1
|
Mu X, Fu Y, Li P, Yu Y. In vitro activity of ceftolozane/tazobactam against Gram-negative bacilli isolated from pediatric patients: results from the Study for Monitoring Antimicrobial Resistance Trends (SMART) 2017-2021, China. J Glob Antimicrob Resist 2024:S2213-7165(24)00107-3. [PMID: 38908824 DOI: 10.1016/j.jgar.2024.05.017] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2023] [Revised: 05/15/2024] [Accepted: 05/20/2024] [Indexed: 06/24/2024] Open
Abstract
OBJECTIVES Ceftolozane-tazobactam (C/T) is a combination of a cephalosporin and a β-lactamase inhibitor with activity against Gram-negative bacilli (GNB). The study aims were to evaluate the activity of C/T in vitro vs. comparators against clinical GNB isolated from Chinese pediatric patients. METHODS From 2017-2021, 660 GNB isolates were collected from 20 hospitals across China. The minimum inhibitory concentrations were tested using a Trek Diagnostic System (Thermo Fisher Scientific). Susceptibility was determined by CLSI broth microdilution and the results were interpreted according to CLSI M100 (2021) breakpoints. RESULTS GNB isolates were obtained from pediatric patients < 18 years old, mainly from the bloodstream (n=146), intraperitoneal cavity (n=138), lower respiratory (n=278) and urinary tract (n=96). Overall, C/T was active against 76.6% of 436 Enterobacterales, with a descending susceptibility rate of 100.0% to S. marcescens, 92.2% to E. coli, 83.3% to K. oxytoca, 66.7% to K. aerogenes, 66.7% to P. mirabilis, 58.6% to K. pneumoniae and 57.1% to E. cloacae. The susceptibility of P. aeruginosa to C/T was 89.4%, which was the highest among the β-lactams and was second only to amikacin (92.9%). Isolates of respiratory tract infection (RTI) derived P. aeruginosa were highly susceptible (93.8%) to C/T, while < 75% of isolates of RTI derived P. aeruginosa were susceptible to the other β-lactams tested, except for ceftazidime-avibactam (91.2%). CONCLUSION GNBs collected from pediatric patients in China showed a high susceptibility to C/T making this drug combination an effective choice for treating the pediatric population, especially those infected with P. aeruginosa.
Collapse
Affiliation(s)
- Xinli Mu
- Department of Infectious Diseases, Sir Run Run Shaw Hospital, School of Medicine, Zhejiang University, Hangzhou, China.
| | - Ying Fu
- Department of Clinical Laboratory, Sir Run Run Shaw Hospital, School of Medicine, Zhejiang University, Hangzhou, China; Key Laboratory of Precision Medicine in Diagnosis and Monitoring Research of Zhejiang Province, Hangzhou, China.
| | - Pengcheng Li
- MRL Global Medical Affairs, MSD China, Shanghai, China.
| | - Yunsong Yu
- Department of Infectious Diseases, Sir Run Run Shaw Hospital, School of Medicine, Zhejiang University, Hangzhou, China; Key Laboratory of Microbial Technology and Bioinformatics of Zhejiang Province, Hangzhou, China; Regional Medical Center for National Institute of Respiratory Diseases, Sir Run Run Shaw Hospital, School of Medicine, Zhejiang University, Hangzhou, China.
| |
Collapse
|
2
|
Geiger CJ, Wong GCL, O'Toole GA. A bacterial sense of touch: T4P retraction motor as a means of surface sensing by Pseudomonas aeruginosa PA14. J Bacteriol 2024:e0044223. [PMID: 38832786 DOI: 10.1128/jb.00442-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/05/2024] Open
Abstract
Most microbial cells found in nature exist in matrix-covered, surface-attached communities known as biofilms. This mode of growth is initiated by the ability of the microbe to sense a surface on which to grow. The opportunistic pathogen Pseudomonas aeruginosa (Pa) PA14 utilizes a single polar flagellum and type 4 pili (T4P) to sense surfaces. For Pa, T4P-dependent "twitching" motility is characterized by effectively pulling the cell across a surface through a complex process of cooperative binding, pulling, and unbinding. T4P retraction is powered by hexameric ATPases. Pa cells that have engaged a surface increase production of the second messenger cyclic AMP (cAMP) over multiple generations via the Pil-Chp system. This rise in cAMP allows cells and their progeny to become better adapted for surface attachment and activates virulence pathways through the cAMP-binding transcription factor Vfr. While many studies have focused on mechanisms of T4P twitching and regulation of T4P production and function by the Pil-Chp system, the mechanism by which Pa senses and relays a surface-engagement signal to the cell is still an open question. Here we review the current state of the surface sensing literature for Pa, with a focus on T4P, and propose an integrated model of surface sensing whereby the retraction motor PilT senses and relays the signal to the Pil-Chp system via PilJ to drive cAMP production and adaptation to a surface lifestyle.
Collapse
Affiliation(s)
- C J Geiger
- Department of Microbiology and Immunology, Geisel School of Medicine at Dartmouth, Hanover, New Hampshire, USA
| | - G C L Wong
- Department of Bioengineering, University of California, Los Angeles, Los Angeles, California, USA
- Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, California, USA
- California NanoSystems Institute, University of California, Los Angeles, Los Angeles, California, USA
| | - G A O'Toole
- Department of Microbiology and Immunology, Geisel School of Medicine at Dartmouth, Hanover, New Hampshire, USA
| |
Collapse
|
3
|
Sung K, Park M, Chon J, Kweon O, Khan S. Unraveling the molecular dynamics of Pseudomonas aeruginosa biofilms at the air-liquid interface. Future Microbiol 2024; 19:681-696. [PMID: 38661712 DOI: 10.2217/fmb-2023-0234] [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: 10/23/2023] [Accepted: 01/31/2024] [Indexed: 04/26/2024] Open
Abstract
Aim: The aim of this study was to probe the dynamics of Pseudomonas aeruginosa PA14 air-liquid interface (ALI) biofilms over time through global proteomic analysis. Materials & methods: P. aeruginosa PA14 ALI biofilm samples, collected over 48-144 h, underwent differential expression analysis to identify varying proteins at each time point. Results: A consistent set of 778 proteins was identified, with variable expression over time. Upregulated proteins were mainly linked to 'amino acid transport and metabolism'. Biofilm-related pathways, including cAMP/Vfr and QS, underwent significant changes. Flagella were more influential than pili, especially in early biofilm development. Proteins associated with virulence, transporters and iron showed differential expression throughout. Conclusion: The findings enhance our understanding of ALI biofilm development.
Collapse
Affiliation(s)
- Kidon Sung
- Division of Microbiology, National Center for Toxicological Research, US FDA, Jefferson, AR 72079, USA
| | - Miseon Park
- Division of Microbiology, National Center for Toxicological Research, US FDA, Jefferson, AR 72079, USA
| | - Jungwhan Chon
- Department of Companion Animal Health, Inje University, Gimhae, South Korea
| | - Ohgew Kweon
- Division of Microbiology, National Center for Toxicological Research, US FDA, Jefferson, AR 72079, USA
| | - Saeed Khan
- Division of Microbiology, National Center for Toxicological Research, US FDA, Jefferson, AR 72079, USA
| |
Collapse
|
4
|
Strnad M, Rudenko N, Rego RO. Pathogenicity and virulence of Borrelia burgdorferi. Virulence 2023; 14:2265015. [PMID: 37814488 PMCID: PMC10566445 DOI: 10.1080/21505594.2023.2265015] [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: 11/09/2022] [Accepted: 09/25/2023] [Indexed: 10/11/2023] Open
Abstract
Infection with Borrelia burgdorferi often triggers pathophysiologic perturbations that are further augmented by the inflammatory responses of the host, resulting in the severe clinical conditions of Lyme disease. While our apprehension of the spatial and temporal integration of the virulence determinants during the enzootic cycle of B. burgdorferi is constantly being improved, there is still much to be discovered. Many of the novel virulence strategies discussed in this review are undetermined. Lyme disease spirochaetes must surmount numerous molecular and mechanical obstacles in order to establish a disseminated infection in a vertebrate host. These barriers include borrelial relocation from the midgut of the feeding tick to its body cavity and further to the salivary glands, deposition to the skin, haematogenous dissemination, extravasation from blood circulation system, evasion of the host immune responses, localization to protective niches, and establishment of local as well as distal infection in multiple tissues and organs. Here, the various well-defined but also possible novel strategies and virulence mechanisms used by B. burgdorferi to evade obstacles laid out by the tick vector and usually the mammalian host during colonization and infection are reviewed.
Collapse
Affiliation(s)
- Martin Strnad
- Biology Centre CAS, Institute of Parasitology, České Budějovice, Czech Republic
- Faculty of Science, University of South Bohemia, Branišovská, Czech Republic
| | - Natalie Rudenko
- Biology Centre CAS, Institute of Parasitology, České Budějovice, Czech Republic
| | - Ryan O.M. Rego
- Biology Centre CAS, Institute of Parasitology, České Budějovice, Czech Republic
- Faculty of Science, University of South Bohemia, Branišovská, Czech Republic
| |
Collapse
|
5
|
Pokorzynski ND, Groisman EA. How Bacterial Pathogens Coordinate Appetite with Virulence. Microbiol Mol Biol Rev 2023; 87:e0019822. [PMID: 37358444 PMCID: PMC10521370 DOI: 10.1128/mmbr.00198-22] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/27/2023] Open
Abstract
Cells adjust growth and metabolism to nutrient availability. Having access to a variety of carbon sources during infection of their animal hosts, facultative intracellular pathogens must efficiently prioritize carbon utilization. Here, we discuss how carbon source controls bacterial virulence, with an emphasis on Salmonella enterica serovar Typhimurium, which causes gastroenteritis in immunocompetent humans and a typhoid-like disease in mice, and propose that virulence factors can regulate carbon source prioritization by modifying cellular physiology. On the one hand, bacterial regulators of carbon metabolism control virulence programs, indicating that pathogenic traits appear in response to carbon source availability. On the other hand, signals controlling virulence regulators may impact carbon source utilization, suggesting that stimuli that bacterial pathogens experience within the host can directly impinge on carbon source prioritization. In addition, pathogen-triggered intestinal inflammation can disrupt the gut microbiota and thus the availability of carbon sources. By coordinating virulence factors with carbon utilization determinants, pathogens adopt metabolic pathways that may not be the most energy efficient because such pathways promote resistance to antimicrobial agents and also because host-imposed deprivation of specific nutrients may hinder the operation of certain pathways. We propose that metabolic prioritization by bacteria underlies the pathogenic outcome of an infection.
Collapse
Affiliation(s)
- Nick D. Pokorzynski
- Department of Microbial Pathogenesis, Yale School of Medicine, New Haven, Connecticut, USA
| | - Eduardo A. Groisman
- Department of Microbial Pathogenesis, Yale School of Medicine, New Haven, Connecticut, USA
- Yale Microbial Sciences Institute, West Haven, Connecticut, USA
| |
Collapse
|
6
|
Baek J, Yoon H. Cyclic di-GMP Modulates a Metabolic Flux for Carbon Utilization in Salmonella enterica Serovar Typhimurium. Microbiol Spectr 2023; 11:e0368522. [PMID: 36744926 PMCID: PMC10100716 DOI: 10.1128/spectrum.03685-22] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2022] [Accepted: 01/16/2023] [Indexed: 02/07/2023] Open
Abstract
Salmonella enterica serovar Typhimurium is an enteric pathogen spreading via the fecal-oral route. Transmission across humans, animals, and environmental reservoirs has forced this pathogen to rapidly respond to changing environments and adapt to new environmental conditions. Cyclic di-GMP (c-di-GMP) is a second messenger that controls the transition between planktonic and sessile lifestyles, in response to environmental cues. Our study reveals the potential of c-di-GMP to alter the carbon metabolic pathways in S. Typhimurium. Cyclic di-GMP overproduction decreased the transcription of genes that encode components of three phosphoenolpyruvate (PEP):carbohydrate phosphotransferase systems (PTSs) allocated for the uptake of glucose (PTSGlc), mannose (PTSMan), and fructose (PTSFru). PTS gene downregulation by c-di-GMP was alleviated in the absence of the three regulators, SgrS, Mlc, and Cra, suggesting their intermediary roles between c-di-GMP and PTS regulation. Moreover, Cra was found to bind to the promoters of ptsG, manX, and fruB. In contrast, c-di-GMP increased the transcription of genes important for gluconeogenesis. However, this effect of c-di-GMP in gluconeogenesis disappeared in the absence of Cra, indicating that Cra is a pivotal regulator that coordinates the carbon flux between PTS-mediated sugar uptake and gluconeogenesis, in response to cellular c-di-GMP concentrations. Since gluconeogenesis supplies precursor sugars required for extracellular polysaccharide production, Salmonella may exploit c-di-GMP as a dual-purpose signal that rewires carbon flux from glycolysis to gluconeogenesis and promotes biofilm formation using the end products of gluconeogenesis. This study sheds light on a new role for c-di-GMP in modulating carbon flux, to coordinate bacterial behavior in response to hostile environments. IMPORTANCE Cyclic di-GMP is a central signaling molecule that determines the transition between motile and nonmotile lifestyles in many bacteria. It stimulates biofilm formation at high concentrations but leads to biofilm dispersal and planktonic status at low concentrations. This study provides new insights into the role of c-di-GMP in programming carbon metabolic pathways. An increase in c-di-GMP downregulated the expression of PTS genes important for sugar uptake, while simultaneously upregulating the transcription of genes important for bacterial gluconeogenesis. The directly opposing effects of c-di-GMP on sugar metabolism were mediated by Cra (catabolite repressor/activator), a dual transcriptional regulator that modulates the direction of carbon flow. Salmonella may potentially harness c-di-GMP to promote its survival and fitness in hostile environments via the coordination of carbon metabolic pathways and the induction of biofilm formation.
Collapse
Affiliation(s)
- Jiwon Baek
- Department of Molecular Science and Technology, Ajou University, Suwon, Republic of Korea
| | - Hyunjin Yoon
- Department of Molecular Science and Technology, Ajou University, Suwon, Republic of Korea
- Department of Applied Chemistry and Biological Engineering, Ajou University, Suwon, Republic of Korea
| |
Collapse
|
7
|
Dela Ahator S, Liu Y, Wang J, Zhang LH. The virulence factor regulator and quorum sensing regulate the type I-F CRISPR-Cas mediated horizontal gene transfer in Pseudomonas aeruginosa. Front Microbiol 2022; 13:987656. [PMID: 36246261 PMCID: PMC9563714 DOI: 10.3389/fmicb.2022.987656] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2022] [Accepted: 09/12/2022] [Indexed: 11/13/2022] Open
Abstract
Pseudomonas aeruginosa is capable of thriving in diverse environments due to its network of regulatory components for effective response to stress factors. The survival of the bacteria is also dependent on the ability to discriminate between the acquisition of beneficial and non-beneficial genetic materials via horizontal gene transfer (HGT). Thus, bacteria have evolved the CRISPR-Cas adaptive immune system for defense against the deleterious effect of phage infection and HGT. By using the transposon mutagenesis approach, we identified the virulence factor regulator (Vfr) as a key regulator of the type I-F CRISPR-Cas system in P. aeruginosa. We showed that Vfr influences the expression of the CRISPR-Cas system through two signaling pathways in response to changes in calcium levels. Under calcium-rich conditions, Vfr indirectly regulates the CRISPR-Cas system via modulation of the AHL-QS gene expression, which could be vital for defense against phage infection at high cell density. When encountering calcium deficiency, however, Vfr can directly regulate the CRISPR-Cas system via a cAMP-dependent pathway. Furthermore, we provide evidence that mutation of vfr reduces the CRISPR-Cas spacer acquisition and interference of HGT. The results from this study add to the regulatory network of factors controlling the CRISPR-Cas system in response to abiotic factors in the environment. The findings may facilitate the design of effective and reliable phage therapies against P. aeruginosa infections, as targeting Vfr could prevent the development of the CRISPR-Cas mediated phage resistance.
Collapse
Affiliation(s)
- Stephen Dela Ahator
- Guangdong Province Key Laboratory of Microbial Signals and Disease Control, Integrative Microbiology Research Center, South China Agricultural University, Guangzhou, China
- Research Group for Host Microbe Interactions, Department of Medical Biology, Faculty of Health Sciences, UiT The Arctic University of Norway, Tromsø, Norway
| | - Yang Liu
- Guangdong Province Key Laboratory of Microbial Signals and Disease Control, Integrative Microbiology Research Center, South China Agricultural University, Guangzhou, China
- Centro de Biotecnología y Genómica de Plantas, Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (INIA), Universidad Politécnica de Madrid (UPM), Madrid, Spain
| | - Jianhe Wang
- Guangdong Province Key Laboratory of Microbial Signals and Disease Control, Integrative Microbiology Research Center, South China Agricultural University, Guangzhou, China
| | - Lian-Hui Zhang
- Guangdong Province Key Laboratory of Microbial Signals and Disease Control, Integrative Microbiology Research Center, South China Agricultural University, Guangzhou, China
- *Correspondence: Lian-Hui Zhang,
| |
Collapse
|
8
|
Stravoravdis S, Shipway JR, Goodell B. How Do Shipworms Eat Wood? Screening Shipworm Gill Symbiont Genomes for Lignin-Modifying Enzymes. Front Microbiol 2021; 12:665001. [PMID: 34322098 PMCID: PMC8312274 DOI: 10.3389/fmicb.2021.665001] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2021] [Accepted: 06/22/2021] [Indexed: 11/23/2022] Open
Abstract
Shipworms are ecologically and economically important mollusks that feed on woody plant material (lignocellulosic biomass) in marine environments. Digestion occurs in a specialized cecum, reported to be virtually sterile and lacking resident gut microbiota. Wood-degrading CAZymes are produced both endogenously and by gill endosymbiotic bacteria, with extracellular enzymes from the latter being transported to the gut. Previous research has predominantly focused on how these animals process the cellulose component of woody plant material, neglecting the breakdown of lignin – a tough, aromatic polymer which blocks access to the holocellulose components of wood. Enzymatic or non-enzymatic modification and depolymerization of lignin has been shown to be required in other wood-degrading biological systems as a precursor to cellulose deconstruction. We investigated the genomes of five shipworm gill bacterial symbionts obtained from the Joint Genome Institute Integrated Microbial Genomes and Microbiomes Expert Review for the production of lignin-modifying enzymes, or ligninases. The genomes were searched for putative ligninases using the Joint Genome Institute’s Function Profile tool and blastp analyses. The resulting proteins were then modeled using SWISS-MODEL. Although each bacterial genome possessed at least four predicted ligninases, the percent identities and protein models were of low quality and were unreliable. Prior research demonstrates limited endogenous ability of shipworms to modify lignin at the chemical/molecular level. Similarly, our results reveal that shipworm bacterial gill-symbiont enzymes are unlikely to play a role in lignin modification during lignocellulose digestion in the shipworm gut. This suggests that our understanding of how these keystone organisms digest and process lignocellulose is incomplete, and further research into non-enzymatic and/or other unknown mechanisms for lignin modification is required.
Collapse
Affiliation(s)
- Stefanos Stravoravdis
- Goodell Laboratory, Department of Microbiology, University of Massachusetts Amherst, Amherst, MA, United States
| | - J Reuben Shipway
- Goodell Laboratory, Department of Microbiology, University of Massachusetts Amherst, Amherst, MA, United States.,Centre for Enzyme Innovation, School of Biological Sciences, Institute of Biological and Biomedical Sciences, University of Portsmouth, Portsmouth, United Kingdom
| | - Barry Goodell
- Goodell Laboratory, Department of Microbiology, University of Massachusetts Amherst, Amherst, MA, United States
| |
Collapse
|
9
|
Ruksakiet K, Stercz B, Tóth G, Jaikumpun P, Gróf I, Tengölics R, Lohinai ZM, Horváth P, Deli MA, Steward MC, Dobay O, Zsembery Á. Bicarbonate Evokes Reciprocal Changes in Intracellular Cyclic di-GMP and Cyclic AMP Levels in Pseudomonas aeruginosa. BIOLOGY 2021; 10:biology10060519. [PMID: 34200909 PMCID: PMC8230467 DOI: 10.3390/biology10060519] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/17/2021] [Revised: 06/04/2021] [Accepted: 06/08/2021] [Indexed: 11/23/2022]
Abstract
The formation of Pseudomonas aeruginosa biofilms in cystic fibrosis (CF) is one of the most common causes of morbidity and mortality in CF patients. Cyclic di-GMP and cyclic AMP are second messengers regulating the bacterial lifestyle transition in response to environmental signals. We aimed to investigate the effects of extracellular pH and bicarbonate on intracellular c-di-GMP and cAMP levels, and on biofilm formation. P. aeruginosa was inoculated in a brain−heart infusion medium supplemented with 25 and 50 mM NaCl in ambient air (pH adjusted to 7.4 and 7.7 respectively), or with 25 and 50 mM NaHCO3 in 5% CO2 (pH 7.4 and 7.7). After 16 h incubation, c-di-GMP and cAMP were extracted and their concentrations determined. Biofilm formation was investigated using an xCelligence real-time cell analyzer and by crystal violet assay. Our results show that HCO3− exposure decreased c-di-GMP and increased cAMP levels in a dose-dependent manner. Biofilm formation was also reduced after 48 h exposure to HCO3−. The reciprocal changes in second messenger concentrations were not influenced by changes in medium pH or osmolality. These findings indicate that HCO3− per se modulates the levels of c-di-GMP and cAMP, thereby inhibiting biofilm formation and promoting the planktonic lifestyle of the bacteria.
Collapse
Affiliation(s)
- Kasidid Ruksakiet
- Department of Oral Biology, Semmelweis University, H-1089 Budapest, Hungary; (K.R.); (P.J.); (M.C.S.)
- Department of Conservative Dentistry, Semmelweis University, H-1085 Budapest, Hungary;
| | - Balázs Stercz
- Institute of Medical Microbiology, Faculty of Medicine, Semmelweis University, H-1089 Budapest, Hungary; (B.S.); (O.D.)
| | - Gergő Tóth
- Department of Pharmaceutical Chemistry, Semmelweis University, H-1092 Budapest, Hungary; (G.T.); (P.H.)
| | - Pongsiri Jaikumpun
- Department of Oral Biology, Semmelweis University, H-1089 Budapest, Hungary; (K.R.); (P.J.); (M.C.S.)
| | - Ilona Gróf
- Institute of Biophysics, Biological Research Centre, H-6726 Szeged, Hungary; (I.G.); (M.A.D.)
| | - Roland Tengölics
- Institute of Biochemistry, Biological Research Centre, H-6726 Szeged, Hungary;
- HCEMM-BRC Metabolic Systems Biology Laboratory, H-6726 Szeged, Hungary
| | - Zsolt M. Lohinai
- Department of Conservative Dentistry, Semmelweis University, H-1085 Budapest, Hungary;
| | - Péter Horváth
- Department of Pharmaceutical Chemistry, Semmelweis University, H-1092 Budapest, Hungary; (G.T.); (P.H.)
| | - Mária A. Deli
- Institute of Biophysics, Biological Research Centre, H-6726 Szeged, Hungary; (I.G.); (M.A.D.)
| | - Martin C. Steward
- Department of Oral Biology, Semmelweis University, H-1089 Budapest, Hungary; (K.R.); (P.J.); (M.C.S.)
- School of Medical Sciences, University of Manchester, Manchester M13 9PL, UK
| | - Orsolya Dobay
- Institute of Medical Microbiology, Faculty of Medicine, Semmelweis University, H-1089 Budapest, Hungary; (B.S.); (O.D.)
| | - Ákos Zsembery
- Department of Oral Biology, Semmelweis University, H-1089 Budapest, Hungary; (K.R.); (P.J.); (M.C.S.)
- Correspondence:
| |
Collapse
|
10
|
Arce-Rodríguez A, Nikel PI, Calles B, Chavarría M, Platero R, Krell T, de Lorenzo V. Low CyaA expression and anti-cooperative binding of cAMP to CRP frames the scope of the cognate regulon of Pseudomonas putida. Environ Microbiol 2021; 23:1732-1749. [PMID: 33559269 DOI: 10.1111/1462-2920.15422] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2020] [Revised: 01/09/2021] [Accepted: 02/02/2021] [Indexed: 12/29/2022]
Abstract
Although the soil bacterium Pseudomonas putida KT2440 bears a bona fide adenylate cyclase gene (cyaA), intracellular concentrations of 3',5'-cyclic adenosine monophosphate (cAMP) are barely detectable. By using reporter technology and direct quantification of cAMP under various conditions, we show that such low levels of the molecule stem from the stringent regulation of its synthesis, efflux and degradation. Poor production of cAMP was the result of inefficient translation of cyaA mRNA. Moreover, deletion of the cAMP-phosphodiesterase pde gene led to intracellular accumulation of the cyclic nucleotide, exposing an additional cause of cAMP drain in vivo. But even such low levels of the signal sustained activation of promoters dependent on the cAMP-receptor protein (CRP). Genetic and biochemical evidence indicated that the phenomenon ultimately rose from the unusual binding parameters of cAMP to CRP. This included an ultratight cAMP-CrpP. putida affinity (KD of 45.0 ± 3.4 nM) and an atypical 1:1 effector/dimer stoichiometry that obeyed an infrequent anti-cooperative binding mechanism. It thus seems that keeping the same regulatory parts and their relational logic but changing the interaction parameters enables genetic devices to take over entirely different domains of the functional landscape.
Collapse
Affiliation(s)
- Alejandro Arce-Rodríguez
- Department of Molecular Bacteriology, Helmholtz Centre for Infection Research, Braunschweig, 38124, Germany
| | - Pablo I Nikel
- The Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, Kongens Lyngby, 2800, Denmark
| | - Belén Calles
- Systems Biology Department, Centro Nacional de Biotecnología-CSIC, Campus de Cantoblanco, Madrid, 28049, Spain
| | - Max Chavarría
- Escuela de Química and CIPRONA, Universidad de Costa Rica, San José, 2060, Costa Rica
| | - Raúl Platero
- Departamento de Bioquímica y Genómica Microbianas, Instituto de Investigaciones Biológicas Clemente Estable, MEC, Montevideo, Uruguay
| | - Tino Krell
- Department of Environmental Protection, Estación Experimental del Zaidín CSIC, Granada, 18008, Spain
| | - Victor de Lorenzo
- Systems Biology Department, Centro Nacional de Biotecnología-CSIC, Campus de Cantoblanco, Madrid, 28049, Spain
| |
Collapse
|
11
|
Khannpnavar B, Mehta V, Qi C, Korkhov V. Structure and function of adenylyl cyclases, key enzymes in cellular signaling. Curr Opin Struct Biol 2020; 63:34-41. [PMID: 32334344 DOI: 10.1016/j.sbi.2020.03.003] [Citation(s) in RCA: 40] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2019] [Revised: 03/01/2020] [Accepted: 03/06/2020] [Indexed: 12/19/2022]
Abstract
The adenylyl cyclases (ACs) catalyze the production of the ubiquitous second messenger, cAMP, which in turns acts on a number of effectors and thus regulates a plethora of cellular functions. As the key enzymes in the highly evolutionarily conserved cAMP pathway, the ACs control the physiology of the cells, tissues, organs and organisms in health and disease. A comprehensive understanding of the specific role of the ACs in these processes of life requires a deep mechanistic understanding of structure and mechanisms of action of these enzymes. Here we highlight the exciting recent reports on the biochemistry and structure and higher order organization of the ACs and their signaling complexes. These studies have provided the glimpses into the principles of the AC-mediated homeostatic control of cellular physiology.
Collapse
Affiliation(s)
- Basavraj Khannpnavar
- Institute of Biochemistry, ETH Zurich, Switzerland; Laboratory of Biomolecular Research, Paul Scherrer Institute, Villigen 5232, Switzerland
| | - Ved Mehta
- Laboratory of Biomolecular Research, Paul Scherrer Institute, Villigen 5232, Switzerland
| | - Chao Qi
- Institute of Biochemistry, ETH Zurich, Switzerland; Laboratory of Biomolecular Research, Paul Scherrer Institute, Villigen 5232, Switzerland
| | - Volodymyr Korkhov
- Institute of Biochemistry, ETH Zurich, Switzerland; Laboratory of Biomolecular Research, Paul Scherrer Institute, Villigen 5232, Switzerland.
| |
Collapse
|
12
|
Muriel C, Blanco-Romero E, Trampari E, Arrebola E, Durán D, Redondo-Nieto M, Malone JG, Martín M, Rivilla R. The diguanylate cyclase AdrA regulates flagellar biosynthesis in Pseudomonas fluorescens F113 through SadB. Sci Rep 2019; 9:8096. [PMID: 31147571 PMCID: PMC6543031 DOI: 10.1038/s41598-019-44554-z] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2019] [Accepted: 05/14/2019] [Indexed: 11/23/2022] Open
Abstract
Flagellum mediated motility is an essential trait for rhizosphere colonization by pseudomonads. Flagella synthesis is a complex and energetically expensive process that is tightly regulated. In Pseudomonas fluorescens, the regulatory cascade starts with the master regulatory protein FleQ that is in turn regulated by environmental signals through the Gac/Rsm and SadB pathways, which converge in the sigma factor AlgU. AlgU is required for the expression of amrZ, encoding a FleQ repressor. AmrZ itself has been shown to modulate c-di-GMP levels through the control of many genes encoding enzymes implicated in c-di-GMP turnover. This cyclic nucleotide regulates flagellar function and besides, the master regulator of the flagellar synthesis signaling pathway, FleQ, has been shown to bind c-di-GMP. Here we show that AdrA, a diguanylate cyclase regulated by AmrZ participates in this signaling pathway. Epistasis analysis has shown that AdrA acts upstream of SadB, linking SadB with environmental signaling. We also show that SadB binds c-di-GMP with higher affinity than FleQ and propose that c-di-GMP produced by AdrA modulates flagella synthesis through SadB.
Collapse
Affiliation(s)
- Candela Muriel
- Departamento de Biología, Universidad Autónoma de Madrid, Campus de Cantoblanco, 28049, Madrid, Spain
| | - Esther Blanco-Romero
- Departamento de Biología, Universidad Autónoma de Madrid, Campus de Cantoblanco, 28049, Madrid, Spain
| | - Eleftheria Trampari
- Department of Molecular Microbiology, John Innes Centre. Colney Lane, Norwich, UK.,Quadram Institute, Norwich, UK
| | - Eva Arrebola
- Departamento de Biología, Universidad Autónoma de Madrid, Campus de Cantoblanco, 28049, Madrid, Spain.,Department of Microbiology, University of Málaga, Málaga, Spain
| | - David Durán
- Departamento de Biología, Universidad Autónoma de Madrid, Campus de Cantoblanco, 28049, Madrid, Spain
| | - Miguel Redondo-Nieto
- Departamento de Biología, Universidad Autónoma de Madrid, Campus de Cantoblanco, 28049, Madrid, Spain
| | - Jacob G Malone
- Department of Molecular Microbiology, John Innes Centre. Colney Lane, Norwich, UK
| | - Marta Martín
- Departamento de Biología, Universidad Autónoma de Madrid, Campus de Cantoblanco, 28049, Madrid, Spain
| | - Rafael Rivilla
- Departamento de Biología, Universidad Autónoma de Madrid, Campus de Cantoblanco, 28049, Madrid, Spain.
| |
Collapse
|
13
|
Jin Y, Zhang M, Zhu F, Peng Q, Weng Y, Zhao Q, Liu C, Bai F, Cheng Z, Jin S, Wu W. NrtR Regulates the Type III Secretion System Through cAMP/Vfr Pathway in Pseudomonas aeruginosa. Front Microbiol 2019; 10:85. [PMID: 30761117 PMCID: PMC6363681 DOI: 10.3389/fmicb.2019.00085] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2018] [Accepted: 01/16/2019] [Indexed: 11/23/2022] Open
Abstract
The type III secretion system (T3SS) plays an important role in the pathogenesis of Pseudomonas aeruginosa. Expression of the T3SS is controlled under a complicate regulatory network. In this study, we demonstrate that NrtR (PA4916) is involved in the T3SS expression and pathogenesis of P. aeruginosa in a mouse acute pneumonia model. Overexpression of the T3SS central activator ExsA or exogenous supplementation of cAMP restored the expression of T3SS in the ΔnrtR mutant, suggesting that NrtR might regulate T3SS through the cAMP-Vfr signaling pathway. Further experiments demonstrated that the decrease of cAMP content is not due to the expression change of adenylate cyclases or phosphodiesterase in the ΔnrtR mutant. As it has been shown that nadD2 is upregulated in the ΔnrtR mutant, we overexpressed nadD2 in wild type PAK, which reduced the intracellular cAMP level and the expression of the T3SS genes. Meanwhile, deletion of nadD2 in the ΔnrtR mutant restored the expression and secretion of the T3SS. Co-immunoprecipitation assay revealed an interaction between NadD2 and the catalytic domain of the adenylate cyclase CyaB. Further in vitro assay indicated that NadD2 repressed the enzymatic activity of CyaB. Therefore, we have identified a novel regulatory mechanism of T3SS in P. aeruginosa.
Collapse
Affiliation(s)
- Yongxin Jin
- State Key Laboratory of Medicinal Chemical Biology, Key Laboratory of Molecular Microbiology and Technology of the Ministry of Education, Department of Microbiology, College of Life Sciences, Nankai University, Tianjin, China
| | - Mengjing Zhang
- State Key Laboratory of Medicinal Chemical Biology, Key Laboratory of Molecular Microbiology and Technology of the Ministry of Education, Department of Microbiology, College of Life Sciences, Nankai University, Tianjin, China
| | - Feng Zhu
- State Key Laboratory of Medicinal Chemical Biology, Key Laboratory of Molecular Microbiology and Technology of the Ministry of Education, Department of Microbiology, College of Life Sciences, Nankai University, Tianjin, China
| | - Qianqian Peng
- State Key Laboratory of Medicinal Chemical Biology, Key Laboratory of Molecular Microbiology and Technology of the Ministry of Education, Department of Microbiology, College of Life Sciences, Nankai University, Tianjin, China
| | - Yuding Weng
- State Key Laboratory of Medicinal Chemical Biology, Key Laboratory of Molecular Microbiology and Technology of the Ministry of Education, Department of Microbiology, College of Life Sciences, Nankai University, Tianjin, China
| | - Qiang Zhao
- College of Life Sciences, Nankai University, Tianjin, China
| | - Chang Liu
- State Key Laboratory of Medicinal Chemical Biology, Key Laboratory of Molecular Microbiology and Technology of the Ministry of Education, Department of Microbiology, College of Life Sciences, Nankai University, Tianjin, China
| | - Fang Bai
- State Key Laboratory of Medicinal Chemical Biology, Key Laboratory of Molecular Microbiology and Technology of the Ministry of Education, Department of Microbiology, College of Life Sciences, Nankai University, Tianjin, China
| | - Zhihui Cheng
- State Key Laboratory of Medicinal Chemical Biology, Key Laboratory of Molecular Microbiology and Technology of the Ministry of Education, Department of Microbiology, College of Life Sciences, Nankai University, Tianjin, China
| | - Shouguang Jin
- Department of Molecular Genetics and Microbiology, College of Medicine, University of Florida, Gainesville, FL, United States
| | - Weihui Wu
- State Key Laboratory of Medicinal Chemical Biology, Key Laboratory of Molecular Microbiology and Technology of the Ministry of Education, Department of Microbiology, College of Life Sciences, Nankai University, Tianjin, China
| |
Collapse
|
14
|
Almblad H, Rybtke M, Hendiani S, Andersen JB, Givskov M, Tolker-Nielsen T. High levels of cAMP inhibit Pseudomonas aeruginosa biofilm formation through reduction of the c-di-GMP content. MICROBIOLOGY-SGM 2019; 165:324-333. [PMID: 30663958 DOI: 10.1099/mic.0.000772] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
The human pathogen Pseudomonas aeruginosa can cause both acute infections and chronic biofilm-based infections. Expression of acute virulence factors is positively regulated by cAMP, whereas biofilm formation is positively regulated by c-di-GMP. We provide evidence that increased levels of cAMP, caused by either a lack of degradation or increased production, inhibit P. aeruginosa biofilm formation. cAMP-mediated inhibition of P. aeruginosa biofilm formation required Vfr, and involved a reduction of the level of c-di-GMP, as well as reduced production of biofilm matrix components. A mutant screen and characterization of defined knockout mutants suggested that a subset of c-di-GMP-degrading phosphodiesterases is involved in cAMP-Vfr-mediated biofilm inhibition in P. aeruginosa.
Collapse
Affiliation(s)
- Henrik Almblad
- 1Costerton Biofilm Center, Department of Immunology and Microbiology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.,‡Present address: Department of Biological Sciences, University of Calgary, Calgary, AB, Canada
| | - Morten Rybtke
- 1Costerton Biofilm Center, Department of Immunology and Microbiology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Saghar Hendiani
- 2Department of Microbiology, School of Biology, College of Science, University of Tehran, Tehran, Iran
| | - Jens Bo Andersen
- 1Costerton Biofilm Center, Department of Immunology and Microbiology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Michael Givskov
- 1Costerton Biofilm Center, Department of Immunology and Microbiology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.,3Singapore Centre for Environmental Life Sciences Engineering, Nanyang Technological University, Singapore
| | - Tim Tolker-Nielsen
- 1Costerton Biofilm Center, Department of Immunology and Microbiology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| |
Collapse
|
15
|
Rossi E, Paroni M, Landini P. Biofilm and motility in response to environmental and host-related signals in Gram negative opportunistic pathogens. J Appl Microbiol 2018; 125:1587-1602. [PMID: 30153375 DOI: 10.1111/jam.14089] [Citation(s) in RCA: 55] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2018] [Revised: 05/30/2018] [Accepted: 07/20/2018] [Indexed: 12/13/2022]
Abstract
Most bacteria can switch between a planktonic, sometimes motile, form and a biofilm mode, in which bacterial cells can aggregate and attach to a solid surface. The transition between these two forms represents an example of bacterial adaptation to environmental signals and stresses. In 'environmental pathogens', namely, environmental bacteria that are also able to cause disease in animals and humans, signals associated either with the host or with the external environment, such as temperature, oxygen availability, nutrient concentrations etc., play a major role in triggering the switch between the motile and the biofilm mode, via complex regulatory mechanisms that control flagellar synthesis and motility, and production of adhesion factors. In this review article, we present examples of how environmental signals can impact biofilm formation and cell motility in the Gram negative bacteria Pseudomonas aeruginosa, Escherichia coli and in the Burkholderia genus, and how the switch between motile and biofilm mode can be an essential part of a more general process of adaptation either to the host or to the external environment.
Collapse
Affiliation(s)
- E Rossi
- Department of Clinical Microbiology, Rigshospitalet, København, Denmark
| | - M Paroni
- Department of Biosciences, Università degli Studi di Milano, Milan, Italy
| | - P Landini
- Department of Biosciences, Università degli Studi di Milano, Milan, Italy
| |
Collapse
|
16
|
Wiggins SV, Steegborn C, Levin LR, Buck J. Pharmacological modulation of the CO 2/HCO 3-/pH-, calcium-, and ATP-sensing soluble adenylyl cyclase. Pharmacol Ther 2018; 190:173-186. [PMID: 29807057 DOI: 10.1016/j.pharmthera.2018.05.008] [Citation(s) in RCA: 44] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Cyclic AMP (cAMP), the prototypical second messenger, has been implicated in a wide variety of (often opposing) physiological processes. It simultaneously mediates multiple, diverse processes, often within a single cell, by acting locally within independently-regulated and spatially-restricted microdomains. Within each microdomain, the level of cAMP will be dependent upon the balance between its synthesis by adenylyl cyclases and its degradation by phosphodiesterases (PDEs). In mammalian cells, there are many PDE isoforms and two types of adenylyl cyclases; the G protein regulated transmembrane adenylyl cyclases (tmACs) and the CO2/HCO3-/pH-, calcium-, and ATP-sensing soluble adenylyl cyclase (sAC). Discriminating the roles of individual cyclic nucleotide microdomains requires pharmacological modulators selective for the various PDEs and/or adenylyl cyclases. Such tools present an opportunity to develop therapeutics specifically targeted to individual cAMP dependent pathways. The pharmacological modulators of tmACs have recently been reviewed, and in this review, we describe the current status of pharmacological tools available for studying sAC.
Collapse
Affiliation(s)
- Shakarr V Wiggins
- Graduate Program in Neuroscience, Weill Cornell Medicine, New York, NY 10065, United States
| | - Clemens Steegborn
- Department of Biochemistry, University of Bayreuth, 95440 Bayreuth, Germany
| | - Lonny R Levin
- Department of Pharmacology, Weill Cornell Medicine, New York, NY 10065, United States.
| | - Jochen Buck
- Department of Pharmacology, Weill Cornell Medicine, New York, NY 10065, United States
| |
Collapse
|
17
|
Vercellino I, Rezabkova L, Olieric V, Polyhach Y, Weinert T, Kammerer RA, Jeschke G, Korkhov VM. Role of the nucleotidyl cyclase helical domain in catalytically active dimer formation. Proc Natl Acad Sci U S A 2017; 114:E9821-E9828. [PMID: 29087332 PMCID: PMC5699072 DOI: 10.1073/pnas.1712621114] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
Nucleotidyl cyclases, including membrane-integral and soluble adenylyl and guanylyl cyclases, are central components in a wide range of signaling pathways. These proteins are architecturally diverse, yet many of them share a conserved feature, a helical region that precedes the catalytic cyclase domain. The role of this region in cyclase dimerization has been a subject of debate. Although mutations within this region in various cyclases have been linked to genetic diseases, the molecular details of their effects on the enzymes remain unknown. Here, we report an X-ray structure of the cytosolic portion of the membrane-integral adenylyl cyclase Cya from Mycobacterium intracellulare in a nucleotide-bound state. The helical domains of each Cya monomer form a tight hairpin, bringing the two catalytic domains into an active dimerized state. Mutations in the helical domain of Cya mimic the disease-related mutations in human proteins, recapitulating the profiles of the corresponding mutated enzymes, adenylyl cyclase-5 and retinal guanylyl cyclase-1. Our experiments with full-length Cya and its cytosolic domain link the mutations to protein stability, and the ability to induce an active dimeric conformation of the catalytic domains. Sequence conservation indicates that this domain is an integral part of cyclase machinery across protein families and species. Our study provides evidence for a role of the helical domain in establishing a catalytically competent dimeric cyclase conformation. Our results also suggest that the disease-associated mutations in the corresponding regions of human nucleotidyl cyclases disrupt the normal helical domain structure.
Collapse
Affiliation(s)
- Irene Vercellino
- Laboratory of Biomolecular Research, Division of Biology and Chemistry, Paul Scherrer Institute, 5232 Villigen, Switzerland
| | - Lenka Rezabkova
- Laboratory of Biomolecular Research, Division of Biology and Chemistry, Paul Scherrer Institute, 5232 Villigen, Switzerland
| | - Vincent Olieric
- Macromolecular Crystallography Group, Paul Scherrer Institute, 5232 Villigen, Switzerland
| | - Yevhen Polyhach
- Laboratory of Physical Chemistry, Swiss Federal Institute of Technology in Zurich (ETH Zurich), 8093 Zurich, Switzerland
| | - Tobias Weinert
- Laboratory of Biomolecular Research, Division of Biology and Chemistry, Paul Scherrer Institute, 5232 Villigen, Switzerland
| | - Richard A Kammerer
- Laboratory of Biomolecular Research, Division of Biology and Chemistry, Paul Scherrer Institute, 5232 Villigen, Switzerland
| | - Gunnar Jeschke
- Laboratory of Physical Chemistry, Swiss Federal Institute of Technology in Zurich (ETH Zurich), 8093 Zurich, Switzerland
| | - Volodymyr M Korkhov
- Laboratory of Biomolecular Research, Division of Biology and Chemistry, Paul Scherrer Institute, 5232 Villigen, Switzerland;
- Institute of Biochemistry, ETH Zurich, 8093 Zurich, Switzerland
| |
Collapse
|
18
|
Cyclic AMP-Independent Control of Twitching Motility in Pseudomonas aeruginosa. J Bacteriol 2017; 199:JB.00188-17. [PMID: 28583947 DOI: 10.1128/jb.00188-17] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2017] [Accepted: 05/23/2017] [Indexed: 01/05/2023] Open
Abstract
FimV is a Pseudomonas aeruginosa inner membrane hub protein that modulates levels of the second messenger, cyclic AMP (cAMP), through the activation of adenylate cyclase CyaB. Although type IVa pilus (T4aP)-dependent twitching motility is modulated by cAMP levels, mutants lacking FimV are twitching impaired, even when exogenous cAMP is provided. Here we further define FimV's cAMP-dependent and -independent regulation of twitching. We confirmed that the response regulator of the T4aP-associated Chp chemotaxis system, PilG, requires both FimV and the CyaB regulator, FimL, to activate CyaB. However, in cAMP-replete backgrounds-lacking the cAMP phosphodiesterase CpdA or the CheY-like protein PilH or expressing constitutively active CyaB-pilG and fimV mutants failed to twitch. Both cytoplasmic and periplasmic domains of FimV were important for its cAMP-dependent and -independent roles, while its septal peptidoglycan-targeting LysM motif was required only for twitching motility. Polar localization of the sensor kinase PilS, a key regulator of transcription of the major pilin, was FimV dependent. However, unlike its homologues in other species that localize flagellar system components, FimV was not required for swimming motility. These data provide further evidence to support FimV's role as a key hub protein that coordinates the polar localization and function of multiple structural and regulatory proteins involved in P. aeruginosa twitching motility.IMPORTANCEPseudomonas aeruginosa is a serious opportunistic pathogen. Type IVa pili (T4aP) are important for its virulence, because they mediate dissemination and invasion via twitching motility and are involved in surface sensing, which modulates pathogenicity via changes in cAMP levels. Here we show that the hub protein FimV and the response regulator of the Chp system, PilG, regulate twitching independently of their roles in the modulation of cAMP synthesis. These functions do not require the putative scaffold protein FimL, proposed to link PilG with FimV. PilG may regulate asymmetric functioning of the T4aP system to allow for directional movement, while FimV appears to localize both structural and regulatory elements-including the PilSR two-component system-to cell poles for optimal function.
Collapse
|
19
|
The Conserved Tetratricopeptide Repeat-Containing C-Terminal Domain of Pseudomonas aeruginosa FimV Is Required for Its Cyclic AMP-Dependent and -Independent Functions. J Bacteriol 2016; 198:2263-74. [PMID: 27297880 DOI: 10.1128/jb.00322-16] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2016] [Accepted: 06/06/2016] [Indexed: 01/23/2023] Open
Abstract
UNLABELLED FimV is a Pseudomonas aeruginosa inner membrane protein that regulates intracellular cyclic AMP (cAMP) levels-and thus type IV pilus (T4P)-mediated twitching motility and type II secretion (T2S)-by activating the adenylate cyclase CyaB. Its cytoplasmic domain contains three predicted tetratricopeptide repeat (TPR) motifs separated by an unstructured region: two proximal to the inner membrane and one within the "FimV C-terminal domain," which is highly conserved across diverse homologs. Here, we present the crystal structure of the FimV C terminus, FimV861-919, containing a TPR motif decorated with solvent-exposed, charged side chains, plus a C-terminal capping helix. FimV689, a truncated form lacking this C-terminal motif, did not restore wild-type levels of twitching or surface piliation compared to the full-length protein. FimV689 failed to restore wild-type levels of the T4P motor ATPase PilU or T2S, suggesting that it was unable to activate cAMP synthesis. Bacterial two-hybrid analysis showed that TPR3 interacts directly with the CyaB activator, FimL. However, FimV689 failed to restore wild-type motility in a fimV mutant expressing a constitutively active CyaB (fimV cyaB-R456L), suggesting that the C-terminal motif is also involved in cAMP-independent functions of FimV. The data show that the highly conserved TPR-containing C-terminal domain of FimV is critical for its cAMP-dependent and -independent functions. IMPORTANCE FimV is important for twitching motility and cAMP-dependent virulence gene expression in P. aeruginosa FimV homologs have been identified in several human pathogens, and their functions are not limited to T4P expression. The C terminus of FimV is remarkably conserved among otherwise very diverse family members, but its role is unknown. We provide here biological evidence for the importance of the C-terminal domain in both cAMP-dependent (through FimL) and -independent functions of FimV. We present X-ray crystal structures of the conserved C-terminal domain and identify a consensus sequence for the C-terminal TPR within the conserved domain. Our data extend our knowledge of FimV's functionally important domains, and the structures and consensus sequences provide a foundation for studies of FimV and its homologs.
Collapse
|
20
|
Silversmith RE, Wang B, Fulcher NB, Wolfgang MC, Bourret RB. Phosphoryl Group Flow within the Pseudomonas aeruginosa Pil-Chp Chemosensory System: DIFFERENTIAL FUNCTION OF THE EIGHT PHOSPHOTRANSFERASE AND THREE RECEIVER DOMAINS. J Biol Chem 2016; 291:17677-91. [PMID: 27354279 DOI: 10.1074/jbc.m116.737528] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2016] [Indexed: 11/06/2022] Open
Abstract
Bacterial chemosensory signal transduction systems that regulate motility by type IV pili (T4P) can be markedly more complex than related flagellum-based chemotaxis systems. In T4P-based systems, the CheA kinase often contains numerous potential sites of phosphorylation, but the signaling mechanisms of these systems are unknown. In Pseudomonas aeruginosa, the Pil-Chp system regulates T4P-mediated twitching motility and cAMP levels, both of which play roles in pathogenesis. The Pil-Chp histidine kinase (ChpA) has eight "Xpt" domains; six are canonical histidine-containing phosphotransfer (Hpt) domains and two have a threonine (Tpt) or serine (Spt) in place of the histidine. Additionally, there are two stand-alone receiver domains (PilG and PilH) and a ChpA C-terminal receiver domain (ChpArec). Here, we demonstrate that the ChpA Xpts are functionally divided into three categories as follows: (i) those phosphorylated with ATP (Hpt4-6); (ii) those reversibly phosphorylated by ChpArec (Hpt2-6), and (iii) those with no detectable phosphorylation (Hpt1, Spt, and Tpt). There was rapid phosphotransfer from Hpt2-6 to ChpArec and from Hpt3 to PilH, whereas transfer to PilG was slower. ChpArec also had a rapid rate of autodephosphorylation. The biochemical results together with in vivo cAMP and twitching phenotypes of key ChpA phosphorylation site point mutants supported a scheme whereby ChpArec functions both as a phosphate sink and a phosphotransfer element linking Hpt4-6 to Hpt2-3. Hpt2 and Hpt3 are likely the dominant sources of phosphoryl groups for PilG and PilH, respectively. The data are synthesized in a signaling circuit that contains fundamental features of two-component phosphorelays.
Collapse
Affiliation(s)
| | - Boya Wang
- Cystic Fibrosis/Pulmonary Research and Treatment Center, University of North Carolina, Chapel Hill, North Carolina 27599
| | - Nanette B Fulcher
- Cystic Fibrosis/Pulmonary Research and Treatment Center, University of North Carolina, Chapel Hill, North Carolina 27599
| | - Matthew C Wolfgang
- From the Department of Microbiology and Immunology and Cystic Fibrosis/Pulmonary Research and Treatment Center, University of North Carolina, Chapel Hill, North Carolina 27599
| | | |
Collapse
|
21
|
Jansari VH, Potharla VY, Riddell GT, Bardy SL. Twitching motility and cAMP levels: signal transduction through a single methyl-accepting chemotaxis protein. FEMS Microbiol Lett 2016; 363:fnw119. [PMID: 27190147 DOI: 10.1093/femsle/fnw119] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/29/2016] [Indexed: 12/17/2022] Open
Abstract
The Pseudomonas aeruginosa Chp chemosensory system regulates twitching motility, intracellular adenosine 3('') 5(')-cyclic monophosphate (cAMP) levels and is postulated to be involved in directional twitching towards phosphatidylethanolamine (PE). Because PilJ is the only methyl-accepting chemotaxis protein (MCP) identified in the Chp system, we determined the role of PilJ in mediating signal transduction for the distinct outputs of this system. Mutants that lack the periplasmic domain of PilJ (pilJΔ74-273) showed lower levels of cAMP but retained directional twitching towards PE. While initial studies revealed reduced twitching motility by PilJΔ74-273, this was due to decreased cAMP levels. Our data illustrate the importance of the periplasmic domain of PilJ in regulating cAMP. This is the first time a defined domain within PilJ has been identified as having a distinct role in signal transduction.
Collapse
Affiliation(s)
- Vibhuti H Jansari
- Department of Biological Sciences, University of Wisconsin-Milwaukee, Milwaukee, WI 53211, USA
| | - Vishwakanth Y Potharla
- Department of Biological Sciences, University of Wisconsin-Milwaukee, Milwaukee, WI 53211, USA
| | - Geoff T Riddell
- Department of Biological Sciences, University of Wisconsin-Milwaukee, Milwaukee, WI 53211, USA
| | - Sonia L Bardy
- Department of Biological Sciences, University of Wisconsin-Milwaukee, Milwaukee, WI 53211, USA
| |
Collapse
|
22
|
Phosphoenolpyruvate Phosphotransferase System Components Modulate Gene Transcription and Virulence of Borrelia burgdorferi. Infect Immun 2015; 84:754-64. [PMID: 26712207 DOI: 10.1128/iai.00917-15] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2015] [Accepted: 12/17/2015] [Indexed: 12/16/2022] Open
Abstract
The phosphoenolpyruvate phosphotransferase system (PEP-PTS) and adenylate cyclase (AC) IV (encoded by BB0723 [cyaB]) are well conserved in different species of Borrelia. However, the functional roles of PEP-PTS and AC in the infectious cycle of Borrelia have not been characterized previously. We examined 12 PEP-PTS transporter component mutants by needle inoculation of mice to assess their ability to cause mouse infection. Transposon mutants with mutations in the EIIBC components (ptsG) (BB0645, thought to be involved in glucose-specific transport) were unable to cause infection in mice, while all other tested PEP-PTS mutants retained infectivity. Infectivity was partially restored in an in trans-complemented strain of the ptsG mutant. While the ptsG mutant survived normally in unfed as well as fed ticks, it was unable to cause infection in mice by tick transmission, suggesting that the function of ptsG is essential to establish infection by either needle inoculation or tick transmission. In Gram-negative organisms, the regulatory effects of the PEP-PTS are mediated by adenylate cyclase and cyclic AMP (cAMP) levels. A recombinant protein encoded by B. burgdorferi BB0723 (a putative cyaB homolog) was shown to have adenylate cyclase activity in vitro; however, mutants with mutations in this gene were fully infectious in the tick-mouse infection cycle, indicating that its function is not required in this process. By transcriptome analysis, we demonstrated that the ptsG gene may directly or indirectly modulate gene expression of Borrelia burgdorferi. Overall, the PEP-PTS glucose transporter PtsG appears to play important roles in the pathogenesis of B. burgdorferi that extend beyond its transport functions.
Collapse
|
23
|
The Cyclic AMP-Vfr Signaling Pathway in Pseudomonas aeruginosa Is Inhibited by Cyclic Di-GMP. J Bacteriol 2015; 197:2190-200. [PMID: 25897033 DOI: 10.1128/jb.00193-15] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2015] [Accepted: 04/16/2015] [Indexed: 11/20/2022] Open
Abstract
UNLABELLED The opportunistic human pathogen Pseudomonas aeruginosa expresses numerous acute virulence factors in the initial phase of infection, and during long-term colonization it undergoes adaptations that optimize survival in the human host. Adaptive changes that often occur during chronic infection give rise to rugose small colony variants (RSCVs), which are hyper-biofilm-forming mutants that commonly possess mutations that increase production of the biofilm-promoting secondary messenger cyclic di-GMP (c-di-GMP). We show that RSCVs display a decreased production of acute virulence factors as a direct result of elevated c-di-GMP content. Overproduction of c-di-GMP causes a decrease in the transcription of virulence factor genes that are regulated by the global virulence regulator Vfr. The low level of Vfr-dependent transcription is caused by a low level of its coactivator, cyclic AMP (cAMP), which is decreased in response to a high level of c-di-GMP. Mutations that cause reversion of the RSCV phenotype concomitantly reactivate Vfr-cAMP signaling. Attempts to uncover the mechanism underlying the observed c-di-GMP-mediated lowering of cAMP content provided evidence that it is not caused by inhibition of adenylate cyclase production or activity and that it is not caused by activation of cAMP phosphodiesterase activity. In addition to the studies of the RSCVs, we present evidence that the deeper layers of wild-type P. aeruginosa biofilms have high c-di-GMP levels and low cAMP levels. IMPORTANCE Our work suggests that cross talk between c-di-GMP and cAMP signaling pathways results in downregulation of acute virulence factors in P. aeruginosa biofilm infections. Knowledge about this cross-regulation adds to our understanding of virulence traits and immune evasion by P. aeruginosa in chronic infections and may provide new approaches to eradicate biofilm infections.
Collapse
|
24
|
Affiliation(s)
- Lonny R. Levin
- Department of Pharmacology, Weill Cornell Medical College, New York, NY 10065; ,
| | - Jochen Buck
- Department of Pharmacology, Weill Cornell Medical College, New York, NY 10065; ,
| |
Collapse
|
25
|
Wang J. On the validation of crystallographic symmetry and the quality of structures. Protein Sci 2014; 24:621-32. [PMID: 25352397 DOI: 10.1002/pro.2595] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2014] [Revised: 10/20/2014] [Accepted: 10/24/2014] [Indexed: 11/06/2022]
Abstract
In 2008, Zwart and colleagues observed that the fraction of the structures deposited in the PDB alleged to have "pseudosymmetry" or "special noncrystallographic symmetry" (NCS) was about 6%, and that this percentage was rising annually. A few years later, Poon and colleagues found that 2% of all the crystal structures in the PDB belonged to higher symmetry space groups than those assigned to them. Here, I report an analysis of the X-ray diffraction data deposited for this class of structures, which shows that most of the "pseudosymmetry" and "special NCS" that has been reported is in fact true crystallographic symmetry (CS). This distinction is important because the credibility of crystal structures depends heavily on quality control statistics such as Rfree that are unreliable when they are computed incorrectly, which they often are when CS is misidentified as "special NCS" or "pseudosymmetry". When mistakes of this kind are made, artificially low values of Rfree can give unjustified confidence in the accuracy of the reported structures.
Collapse
Affiliation(s)
- Jimin Wang
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut, 06520
| |
Collapse
|
26
|
Steegborn C. Structure, mechanism, and regulation of soluble adenylyl cyclases — similarities and differences to transmembrane adenylyl cyclases. Biochim Biophys Acta Mol Basis Dis 2014; 1842:2535-47. [DOI: 10.1016/j.bbadis.2014.08.012] [Citation(s) in RCA: 142] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2014] [Revised: 08/19/2014] [Accepted: 08/26/2014] [Indexed: 12/14/2022]
|
27
|
Barathy D, Mattoo R, Visweswariah S, Suguna K. New structural forms of a mycobacterial adenylyl cyclase Rv1625c. IUCRJ 2014; 1:338-48. [PMID: 25295175 PMCID: PMC4174876 DOI: 10.1107/s2052252514016741] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/19/2014] [Accepted: 07/19/2014] [Indexed: 06/03/2023]
Abstract
Rv1625c is one of 16 adenylyl cyclases encoded in the genome of Mycobacterium tuberculosis. In solution Rv1625c exists predominantly as a monomer, with a small amount of dimer. It has been shown previously that the monomer is active and the dimeric fraction is inactive. Both fractions of wild-type Rv1625c crystallized as head-to-head inactive domain-swapped dimers as opposed to the head-to-tail dimer seen in other functional adenylyl cyclases. About half of the molecule is involved in extensive domain swapping. The strain created by a serine residue located on a hinge loop and the crystallization condition might have led to this unusual domain swapping. The inactivity of the dimeric form of Rv1625c could be explained by the absence of the required catalytic site in the swapped dimer. A single mutant of the enzyme was also generated by changing a phenylalanine predicted to occur at the functional dimer interface to an arginine. This single mutant exists as a dimer in solution but crystallized as a monomer. Analysis of the structure showed that a salt bridge formed between a glutamate residue in the N-terminal segment and the mutated arginine residue hinders dimer formation by pulling the N-terminal region towards the dimer interface. Both structures reported here show a change in the dimerization-arm region which is involved in formation of the functional dimer. It is concluded that the dimerization arm along with other structural elements such as the N-terminal region and certain loops are vital for determining the oligomeric nature of the enzyme, which in turn dictates its activity.
Collapse
Affiliation(s)
- Deivanayaga Barathy
- Molecular Biophysics Unit, Indian Institute of Science, C. V. Raman Avenue, Bangalore, Karnataka 560 012, India
| | - Rohini Mattoo
- Molecular Reproduction, Development and Genetics, Indian Institute of Science, C. V. Raman Avenue, Bangalore, Karnataka 560 012, India
| | - Sandhya Visweswariah
- Molecular Reproduction, Development and Genetics, Indian Institute of Science, C. V. Raman Avenue, Bangalore, Karnataka 560 012, India
| | - Kaza Suguna
- Molecular Biophysics Unit, Indian Institute of Science, C. V. Raman Avenue, Bangalore, Karnataka 560 012, India
| |
Collapse
|
28
|
Kleinboelting S, van den Heuvel J, Steegborn C. Structural analysis of human soluble adenylyl cyclase and crystal structures of its nucleotide complexes-implications for cyclase catalysis and evolution. FEBS J 2014; 281:4151-64. [PMID: 25040695 DOI: 10.1111/febs.12913] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2014] [Revised: 06/29/2014] [Accepted: 07/04/2014] [Indexed: 01/18/2023]
Abstract
UNLABELLED The ubiquitous second messenger cAMP regulates a wide array of functions, from bacterial transcription to mammalian memory. It is synthesized by six evolutionarily distinct adenylyl cyclase (AC) families. In mammals, there are two AC types: nine transmembrane ACs (tmACs) and one soluble AC (sAC). Both AC types belong to the widespread cyclase class III, which has members in numerous organisms from archaeons to mammals. Class III also contains all known guanylyl cyclases (GCs), which synthesize the cAMP-related messenger cGMP in many eukaryotes and possibly some prokaryotes. Among mammalian ACs, sAC is uniquely regulated by bicarbonate, and has been proposed to be more closely related to a bacterial AC subfamily than to mammalian ACs, on the basis of sequence comparisons. Here, we used crystal structures of human sAC catalytic domains to analyze its relationships with other class III ACs and GCs, and to study its substrate selection mechanisms. Structural comparisons revealed a similarity within an sAC-like subfamily but no family-specific structure elements, and an unexpected sAC similarity to eukaryotic GCs and a potential bacterial GC. We further solved novel crystal structures of sAC catalytic domains in complex with a substrate analog, unprocessed ATP substrate, and product after soaking with ATP or GTP. The structures show a novel ATP-binding conformation, and suggest mechanisms for substrate association and recognition. Our results could explain the limited substrate specificity of sAC, suggest how specificity is increased in other cyclases, and indicate evolutionary relationships among class III enzymes, with sAC being close to a putative 'ancestor' cyclase. DATABASE Coordinates and structure factors for the novel sAC-cat structures described have been deposited with the Worldwide PDB (www.pdb.org): ApCpp soak (entry 4usu), ATP + Ca(2+) soak (entry 4usv), GTP + Mg(2+) soak (entry 4ust), ATP soak (entry 4usw).
Collapse
|
29
|
Biochemical and functional characterization of SpdA, a 2', 3'cyclic nucleotide phosphodiesterase from Sinorhizobium meliloti. BMC Microbiol 2013; 13:268. [PMID: 24279347 PMCID: PMC4222275 DOI: 10.1186/1471-2180-13-268] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2013] [Accepted: 11/11/2013] [Indexed: 01/10/2023] Open
Abstract
Background 3′, 5′cAMP signaling in Sinorhizobium meliloti was recently shown to contribute to the autoregulation of legume infection. In planta, three adenylate cyclases CyaD1, CyaD2 and CyaK, synthesizing 3′, 5′cAMP, together with the Crp-like transcriptional regulator Clr and smc02178, a gene of unknown function, are involved in controlling plant infection. Results Here we report on the characterization of a gene (smc02179, spdA) at the cyaD1 locus that we predicted to encode a class III cytoplasmic phosphodiesterase. First, we have shown that spdA had a similar pattern of expression as smc02178 in planta but did not require clr nor 3′, 5′cAMP for expression. Second, biochemical characterization of the purified SpdA protein showed that, contrary to expectation, it had no detectable activity against 3′, 5′cAMP and, instead, high activity against the positional isomers 2′, 3′cAMP and 2′, 3′cGMP. Third, we provide direct experimental evidence that the purified Clr protein was able to bind both 2′, 3′cAMP and 3′, 5′cAMP in vitro at high concentration. We further showed that Clr is a 3′, 5′cAMP-dependent DNA-binding protein and identified a DNA-binding motif to which Clr binds. In contrast, 2′, 3′cAMP was unable to promote Clr specific-binding to DNA and activate smc02178 target gene expression ex planta. Fourth, we have shown a negative impact of exogenous 2′, 3′cAMP on 3′, 5′cAMP-mediated signaling in vivo. A spdA null mutant was also partially affected in 3′, 5′cAMP signaling. Conclusions SpdA is a nodule-expressed 2′, 3′ specific phosphodiesterase whose biological function remains elusive. Circumstantial evidence suggests that SpdA may contribute insulating 3′, 5′cAMP-based signaling from 2′, 3′ cyclic nucleotides of metabolic origin.
Collapse
|
30
|
Obiako B, Calchary W, Xu N, Kunstadt R, Richardson B, Nix J, Sayner SL. Bicarbonate disruption of the pulmonary endothelial barrier via activation of endogenous soluble adenylyl cyclase, isoform 10. Am J Physiol Lung Cell Mol Physiol 2013; 305:L185-92. [PMID: 23686854 PMCID: PMC3726949 DOI: 10.1152/ajplung.00392.2012] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2012] [Accepted: 05/14/2013] [Indexed: 01/23/2023] Open
Abstract
It is becoming increasingly apparent that cAMP signals within the pulmonary endothelium are highly compartmentalized, and this compartmentalization is critical to maintaining endothelial barrier integrity. Studies demonstrate that the exogenous soluble bacterial toxin, ExoY, and heterologous expression of the forskolin-stimulated soluble mammalian adenylyl cyclase (AC) chimera, sACI/II, elevate cytosolic cAMP and disrupt the pulmonary microvascular endothelial barrier. The barrier-disruptive effects of cytosolic cAMP generated by exogenous soluble ACs are in contrast to the barrier-protective effects of subplasma membrane cAMP generated by transmembrane AC, which strengthens endothelial barrier integrity. Endogenous soluble AC isoform 10 (AC10 or commonly known as sAC) lacks transmembrane domains and localizes within the cytosolic compartment. AC10 is uniquely activated by bicarbonate to generate cytosolic cAMP, yet its role in regulation of endothelial barrier integrity has not been addressed. Here we demonstrate that, within the pulmonary circulation, AC10 is expressed in pulmonary microvascular endothelial cells (PMVECs) and pulmonary artery endothelial cells (PAECs), yet expression in PAECs is lower. Furthermore, pulmonary endothelial cells selectively express bicarbonate cotransporters. While extracellular bicarbonate generates a phosphodiesterase 4-sensitive cAMP pool in PMVECs, no such cAMP response is detected in PAECs. Finally, addition of extracellular bicarbonate decreases resistance across the PMVEC monolayer and increases the filtration coefficient in the isolated perfused lung above osmolality controls. Collectively, these findings suggest that PMVECs have a bicarbonate-sensitive cytosolic cAMP pool that disrupts endothelial barrier integrity. These studies could provide an alternative mechanism for the controversial effects of bicarbonate correction of acidosis of acute respiratory distress syndrome patients.
Collapse
Affiliation(s)
- Boniface Obiako
- Department of Cell Biology and Neuroscience, University of South Alabama, Mobile, AL 36688, USA
| | | | | | | | | | | | | |
Collapse
|
31
|
Abstract
The second messengers cAMP and cGMP mediate a multitude of physiological processes. In mammals, these cyclic nucleotides are formed by related Class III nucleotidyl cyclases, and both ACs (adenylate cyclases) and GCs (guanylate cyclases) comprise transmembrane receptors as well as soluble isoforms. Whereas sGC (soluble GC) has a well-characterized regulatory HD (haem domain) that acts as a receptor for the activator NO (nitric oxide), very little is known about the regulatory domains of the ubiquitous signalling enzyme sAC (soluble AC). In the present study, we identify a unique type of HD as a regulatory domain in sAC. The sAC-HD (sAC haem domain) forms a larger oligomer and binds, non-covalently, one haem cofactor per monomer. Spectral analyses and mutagenesis reveal a 6-fold co-ordinated haem iron atom, probably with non-typical axial ligands, which can bind both NO and CO (carbon monoxide). Splice variants of sAC comprising this domain are expressed in testis and skeletal muscle, and the HD displays an activating effect on the sAC catalytic core. Our results reveal a novel mechanism for regulation of cAMP signalling and suggest a need for reanalysis of previous studies on mechanisms of haem ligand effects on cyclic nucleotide signalling, particularly in testis and skeletal muscle.
Collapse
|
32
|
Gancedo JM. Biological roles of cAMP: variations on a theme in the different kingdoms of life. Biol Rev Camb Philos Soc 2013; 88:645-68. [PMID: 23356492 DOI: 10.1111/brv.12020] [Citation(s) in RCA: 119] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2012] [Revised: 12/19/2012] [Accepted: 12/20/2012] [Indexed: 12/18/2022]
Abstract
Cyclic AMP (cAMP) plays a key regulatory role in most types of cells; however, the pathways controlled by cAMP may present important differences between organisms and between tissues within a specific organism. Changes in cAMP levels are caused by multiple triggers, most affecting adenylyl cyclases, the enzymes that synthesize cAMP. Adenylyl cyclases form a large and diverse family including soluble forms and others with one or more transmembrane domains. Regulatory mechanisms for the soluble adenylyl cyclases involve either interaction with diverse proteins, as happens in Escherichia coli or yeasts, or with calcium or bicarbonate ions, as occurs in mammalian cells. The transmembrane cyclases can be regulated by a variety of proteins, among which the α subunit and the βγ complex from G proteins coupled to membrane receptors are prominent. cAMP levels also are controlled by the activity of phosphodiesterases, enzymes that hydrolyze cAMP. Phosphodiesterases can be regulated by cAMP, cGMP or calcium-calmodulin or by phosphorylation by different protein kinases. Regulation through cAMP depends on its binding to diverse proteins, its proximal targets, this in turn causing changes in a variety of distal targets. Specifically, binding of cAMP to regulatory subunits of cAMP-dependent protein kinases (PKAs) affects the activity of substrates of PKA, binding to exchange proteins directly activated by cAMP (Epac) regulates small GTPases, binding to transcription factors such as the cAMP receptor protein (CRP) or the virulence factor regulator (Vfr) modifies the rate of transcription of certain genes, while cAMP binding to ion channels modulates their activity directly. Further studies on cAMP signalling will have important implications, not only for advancing fundamental knowledge but also for identifying targets for the development of new therapeutic agents.
Collapse
Affiliation(s)
- Juana M Gancedo
- Department of Metabolism and Cell Signalling, Instituto de Investigaciones Biomédicas Alberto Sols CSIC-UAM, Madrid 28029, Spain.
| |
Collapse
|
33
|
Soluble adenylyl cyclase activity is necessary for retinal ganglion cell survival and axon growth. J Neurosci 2012; 32:7734-44. [PMID: 22649251 DOI: 10.1523/jneurosci.5288-11.2012] [Citation(s) in RCA: 72] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
cAMP is a critical second messenger mediating activity-dependent neuronal survival and neurite growth. We investigated the expression and function of the soluble adenylyl cyclase (sAC, ADCY10) in CNS retinal ganglion cells (RGCs). We found sAC protein expressed in multiple RGC compartments including the nucleus, cytoplasm and axons. sAC activation increased cAMP above the level seen with transmembrane adenylate cyclase (tmAC) activation. Electrical activity and bicarbonate, both physiologic sAC activators, significantly increased survival and axon growth, whereas pharmacologic or siRNA-mediated sAC inhibition dramatically decreased RGC survival and axon growth in vitro, and survival in vivo. Conversely, RGC survival and axon growth were unaltered in RGCs from AC1/AC8 double knock-out mice or after specifically inhibiting tmACs. These data identify a novel sAC-mediated cAMP signaling pathway regulating RGC survival and axon growth, and suggest new neuroprotective or regenerative strategies based on sAC modulation.
Collapse
|