic and oxidative stress, low-temperature growth and heat shock, as well as limitation of oxygen or glucose. Kinetic analysis of the data for the wild-type strain identified 30 additional members of the SigB regulon, which were also subject to control by additional transcriptional regulators, thus displaying atypical SigB-independent induction patterns in the mutant strain under some of the conditions tested. For 19 of these 30 SigB regulon members, published reports support control by secondary regulators along with SigB. Thus, this microarray-based study assigns a total of 196 genes to the SigB-dependent general stress regulon of B. subtilis.
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Affiliation(s)
- Priyanka Nannapaneni
- Interfakultäres Institut für Genetik und Funktionelle Genomforschung, Ernst-Moritz-Arndt-Universität Greifswald, Germany
| | - Falk Hertwig
- Interfakultäres Institut für Genetik und Funktionelle Genomforschung, Ernst-Moritz-Arndt-Universität Greifswald, Germany
| | - Maren Depke
- Interfakultäres Institut für Genetik und Funktionelle Genomforschung, Ernst-Moritz-Arndt-Universität Greifswald, Germany
| | - Michael Hecker
- Institut für Mikrobiologie, Ernst-Moritz-Arndt-Universität Greifswald, Germany
| | - Ulrike Mäder
- Interfakultäres Institut für Genetik und Funktionelle Genomforschung, Ernst-Moritz-Arndt-Universität Greifswald, Germany
| | - Uwe Völker
- Interfakultäres Institut für Genetik und Funktionelle Genomforschung, Ernst-Moritz-Arndt-Universität Greifswald, Germany
| | - Leif Steil
- Interfakultäres Institut für Genetik und Funktionelle Genomforschung, Ernst-Moritz-Arndt-Universität Greifswald, Germany
| | - Sacha A F T van Hijum
- NIZO Food Research, PO Box 20, 6710 BA Ede, The Netherlands.,Radboud University Nijmegen Medical Centre, Center for Molecular and Biomolecular Informatics, Nijmegen Center for Molecular Life Sciences, PO Box 9101, 6500 HB Nijmegen, The Netherlands.,Interfakultäres Institut für Genetik und Funktionelle Genomforschung, Ernst-Moritz-Arndt-Universität Greifswald, Germany
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Abstract
Bacillus anthracis, the etiological agent of anthrax, is a spore-forming, Gram-positive bacterium and a category A biothreat agent. Screening of a library of transposon-mutagenized B. anthracis spores identified a mutant displaying an altered phenotype that harbored a mutated gene encoding the purine biosynthetic enzyme PurH. PurH is a bifunctional protein that catalyzes the final steps in the biosynthesis of the purine IMP. We constructed and characterized defined purH mutants of the virulent B. anthracis Ames strain. The virulence of the purH mutants was assessed in guinea pigs, mice, and rabbits. The spores of the purH mutants were as virulent as wild-type spores in mouse intranasal and rabbit subcutaneous infection models but were partially attenuated in a mouse intraperitoneal model. In contrast, the purH mutant spores were highly attenuated in guinea pigs regardless of the administration route. The reduced virulence in guinea pigs was not due solely to a germination defect, since both bacilli and toxins were detected in vivo, suggesting that the significant attenuation was associated with a growth defect in vivo. We hypothesize that an intact purine biosynthetic pathway is required for the virulence of B. anthracis in guinea pigs.
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Molecular cloning, characterization and expression analysis of adenylosuccinate lyase gene in grass carp (Ctenopharyngodon idella). Mol Biol Rep 2010; 38:2059-65. [DOI: 10.1007/s11033-010-0331-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2009] [Accepted: 09/03/2010] [Indexed: 10/19/2022]
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Accumulation of gene-targeted Bacillus subtilis mutations that enhance fermentative inosine production. Appl Microbiol Biotechnol 2010; 87:2195-207. [PMID: 20524113 DOI: 10.1007/s00253-010-2646-8] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2010] [Revised: 04/21/2010] [Accepted: 04/22/2010] [Indexed: 10/19/2022]
Abstract
In order to test a possible approach to enhance fermentative inosine production by Bacillus subtilis, seven gene-targeted mutations were introduced in the laboratory standard strain168 in a stepwise fashion. The mutations were employed in order to prevent inosine 5'-monophosphate (IMP) from being consumed for AMP and GMP synthesis, to minimize inosine degradation, and to expand the intracellular IMP pool. First, the genes for adenylosuccinate synthase (purA) and IMP dehydrogenase (guaB) were inactivated. Second, two genes for purine nucleoside phosphorylase, punA and deoD, were inactivated. Third, to enhance purine nucleotide biosynthesis, the pur operon repressor PurR and the 5'-UTR of the operon, containing the guanine riboswitch, were disrupted. Finally, the -10 sequence of the pur promoter was optimized to elevate its transcription level. The resulting mutant was capable of producing 6 g/L inosine from 30 g/L glucose in culture broth without the detectable by-production of hypoxanthine. This indicates the validity of this approach for the breeding of the next generation of B. subtilis strains for industrial nucleoside production.
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Phylogenetic clustering of 4 prevalent virulence genes in Orientia tsutsugamushi isolates from human patients. J Microbiol 2010; 48:124-8. [PMID: 20221740 DOI: 10.1007/s12275-009-0267-7] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2009] [Accepted: 10/26/2009] [Indexed: 10/19/2022]
Abstract
The pathogenicity of microbes is involved in many kinds of virulence genes. The relationships between these virulence genes and strains are not clear in Orientia tsutsugamushi yet. In this study, we confirmed the presence of the virulence genes and classified into O. tsutsugamushi isolates using phylogenetic analysis of the virulence genes. We also compared the fatality rates of every isolate via an infection experiment in BALB/c mice using the O. tsutsugamushi isolates, Deajeon03-01, Wonju03-01, and Muju03-01. Moreover, we compared the phylogenetic analysis, in basis with 56 kDa protein sequence which determined from serotype, and virulence genes of O. tsutsugamushi. Our results showed remarkably different fatality rates between Deajeon03-01 and Muju03-01, which are both Boryong strains of O. tsutsugamushi. Also, clustering analyses including these two isolates gave slightly different results depending on whether they were clustered based on virulence genes or on the 56 kDa protein sequences. Consequently, we conclude that fatality rates in O. tsutsugamushi are correlated with differences in both serotypes and virulence genes. We identified some variations within the virulence genes dnaA, virB8, tolR, and trxA among the isolates.
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Heavy involvement of stringent transcription control depending on the adenine or guanine species of the transcription initiation site in glucose and pyruvate metabolism in Bacillus subtilis. J Bacteriol 2010; 192:1573-85. [PMID: 20081037 DOI: 10.1128/jb.01394-09] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
In Bacillus subtilis cells, the GTP level decreases and the ATP level increases upon a stringent response. This reciprocal change in the concentrations of the substrates of RNA polymerase affects the rate of transcription initiation of certain stringent genes depending on the purine species at their transcription initiation sites. DNA microarray analysis suggested that not only the rrn and ilv-leu genes encoding rRNAs and the enzymes for synthesis of branched-chain amino acids, respectively, but also many genes, including genes involved in glucose and pyruvate metabolism, might be subject to this kind of stringent transcription control. Actually, the ptsGHI and pdhABCD operons encoding the glucose-specific phosphoenolpyruvate:sugar phosphotransferase system and the pyruvate dehydrogenase complex were found to be negatively regulated, like rrn, whereas the pycA gene encoding pyruvate carboxylase and the alsSD operon for synthesis of acetoin from pyruvate were positively regulated, like ilv-leu. Replacement of the guanine at position 1 and/or position 2 of ptsGHI and at position 1 of pdhABCD (transcription initiation base at position 1) by adenine changed the negative stringent control of these operons in the positive direction. The initiation bases for transcription of pdhABCD and pycA were newly determined. Then the promoter sequences of these stringent operons were aligned, and the results suggested that the presence of a guanine(s) and the presence of an adenine(s) at position 1 and/or position 2 might be indispensable for negative and positive stringent control, respectively. Such stringent transcription control that affects the transcription initiation rate through reciprocal changes in the GTP and ATP levels likely occurs for numerous genes of B. subtilis.
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31
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Increased production of riboflavin by metabolic engineering of the purine pathway in Bacillus subtilis. Biochem Eng J 2009. [DOI: 10.1016/j.bej.2009.04.008] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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32
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An adenosine kinase exists in Xanthomonas campestris pathovar campestris and is involved in extracellular polysaccharide production, cell motility, and virulence. J Bacteriol 2009; 191:3639-48. [PMID: 19329636 DOI: 10.1128/jb.00009-09] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Adenosine kinase (ADK) is a purine salvage enzyme and a typical housekeeping enzyme in eukaryotes which catalyzes the phosphorylation of adenosine to form AMP. Since prokaryotes synthesize purines de novo and no endogenous ADK activity is detectable in Escherichia coli, ADK has long been considered to be rare in bacteria. To date, only two prokaryotes, both of which are gram-positive bacteria, have been reported to contain ADK. Here we report that the gram-negative bacterium Xanthomonas campestris pathovar campestris, the causal agent of black rot of crucifers, possesses a gene (designated adk(Xcc)) encoding an ADK (named ADK(Xcc)), and we demonstrate genetically that the ADK(Xcc) is involved in extracellular polysaccharide (EPS) production, cell motility, and pathogenicity of X. campestris pv. campestris. adk(Xcc) was overexpressed as a His(6)-tagged protein in E. coli, and the purified His(6)-tagged protein exhibited ADK activity. Mutation of adk(Xcc) did not affect bacterial growth in rich and minimal media but led to an accumulation of intracellular adenosine and diminutions of intracellular ADK activity and ATP level, as well as EPS. The adk(Xcc) mutant displayed significant reductions in bacterial growth and virulence in the host plant.
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33
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Modeling the noncovalent interactions at the metabolite binding site in purine riboswitches. J Mol Model 2009; 15:633-49. [PMID: 19137333 DOI: 10.1007/s00894-008-0384-y] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2008] [Accepted: 10/08/2008] [Indexed: 12/25/2022]
Abstract
We present gas phase quantum chemical studies on the metabolite binding interactions in two important purine riboswitches, the adenine and guanine riboswitches, at the B3LYP/6-31G(d,p) level of theory. In order to gain insights into the strucutral basis of their discriminative abilities of regulating gene expression, the structural properties and binding energies for the gas phase optimized geometries of the metabolite bound binding pocket are analyzed and compared with their respective crystal geometries. Kitaura-Morokuma analysis has been carried out to calculate and decompose the interaction energy into various components. NBO and AIM analysis has been carried out to understand the strength and nature of binding of the individual aptamer bases with their respective purine metabolites. The Y74 base, U in case of adenine riboswitch and C in case of guanine riboswitch constitutes the only differentiating element between the two binding pockets. As expected, with W:W cis G:C74 interaction contributing more than 50% of the total binding energy, the interaction energy for metabolite binding as calculated for guanine (-46.43 Kcal/mol) is nearly double compared to the corresponding value for that of adenine (-24.73 Kcal/mol) in the crystal context. Variations in the optimized geometries for different models and comparison of relative contribution to metabolite binding involving four conserved bases reveal the possible role of U47:U51 W:H trans pair in the conformational transition of the riboswitch from the metabolite free to metabolite bound state. Our results are also indicative of significant contributions from stacking and magnesium ion interactions toward cooperativity effects in metabolite recognition.
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34
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Kuehner JN, Brow DA. Regulation of a eukaryotic gene by GTP-dependent start site selection and transcription attenuation. Mol Cell 2008; 31:201-11. [PMID: 18657503 DOI: 10.1016/j.molcel.2008.05.018] [Citation(s) in RCA: 107] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2008] [Revised: 04/24/2008] [Accepted: 05/29/2008] [Indexed: 10/21/2022]
Abstract
Guanine nucleotide negatively regulates yeast inosine monophosphate dehydrogenase (IMPDH) mRNA synthesis by an unknown mechanism. IMPDH catalyzes the first dedicated step of GTP biosynthesis, and feedback control of its expression maintains the proper balance of purine nucleotides. Here we show that RNA polymerase II (Pol II) responds to GTP concentration. When GTP is sufficient, Pol II initiates transcription of the IMPDH gene (IMD2) at TATA box-proximal "G" sites, producing attenuated transcripts. When GTP is deficient, Pol II initiates at an "A" further downstream, circumventing the regulatory terminator to produce IMPDH mRNA. A major determinant for GTP concentration-dependent initiation at the upstream sites is the presence of guanine at the first and second positions of the transcript. Mutations in the Rpb1 subunit of Pol II and in TFIIB disrupt IMD2 regulation by altering start site selection. Thus, Pol II initiation can be regulated by the concentration of initiating nucleotide.
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Affiliation(s)
- Jason N Kuehner
- Cellular and Molecular Biology Graduate Program, University of Wisconsin School of Medicine and Public Health, Madison, WI 53706, USA
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35
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Ling PD, Tan J, Sewatanon J, Peng R. Murine gammaherpesvirus 68 open reading frame 75c tegument protein induces the degradation of PML and is essential for production of infectious virus. J Virol 2008; 82:8000-12. [PMID: 18508901 PMCID: PMC2519593 DOI: 10.1128/jvi.02752-07] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2007] [Accepted: 05/19/2008] [Indexed: 01/27/2023] Open
Abstract
Promyelocytic Leukemia nuclear body (PML NB) proteins mediate an intrinsic cellular host defense response against virus infections. Herpesviruses express proteins that modulate PML or PML-associated proteins by a variety of strategies, including degradation of PML or relocalization of PML NB proteins. The consequences of PML-herpesvirus interactions during infection in vivo have yet to be investigated in detail, largely because of the species-specific tropism of many human herpesviruses. Murine gammaherpesvirus 68 (gammaHV68) is emerging as a suitable model to study basic biological questions of virus-host interactions because it naturally infects mice. Therefore, we sought to determine whether gammaHV68 targets PML NBs as part of its natural life cycle. We found that gammaHV68 induces PML degradation through a proteasome-dependent mechanism and that loss of PML results in more robust virus replication in mouse fibroblasts. Surprisingly, gammaHV68-mediated PML degradation was mediated by the virion tegument protein ORF75c, which shares homology with the cellular formylglycinamide ribotide amidotransferase enzyme. In addition, we show that ORF75c is essential for production of infectious virus. ORF75 homologs are conserved in all rhadinoviruses but so far have no assigned functions. Our studies shed light on a potential role for this unusual protein in rhadinovirus biology and suggest that gammaHV68 will be a useful model for investigation of PML-herpesvirus interactions in vivo.
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Affiliation(s)
- Paul D Ling
- Department of Molecular Virology and Microbiology, Baylor College of Medicine, Mail Stop BCM-385, One Baylor Plaza, Houston, Texas 77030, USA.
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36
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Abstract
Purine nucleotides are critically important for the normal functioning of cells due to their myriad of activities. It is important for cells to maintain a balance in the pool sizes of the adenine-containing and guanine-containing nucleotides, which occurs by a combination of de novo synthesis and salvage pathways that interconvert the purine nucleotides. This review describes the mechanism for regulation of the biosynthetic genes in the yeast Saccharomyces cerevisiae and compares this mechanism with that described in several microbial species.
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Affiliation(s)
- R J Rolfes
- Department of Biology, Reiss Science Building 406, Georgetown University, Washington, DC 20057-1229, USA.
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37
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Fox PM, Climo MW, Archer GL. Lack of relationship between purine biosynthesis and vancomycin resistance in Staphylococcus aureus: a cautionary tale for microarray interpretation. Antimicrob Agents Chemother 2007; 51:1274-80. [PMID: 17242154 PMCID: PMC1855472 DOI: 10.1128/aac.01060-06] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Previous microarray data (E. Mongodin, J. Finan, M. W. Climo, A. Rosato, S. Gill, and G. L. Archer, J. Bacteriol. 185:4638-4643, 2003) noted an association in two vancomycin-intermediate Staphylococcus aureus (VISA) strains between high-level, passage-induced vancomycin resistance, a marked increase in the transcription of purine biosynthetic genes, and mutation of the putative purine regulator purR. Initial studies to report on the possible association between vancomycin resistance and alterations in purine metabolism in one of these strains (VP-32) confirmed, by Western analysis, an increase in the translation of PurH and PurM, two purine pathway enzymes. In addition, PurR was identified, by knockout and complementation in a vancomycin-susceptible strain, as a repressor of the purine biosynthetic operon in S. aureus, and the PurR missense mutation was shown to inactivate the repressor. However, despite the apparent relationship between increased purine biosynthesis and increased vancomycin resistance in VP-32, neither the addition of exogenous purines to a defined growth medium nor the truncation or inactivation of purR improved the growth of vancomycin-susceptible S. aureus in the presence of vancomycin. Furthermore, the passage of additional vancomycin-susceptible and VISA strains to high-level vancomycin resistance occurred without changes in cellular purine metabolism or mutation of purR despite the development of thickened cell walls in passaged strains. Thus, we could confirm neither a role for altered purine metabolism in the development of vancomycin resistance nor its requirement for the maintenance of a thickened cell wall. The failure of biochemical and physiological studies to support the association between transcription and phenotype initially found in careful microarray studies emphasizes the importance of follow-up investigations to confirm microarray observations.
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Affiliation(s)
- Paige M Fox
- Department of Microbiology and Immunology, Virginia Commonwealth University School of Medicine, and Hunter Holmes McGuire Veteran Affairs Medical Center, P.O. Box 980565, 1101 East Marshall Street, Richmond, VA 23298, USA
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38
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Zalkin H. The amidotransferases. ADVANCES IN ENZYMOLOGY AND RELATED AREAS OF MOLECULAR BIOLOGY 2006; 66:203-309. [PMID: 8430515 DOI: 10.1002/9780470123126.ch5] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Affiliation(s)
- H Zalkin
- Department of Biochemistry, Purdue University, West Lafayette, Indiana
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39
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Lee P, Colman RF. Expression, purification, and characterization of stable, recombinant human adenylosuccinate lyase. Protein Expr Purif 2006; 51:227-34. [PMID: 16973378 DOI: 10.1016/j.pep.2006.07.023] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2006] [Revised: 07/05/2006] [Accepted: 07/10/2006] [Indexed: 11/18/2022]
Abstract
The full length human adenylosuccinate lyase gene was generated by a PCR method using a plasmid encoding a truncated human enzyme as template, and was cloned into a pET-14b vector. Human adenylosuccinate lyase was overexpressed in Escherichia coli Rosetta 2(DE3)pLysS as an N-terminal histidine-tagged protein and was purified to homogeneity by a nickel-nitriloacetic acid column at room temperature. The histidine tag was removed from the human enzyme by thrombin digestion and the adenylosuccinate lyase was purified by Sephadex G-100 gel filtration. The histidine-tagged and non-tagged adenylosuccinate lyases exhibit similar values of Vmax and Km for S-AMP. Analytical ultracentrifugation and circular dichroism revealed, respectively, that the histidine-tagged enzyme is in tetrameric form with a molecular weight of 220 kDa and contains predominantly alpha-helical structure. This is the first purification procedure to yield a stable form of human adenylosuccinate lyase. The enzyme is stable for at least 5 days at 25 degrees C, and upon rapid freezing and thawing. Temperature as well as reducing agent (DTT) play critical roles in determining the stability of the human adenylosuccinate lyase.
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Affiliation(s)
- Peychii Lee
- Department of Chemistry and Biochemistry, University of Delaware, Newark, DE 19716, USA
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40
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Qian J, Cai X, Chu J, Zhuang Y, Zhang S. Nucleotide mutations in purA gene and pur operon promoter discovered in guanosine- and inosine-producing Bacillus subtilis strains. Biotechnol Lett 2006; 28:937-41. [PMID: 16786280 DOI: 10.1007/s10529-006-9020-z] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2005] [Accepted: 02/28/2006] [Indexed: 10/24/2022]
Abstract
The promoter region of the pur operon, which contains 12 genes for inosine monophosphate biosynthesis from phosphoribosylpyrophosphate, and the purA gene, encoding the adenylosuccinate synthetase, were compared among wild-type and three purine-producing Bacillus subtilis strains. A single nucleotide deletion at position 55 (relative to translation start site) in purA gene was found in a high inosine-producing strain and in a high guanosine-producing strain, which correlates with the absence of adenylosuccinate synthetase activity in these strains. Within the pur operon promoter of high guanosine-producing strain, in addition to a single nucleotide deletion in PurBox1 and a single nucleotide substitution in PurBox2, there were 4 substitutions in the flanking region of the PurBoxes and 32 nucleotide mutations in the 5' untranslated region. These mutations may explain the purine accumulation in purine-producing strains and be helpful to the rational design of high-yield recombinant strains.
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Affiliation(s)
- Jiangchao Qian
- State Key Laboratory of Bioreactor Engineering, East China University of Science & Technology, Shanghai, PR China.
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41
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Gilbert SD, Stoddard CD, Wise SJ, Batey RT. Thermodynamic and kinetic characterization of ligand binding to the purine riboswitch aptamer domain. J Mol Biol 2006; 359:754-68. [PMID: 16650860 DOI: 10.1016/j.jmb.2006.04.003] [Citation(s) in RCA: 227] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2006] [Revised: 03/31/2006] [Accepted: 04/01/2006] [Indexed: 01/06/2023]
Abstract
Riboswitches are cis-acting genetic regulatory elements found commonly in bacterial mRNAs that consist of a metabolite-responsive aptamer domain coupled to a regulatory switch. Purine riboswitches respond to intracellular concentrations of either adenine or guanine/hypoxanthine to control gene expression. The aptamer domain of the purine riboswitch contains a pyrimidine residue (Y74) that forms a Watson-Crick base-pairing interaction with the bound purine nucleobase ligand that discriminates between adenine and guanine. We sought to understand the structural basis of this specificity and the mechanism of ligand recognition by the purine riboswitch. Here, we present the 2,6-diaminopurine-bound structure of a C74U mutant of the xpt-pbuX guanine riboswitch, along with a detailed thermodynamic and kinetic analysis of nucleobase recognition by both the native and mutant riboswitches. These studies demonstrate clearly that the pyrimidine at position 74 is the sole determinant of purine riboswitch specificity. In addition, the mutant riboswitch binds adenine and adenine derivatives well compared with the guanine-responsive riboswitch. Under our experimental conditions, 2,6-diaminopurine binds the RNA with DeltaH=-40.3 kcal mol(-1), DeltaS=-97.6 cal mol(-1)K(-1), and DeltaG=-10.73 kcal mol(-1). A kinetic determination of the slow rate (0.15 x 10(5)M(-1)s(-1) and 2.1 x 10(5)mM(-1)s(-1) for 2-aminopurine binding the adenine-responsive mutant riboswitch and 7-deazaguanine-binding guanine riboswitch, respectively) of association under varying experimental conditions allowed us to propose a mechanism for ligand recognition by the purine riboswitch. A conformationally dynamic unliganded state for the binding pocket is stabilized first by the Watson-Crick base pairing between the ligand and Y74, and by the subsequent ordering of the J2/3 loop, enclosing the ligand within the three-way junction.
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Affiliation(s)
- Sunny D Gilbert
- Department of Chemistry and Biochemistry, University of Colorado, Boulder, Boulder, CO 80309, USA
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42
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Abstract
Riboswitches are structured domains that usually reside in the noncoding regions of mRNAs, where they bind metabolites and control gene expression. Like their protein counterparts, these RNA gene control elements form highly specific binding pockets for the target metabolite and undergo allosteric changes in structure. Numerous classes of riboswitches are present in bacteria and they comprise a common and robust metabolite-sensing system.
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Affiliation(s)
- Wade C Winkler
- Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, Texas 75390, USA.
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43
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Rappu P, Leppihalme M, Mäntsälä P. Mutational analysis of the Bacillus subtilis purA operator site. Curr Microbiol 2005; 51:322-6. [PMID: 16163456 DOI: 10.1007/s00284-005-0046-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2005] [Accepted: 04/25/2005] [Indexed: 11/26/2022]
Abstract
The Bacillus subtilis purine repressor, PurR, regulates many genes involved in purine metabolism. These genes contain a conserved 14-nucleotide inverted repeat (PurBox). Both pur operon and purA, which are regulated by PurR, have this inverted repeat with a 16- or 17-nucleotide spacer, respectively. Mutational studies have earlier shown that PurR binding is dependent on the PurBox of pur operon. In contrast, these studies failed to establish the importance of purA PurBox to PurR binding. To examine this inconsistency, we studied the effects of PurBox mutations both in vivo and in vitro. The data presented here indicate that purA PurBox has a similar role as pur operon PurBox in PurR binding. In addition, our data suggest that the previously proposed classification of the two halves of the Purbox into weak and strong may need to be revised.
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Affiliation(s)
- Pekka Rappu
- Department of Biochemistry and Food Chemistry, University of Turku, Vatselankatu 2, FI-20014, Turku, Finland.
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44
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Patterns of sequence divergence in 5' intergenic spacers and linked coding regions in 10 species of pathogenic bacteria reveal distinct recombinational histories. Genetics 2005; 168:1795-803. [PMID: 15611157 DOI: 10.1534/genetics.104.032979] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
We compared the pattern of nucleotide difference in 8034 genes and in their 5' intergenic spacers between conspecific pairs of genomes from 10 species of pathogenic bacteria. Certain genes or spacers showed much greater sequence divergence between the genotypes compared to others; such divergent regions plausibly originated by recombinational events by which a gene and/or spacers was donated from a divergent genome. Different patterns of divergence in genes and spacers identified different recombinational patterns. For example, in Chlamydophila pneumoniae, there were examples of both unusually divergent spacers and unusually divergent genes, but there were no cases in which a gene and its spacer were both unusually divergent. This pattern suggests that, in C. pneumoniae, recombination events have broken up the linkage between genes and 5' spacers. By contrast, in Streptococcus agalactiae, there were a number of cases in which both spacer and gene were unusually divergent, indicating that a number of large-scale recombination events that included both genes and 5' spacers have occurred; there was evidence of at least two large-scale recombination events in the genomic region including the pur genes in S. agalactiae.
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45
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Xuan J, Zalkin H, Weng M. Mutations in PurBox1 of the Bacillus subtilis pur operon control site affect adenine-regulated expression in vivo. SCIENCE IN CHINA. SERIES C, LIFE SCIENCES 2005; 48:133-8. [PMID: 15986885 DOI: 10.1007/bf02879665] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Transcription of the Bacillus subtilis pur operon is regulated by a purine repressor (PurR)-DNA control site interaction. The pur operon control site has two PurBoxes that are required for high-affinity PurR binding. An upstream, strong-binding PurBox1 is at position -81 to -68 relative to the transcription start site and a downstream weak-binding PurBox2 is at position -49 to -36. We constructed three PurBox1 mutations and the effects on binding of PurR to the control region in vitro and on regulation of pur operon expression in vivo were investigated. The mutations significantly reduced the binding of PurR to control region DNA. In strains with G-75A, G-75T and a five bp deletion (delta5) pur operon repression was defective in vivo. In addition in vivo PurR titration was used to confirm that sequences flanking PurBox1 and PurBox2 are required for PurR binding to the puroperon control site.
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Affiliation(s)
- Jinsong Xuan
- Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China
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46
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Nygaard P, Saxild HH. The purine efflux pump PbuE in Bacillus subtilis modulates expression of the PurR and G-box (XptR) regulons by adjusting the purine base pool size. J Bacteriol 2005; 187:791-4. [PMID: 15629952 PMCID: PMC543539 DOI: 10.1128/jb.187.2.791-794.2005] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
In Bacillus subtilis, the expression of genes encoding enzymes and other proteins involved in purine de novo synthesis and salvage is affected by purine bases and phosphoribosylpyrophosphate (PRPP). The transcription of the genes belonging to the PurR regulon is negatively regulated by the PurR protein and PRPP. The expression of the genes belonging to the G-box (XptR) regulon, including the pbuE gene, is negatively regulated by a riboswitch-controlled transcription termination mechanism. The G-box regulon effector molecules are hypoxanthine and guanine. pbuE encodes a purine base efflux pump and is now recognized as belonging to a third purine regulon. The expression of the pbuE gene is positively regulated by a riboswitch that recognizes adenine. Here we show that the expression of pbuE'-lacZ transcriptional fusions are induced by adenine to the highest extent in mutants which do not express a functional PbuE pump. In a mutant defective in the metabolism of adenine, the ade apt mutant, we found a high intracellular level of adenine and constitutive high levels of PbuE. A growth test using a purine auxotroph provided further evidence for the role of PbuE in lowering the intracellular concentration of purine bases, including adenine. Purine analogs also affect the expression of pbuE, which might be of importance for the protection against toxic analogs. In a mutant that overexpresses PbuE, the expression of genes belonging to the PurR regulon was increased. Our findings provide further evidence for important functions of the PbuE protein, such as acting as a pump that lowers the purine base pool and affects the expression of the G-box and PurR regulons, including pbuE itself, and as a pump involved in protection against toxic purine base analogs.
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Affiliation(s)
- Per Nygaard
- Institute of Molecular Biology, Department of Biological Chemistry, University of Copenhagen, Copenhagen, Denmark
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47
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Steiner-Mosonyi M, Creuzenet C, Keates RAB, Strub BR, Mangroo D. The Pseudomonas aeruginosa initiation factor IF-2 is responsible for formylation-independent protein initiation in P. aeruginosa. J Biol Chem 2004; 279:52262-9. [PMID: 15385567 DOI: 10.1074/jbc.m408086200] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Formylation of the initiator methionyl-tRNA (Met-tRNAfMet) was generally thought to be essential for initiation of protein synthesis in all eubacteria based on studies conducted primarily in Escherichia coli. However, this view of eubacterial protein initiation has changed because some bacteria have been demonstrated to have the capacity to initiate protein synthesis with the unformylated Met-tRNAfMet. Here we show that the Pseudomonas aeruginosa initiation factor IF-2 is required for formylation-independent protein initiation in P. aeruginosa, the first bacterium shown to have the ability to initiate protein synthesis with both the initiator formyl-methionyl-tRNA (fMet-tRNAfMet) and Met-tRNAfMet. The E. coli IF-2, which participates exclusively in formylation-dependent protein initiation in E. coli, was unable to facilitate utilization of Met-tRNAfMet in initiation in P. aeruginosa. However, the E. coli IF-2 was made to function in formylation-independent protein initiation in P. aeruginosa by decreasing the positive charge potential of the cleft that binds the amino end of the amino acid attached to the tRNA. Furthermore increasing the positive charge potential of this cleft in the P. aeruginosa IF-2 prevented the protein from participating in formylation-independent protein initiation. Thus, this is the first demonstration of a eubacterial IF-2 with an inherent capacity to facilitate utilization of Met-tRNAfMet in protein initiation, discounting the dogma that eubacterial IF-2 can only allow the use of fMet-tRNAfMet in protein initiation. Furthermore these findings give important clues to the basis for discriminating the initiator Met-tRNA by IF-2 and for the evolution of alternative mechanisms for discrimination.
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MESH Headings
- Amino Acid Sequence
- Bacterial Proteins/chemistry
- Bacterial Proteins/genetics
- Bacterial Proteins/metabolism
- Base Sequence
- DNA, Bacterial/genetics
- Escherichia coli/genetics
- Escherichia coli/metabolism
- Escherichia coli Proteins/chemistry
- Escherichia coli Proteins/genetics
- Escherichia coli Proteins/metabolism
- Genetic Complementation Test
- Models, Molecular
- Molecular Sequence Data
- Mutagenesis, Site-Directed
- Peptide Chain Initiation, Translational
- Prokaryotic Initiation Factor-2/chemistry
- Prokaryotic Initiation Factor-2/genetics
- Prokaryotic Initiation Factor-2/metabolism
- Protein Structure, Tertiary
- Pseudomonas aeruginosa/genetics
- Pseudomonas aeruginosa/metabolism
- RNA, Bacterial/genetics
- RNA, Bacterial/metabolism
- RNA, Transfer, Met/genetics
- RNA, Transfer, Met/metabolism
- Sequence Homology, Amino Acid
- Static Electricity
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Affiliation(s)
- Marta Steiner-Mosonyi
- Department of Molecular and Cellular Biology, University of Guelph, Ontario N1G 2W1, Canada
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48
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Hoskins AA, Anand R, Ealick SE, Stubbe J. The formylglycinamide ribonucleotide amidotransferase complex from Bacillus subtilis: metabolite-mediated complex formation. Biochemistry 2004; 43:10314-27. [PMID: 15301530 DOI: 10.1021/bi049127h] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Formylglycinamide ribonucleotide amidotransferase (FGAR-AT) catalyzes the ATP- and glutamine-dependent formation of formylglycinamidine ribonucleotide, ADP, P(i), and glutamate in the fourth step of de novo purine biosynthesis. Like all amidotransferases (ATs), FGAR-AT is proposed to channel ammonia between a glutaminase and AT domain. In Gram-negative bacteria and eukaryotes, FGAR-AT is a single approximately 140 kDa protein. In archae and Gram-positive bacteria, the FGAR-AT is formed from three proteins: PurS (10 kDa), PurQ (25 kDa, a glutaminase), and smPurL (80 kDa, an AT). This is the only known AT to require a third structural component (PurS) for activity. Here we report the first purification and biochemical characterization of a three-component AT from Bacillus subtilis. Efforts to isolate an intact FGAR-AT focused initially on coexpression of PurS, smPurL, and PurQ. However, all attempts to purify the complex resulted in separation of the constituent proteins. PurS, smPurL, and PurQ were therefore separately expressed and purified to homogeneity. PurQ had a glutaminase activity of 0.002 s(-1), and smPurL had an ammonia-dependent AT activity of 0.044 s(-1). Reconstitution of PurS, smPurL, and PurQ at a ratio of 2:1:1 gave an activity of 2.49 s(-1), similar to that previously reported for the Escherichia coli 140 kDa FGAR-AT (5.00 s(-1)). PurS was essential for the glutamine-dependent FGAR-AT activity. Surprisingly, activity was found to be absolutely dependent on the presence of Mg2+ and ADP, and a stable FGAR-AT complex of 2PurS/1smPurL/1PurQ was detected only in the presence of Mg2+, ADP, and glutamine. The implications of these observations are discussed with respect to ammonia channeling.
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Affiliation(s)
- Aaron A Hoskins
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
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49
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Serizawa M, Yamamoto H, Yamaguchi H, Fujita Y, Kobayashi K, Ogasawara N, Sekiguchi J. Systematic analysis of SigD-regulated genes in Bacillus subtilis by DNA microarray and Northern blotting analyses. Gene 2004; 329:125-36. [PMID: 15033535 DOI: 10.1016/j.gene.2003.12.024] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2003] [Revised: 10/27/2003] [Accepted: 12/23/2003] [Indexed: 11/22/2022]
Abstract
The SigD-regulated genes in Bacillus subtilis were systematically analyzed by comparing the pattern of transcripts derived from wild-type cells with those from sigD mutant cells using DNA microarray technology. One hundred and fifty-eight genes were found to be SigD-dependent candidates, 46 of which being known SigD-regulated genes. Northern blot analysis revealed that 18 of the remaining genes were SigD-dependent. The SigD consensus sequence was newly identified in the upstream regions of nine operons (11 genes): ybdO, yfmT-yfmS, hemAT, yjcP-yjcQ, yjfB, ylqB, yoaH, yscB and yxkC, and the other seven genes were assumed to be indirectly affected by a SigD mutation. Furthermore, yviE-yviF are likely to be SigD-dependent genes, because three independent sets of array data for yviE and yviF indicated they are SigD-dependent, and these genes are neighbors of flgL and hag transcribed by SigD RNA polymerase.
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Affiliation(s)
- Masakuni Serizawa
- Department of Applied Biology, Faculty of Textile Science and Technology, Shinshu University, 3-15-1 Tokida, Ueda, Nagano 386-8567, Japan
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50
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Affiliation(s)
- Maumita Mandal
- Department of Molecular, Cellular and Developmental Biology, Yale University, P.O. Box 208103, New Haven, Connecticut 06520-8103, USA
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