1
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Cerna‐Vargas JP, Krell T. Exploring solute binding proteins in Pseudomonas aeruginosa that bind to γ-aminobutyrate and 5-aminovalerate and their role in activating sensor kinases. Microbiologyopen 2024; 13:e1415. [PMID: 38780167 PMCID: PMC11113362 DOI: 10.1002/mbo3.1415] [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: 04/08/2024] [Revised: 05/09/2024] [Accepted: 05/13/2024] [Indexed: 05/25/2024] Open
Abstract
The standard method of receptor activation involves the binding of signals or signal-loaded solute binding proteins (SBPs) to sensor domains. Many sensor histidine kinases (SHKs), which are activated by SBP binding, are encoded adjacent to their corresponding sbp gene. We examined three SBPs of Pseudomonas aeruginosa PAO1, encoded near the genes for the AgtS (PA0600) and AruS (PA4982) SHKs, to determine how common this arrangement is. Ligand screening and microcalorimetric studies revealed that the SBPs PA0602 and PA4985 preferentially bind to GABA (KD = 2.3 and 0.58 μM, respectively), followed by 5-aminovalerate (KD = 30 and 1.6 μM, respectively) and ethanoldiamine (KD = 2.3 and 0.58 μM, respectively). In contrast, AgtB (PA0604) exclusively recognizes 5-aminovaleric acid (KD = 2.9 μM). However, microcalorimetric titrations did not show any binding between the AgtS sensor domain and AgtB or PA0602, regardless of the presence of ligands. Similarly, bacterial two-hybrid assays did not demonstrate an interaction between PA4985 and the AruS sensor domain. Therefore, sbp and shk genes located nearby are not always functionally linked. We previously identified PA0222 as a GABA-specific SBP. The presence of three SBPs for GABA may be linked to GABA's role as a trigger for P. aeruginosa virulence.
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Affiliation(s)
- Jean Paul Cerna‐Vargas
- Department of Biotechnology and Environmental Protection, Estación Experimental del ZaidínConsejo Superior de Investigaciones CientíficasGranadaSpain
- Centro de Biotecnología y Genómica de Plantas, Universidad Politécnica de Madrid Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria/Consejo Superior de Investigaciones CientíficasParque Científico y Tecnológico de la Universidad Politécnica de Madrid, Pozuelo de AlarcónMadridSpain
| | - Tino Krell
- Department of Biotechnology and Environmental Protection, Estación Experimental del ZaidínConsejo Superior de Investigaciones CientíficasGranadaSpain
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2
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Blachier F. Amino Acid-Derived Bacterial Metabolites in the Colorectal Luminal Fluid: Effects on Microbial Communication, Metabolism, Physiology, and Growth. Microorganisms 2023; 11:1317. [PMID: 37317289 DOI: 10.3390/microorganisms11051317] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2023] [Revised: 05/14/2023] [Accepted: 05/15/2023] [Indexed: 06/16/2023] Open
Abstract
Undigested dietary and endogenous proteins, as well as unabsorbed amino acids, can move from the terminal part of the ileum into the large intestine, where they meet a dense microbial population. Exfoliated cells and mucus released from the large intestine epithelium also supply nitrogenous material to this microbial population. The bacteria in the large intestine luminal fluid release amino acids from the available proteins, and amino acids are then used for bacterial protein synthesis, energy production, and in other various catabolic pathways. The resulting metabolic intermediaries and end products can then accumulate in the colorectal fluid, and their concentrations appear to depend on different parameters, including microbiota composition and metabolic activity, substrate availability, and the capacity of absorptive colonocytes to absorb these metabolites. The aim of the present review is to present how amino acid-derived bacterial metabolites can affect microbial communication between both commensal and pathogenic microorganisms, as well as their metabolism, physiology, and growth.
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Affiliation(s)
- François Blachier
- Université Paris-Saclay, AgroParisTech, INRAe, UMR PNCA, 91120 Palaiseau, France
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3
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Chen D, Cadelis MM, Rouvier F, Troia T, Edmeades LR, Fraser K, Gill ES, Bourguet-Kondracki ML, Brunel JM, Copp BR. α,ω-Diacyl-Substituted Analogues of Natural and Unnatural Polyamines: Identification of Potent Bactericides That Selectively Target Bacterial Membranes. Int J Mol Sci 2023; 24:5882. [PMID: 36982955 PMCID: PMC10052977 DOI: 10.3390/ijms24065882] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2023] [Revised: 03/14/2023] [Accepted: 03/19/2023] [Indexed: 03/30/2023] Open
Abstract
In this study, α-ω-disubstituted polyamines exhibit a range of potentially useful biological activities, including antimicrobial and antibiotic potentiation properties. We have prepared an expanded set of diarylbis(thioureido)polyamines that vary in central polyamine core length, identifying analogues with potent methicillin-resistant Staphylococcus aureus (MRSA), Escherichia coli, Acinetobacter baumannii and Candida albicans growth inhibition properties, in addition to the ability to enhance action of doxycycline towards Gram-negative bacterium Pseudomonas aeruginosa. The observation of associated cytotoxicity/hemolytic properties prompted synthesis of an alternative series of diacylpolyamines that explored aromatic head groups of varying lipophilicity. Examples bearing terminal groups each containing two phenyl rings (15a-f, 16a-f) were found to have optimal intrinsic antimicrobial properties, with MRSA being the most susceptible organism. A lack of observed cytotoxicity or hemolytic properties for all but the longest polyamine chain variants identified these as non-toxic Gram-positive antimicrobials worthy of further study. Analogues bearing either one or three aromatic-ring-containing head groups were either generally devoid of antimicrobial properties (one ring) or cytotoxic/hemolytic (three rings), defining a rather narrow range of head group lipophilicity that affords selectivity for Gram-positive bacterial membranes versus mammalian. Analogue 15d is bactericidal and targets the Gram-positive bacterial membrane.
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Affiliation(s)
- Dan Chen
- School of Chemical Sciences, The University of Auckland, Private Bag 92019, Auckland 1142, New Zealand
| | - Melissa M. Cadelis
- School of Chemical Sciences, The University of Auckland, Private Bag 92019, Auckland 1142, New Zealand
| | - Florent Rouvier
- UMR MD1 “Membranes et Cibles Therapeutiques”, U1261 INSERM, Faculté de Pharmacie, Aix-Marseille Universite, 27 bd Jean Moulin, 13385 Marseille, France
| | - Thomas Troia
- UMR MD1 “Membranes et Cibles Therapeutiques”, U1261 INSERM, Faculté de Pharmacie, Aix-Marseille Universite, 27 bd Jean Moulin, 13385 Marseille, France
| | - Liam R. Edmeades
- School of Chemical Sciences, The University of Auckland, Private Bag 92019, Auckland 1142, New Zealand
| | - Kyle Fraser
- School of Chemical Sciences, The University of Auckland, Private Bag 92019, Auckland 1142, New Zealand
| | - Evangelene S. Gill
- School of Chemical Sciences, The University of Auckland, Private Bag 92019, Auckland 1142, New Zealand
| | - Marie-Lise Bourguet-Kondracki
- Laboratoire Molécules de Communication et Adaptation des Micro-Organismes, UMR 7245 CNRS, Muséum National d’Histoire Naturelle, 57 Rue Cuvier (C.P. 54), 75005 Paris, France
| | - Jean Michel Brunel
- UMR MD1 “Membranes et Cibles Therapeutiques”, U1261 INSERM, Faculté de Pharmacie, Aix-Marseille Universite, 27 bd Jean Moulin, 13385 Marseille, France
| | - Brent R. Copp
- School of Chemical Sciences, The University of Auckland, Private Bag 92019, Auckland 1142, New Zealand
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Chávez-Jacobo VM, Becerra-Rivera VA, Guerrero G, Dunn MF. The Sinorhizobium meliloti NspS-MbaA system affects biofilm formation, exopolysaccharide production and motility in response to specific polyamines. MICROBIOLOGY (READING, ENGLAND) 2023; 169:001293. [PMID: 36748569 PMCID: PMC9993111 DOI: 10.1099/mic.0.001293] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
We previously showed that specific polyamines (PAs) present in the extracellular environment markedly affect extracellular polysaccharide (EPS) production, biofilm formation and motility in Sinorhizobium meliloti Rm8530. We hypothesized that extracellular PA signals were sensed and transduced by the NspS and MbaA proteins, respectively, which are homologs of the PA-sensing, c-di-GMP modulating NspS-MbaA proteins described in Vibrio cholerae. Here we show that the decrease in biofilm formation and EPS production in the quorum-sensing (QS)-deficient S. meliloti wild-type strain 1021 in cultures containing putrescine or spermine did not occur in a 1021 nspS mutant (1021 nspS). The transcriptional expression of nspS in strain 1021 was significantly increased in cultures containing either of these polyamines, but not by exogenous cadaverine, 1,3-diaminopropane (DAP), spermidine (Spd) or norspermidine (NSpd). Cell aggregation in liquid cultures did not differ markedly between strain 1021 and 1021 nspS in the presence or absence of PAs. The S. meliloti QS-proficient Rm8530 wild-type and nspS mutant (Rm8530 nspS) produced similar levels of biofilm under control conditions and 3.2- and 2.2-fold more biofilm, respectively, in cultures with NSpd, but these changes did not correlate with EPS production. Cells of Rm8530 nspS aggregated from two- to several-fold more than the wild-type in cultures without PAs or in those containing Spm. NSpd, Spd and DAP differently affected swimming and swarming motility in strains 1021 and Rm8530 and their respective nspS mutants. nspS transcription in strain Rm8530 was greatly reduced by exogenous Spm. Bioinformatic analysis revealed similar secondary structures and functional domains in the MbaA proteins of S. meliloti and V. cholerae, while their NspS proteins differed in some residues implicated in polyamine recognition in the latter species. NspS-MbaA homologs occur in a small subset of soil and aquatic bacterial species that commonly interact with eukaryotes. We speculate that the S. meliloti NspS-MbaA system modulates biofilm formation, EPS production and motility in response to environmental or host plant-produced PAs.
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Affiliation(s)
- Víctor M Chávez-Jacobo
- Programa en Genómica Funcional de Procariotes, Universidad Nacional Autónoma de México, Cuernavaca, Morelos, 62210, Mexico
| | - Víctor A Becerra-Rivera
- Programa en Genómica Funcional de Procariotes, Universidad Nacional Autónoma de México, Cuernavaca, Morelos, 62210, Mexico
| | - Gabriela Guerrero
- Unidad de Análisis Bioinformáticos, Centro de Ciencias Genómicas, Universidad Nacional Autónoma de México, Cuernavaca, Morelos, 62210, Mexico
| | - Michael F Dunn
- Programa en Genómica Funcional de Procariotes, Universidad Nacional Autónoma de México, Cuernavaca, Morelos, 62210, Mexico
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Tai JSB, Ferrell MJ, Yan J, Waters CM. New Insights into Vibrio cholerae Biofilms from Molecular Biophysics to Microbial Ecology. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2023; 1404:17-39. [PMID: 36792869 PMCID: PMC10726288 DOI: 10.1007/978-3-031-22997-8_2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/17/2023]
Abstract
With the discovery that 48% of cholera infections in rural Bangladesh villages could be prevented by simple filtration of unpurified waters and the detection of Vibrio cholerae aggregates in stools from cholera patients it was realized V. cholerae biofilms had a central function in cholera pathogenesis. We are currently in the seventh cholera pandemic, caused by O1 serotypes of the El Tor biotypes strains, which initiated in 1961. It is estimated that V. cholerae annually causes millions of infections and over 100,000 deaths. Given the continued emergence of cholera in areas that lack access to clean water, such as Haiti after the 2010 earthquake or the ongoing Yemen civil war, increasing our understanding of cholera disease remains a worldwide public health priority. The surveillance and treatment of cholera is also affected as the world is impacted by the COVID-19 pandemic, raising significant concerns in Africa. In addition to the importance of biofilm formation in its life cycle, V. cholerae has become a key model system for understanding bacterial signal transduction networks that regulate biofilm formation and discovering fundamental principles about bacterial surface attachment and biofilm maturation. This chapter will highlight recent insights into V. cholerae biofilms including their structure, ecological role in environmental survival and infection, regulatory systems that control them, and biomechanical insights into the nature of V. cholerae biofilms.
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Affiliation(s)
- Jung-Shen B Tai
- Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, CT, USA
| | - Micah J Ferrell
- Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, MI, USA
| | - Jing Yan
- Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, CT, USA
| | - Christopher M Waters
- Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, MI, USA.
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6
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Matilla MA, Monteagudo-Cascales E, Krell T. Advances in the identification of signals and novel sensing mechanisms for signal transduction systems. Environ Microbiol 2023; 25:79-86. [PMID: 35896893 DOI: 10.1111/1462-2920.16142] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2022] [Accepted: 07/16/2022] [Indexed: 01/21/2023]
Affiliation(s)
- Miguel A Matilla
- Department of Environmental Protection, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas, Granada, Spain
| | - Elizabet Monteagudo-Cascales
- Department of Environmental Protection, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas, Granada, Spain
| | - Tino Krell
- Department of Environmental Protection, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas, Granada, Spain
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7
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Ortega Á, Matilla MA, Krell T. The Repertoire of Solute-Binding Proteins of Model Bacteria Reveals Large Differences in Number, Type, and Ligand Range. Microbiol Spectr 2022; 10:e0205422. [PMID: 36121253 PMCID: PMC9602780 DOI: 10.1128/spectrum.02054-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2022] [Accepted: 08/24/2022] [Indexed: 12/31/2022] Open
Abstract
Solute-binding proteins (SBPs) are of central physiological relevance for bacteria. They are located in the extracytosolic space, where they present substrates to transporters but also stimulate different types of transmembrane receptors coordinating compound uptake with signal transduction. SBPs are a superfamily composed of proteins recognized by 45 Pfam profiles. The definition of SBP profiles for bacteria is hampered by the fact that these Pfam profiles recognize sensor domains for different types of signaling proteins or cytosolic proteins with alternative functions. We report here the retrieval of the SBPs from 49 bacterial model strains with different lifestyles and phylogenetic distributions. Proteins were manually curated, and the ligands recognized were predicted bioinformatically. There were very large differences in the number and type of SBPs between strains, ranging from 7 SBPs in Helicobacter pylori 26695 to 189 SBPs in Sinorhizobium meliloti 1021. SBPs were found to represent 0.22 to 5.13% of the total protein-encoding genes. The abundance of SBPs was largely determined by strain phylogeny, and no obvious link with the bacterial lifestyle was noted. Most abundant (36%) were SBPs predicted to recognize amino acids or peptides, followed by those expected to bind different sugars (18%). To the best of our knowledge, this is the first comparative study of bacterial SBP repertoires. Given the importance of SBPs in nutrient uptake and signaling, this study enhances the knowledge of model bacteria and will permit the definition of SBP profiles of other strains. IMPORTANCE SBPs are essential components for many transporters, but multiple pieces of more recent evidence indicate that the SBP-mediated stimulation of different transmembrane receptors is a general and widespread signal transduction mechanism in bacteria. The double function of SBPs in coordinating transport with signal transduction remains to a large degree unexplored and represents a major research need. The definition of the SBP repertoire of the 49 bacterial model strains examined here, along with information on their cognate ligand profiles forms the basis to close this gap in knowledge. Furthermore, this study provides information on the forces that have driven the evolution of transporters with different ligand specificities in bacteria that differ in phylogenetics and lifestyle. This article is also a first step in setting up automatic algorithms that permit the large-scale identification of the SBP repertoire in proteomes.
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Affiliation(s)
- Álvaro Ortega
- Department of Biochemistry and Molecular Biology B and Immunology, Faculty of Chemistry, University of Murcia, Regional Campus of International Excellence Campus Mare Nostrum, Murcia, Spain
| | - Miguel A. Matilla
- Department of Environmental Protection, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas, Granada, Spain
| | - Tino Krell
- Department of Environmental Protection, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas, Granada, Spain
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8
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Alkhzem AH, Laabei M, Woodman TJ, Blagbrough IS. Practical Synthesis of Polyamine Succinamides and Branched Polyamines. Chemistry 2022; 11:e202200147. [PMID: 36284254 PMCID: PMC9596609 DOI: 10.1002/open.202200147] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2022] [Revised: 08/09/2022] [Indexed: 11/22/2022]
Abstract
Antibiotic resistance is now a growing threat to human health, further exacerbated by the lack of new antibiotics. We describe the practical synthesis of a series of substituted polyamine succinamides and branched polyamines that are potential new antibiotics against both Gram‐positive and Gram‐negative bacteria, including MRSA and Pseudomonas aeruginosa. They are prepared via 1,4‐Michael addition of acrylonitrile and then hydrogenation of the nitrile functional groups to primary amines. They are built upon the framework of the naturally occurring polyamines thermine (3.3.3, norspermine) and spermine (3.4.3), homo‐ and heterodimeric polyamine succinic amides. Linking two of the same or different polyamines together via amide bonds can be achieved by introducing a carboxylic acid group on the first polyamine, then coupling that released carboxylic acid to a free primary amine in the second polyamine. If the addition of positive charges on the amino groups along the polyamine chains are a key factor in their antimicrobial activity against Gram‐negative bacteria, then increasing them will increase the antimicrobial activity. Synthesising polyamine amide dimers will increase the total net positive charge compared to their monomers. The design and practical synthesis of such homo‐ and hetero‐dimers of linear polyamines, spermine and norspermine, are reported. Several of these compounds do not display significant antibacterial activity against Gram‐positive or Gram‐negative bacteria, including MRSA and Pseudomonas aeruginosa. However, the most charged analogue, a branched polyamine carrying eight positive charges at physiological pH, displays antibiofilm activity with a 50 % reduction in PAO1 at 16–32 μg mL−1.
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Affiliation(s)
- Abdulaziz H. Alkhzem
- Department of Pharmacy and PharmacologyUniversity of BathClaverton DownBathBA2 7AYUK
| | - Maisem Laabei
- Department of Biology and BiochemistryUniversity of BathClaverton DownBathBA2 7AYUK
| | - Timothy J. Woodman
- Department of Pharmacy and PharmacologyUniversity of BathClaverton DownBathBA2 7AYUK
| | - Ian S. Blagbrough
- Department of Pharmacy and PharmacologyUniversity of BathClaverton DownBathBA2 7AYUK
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9
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Bridges AA, Prentice JA, Wingreen NS, Bassler BL. Signal Transduction Network Principles Underlying Bacterial Collective Behaviors. Annu Rev Microbiol 2022; 76:235-257. [PMID: 35609948 PMCID: PMC9463083 DOI: 10.1146/annurev-micro-042922-122020] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Bacteria orchestrate collective behaviors and accomplish feats that would be unsuccessful if carried out by a lone bacterium. Processes undertaken by groups of bacteria include bioluminescence, biofilm formation, virulence factor production, and release of public goods that are shared by the community. Collective behaviors are controlled by signal transduction networks that integrate sensory information and transduce the information internally. Here, we discuss network features and mechanisms that, even in the face of dramatically changing environments, drive precise execution of bacterial group behaviors. We focus on representative quorum-sensing and second-messenger cyclic dimeric GMP (c-di-GMP) signal relays. We highlight ligand specificity versus sensitivity, how small-molecule ligands drive discrimination of kin versus nonkin, signal integration mechanisms, single-input sensory systems versus coincidence detectors, and tuning of input-output dynamics via feedback regulation. We summarize how different features of signal transduction systems allow groups of bacteria to successfully interpret and collectively react to dynamically changing environments.
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Affiliation(s)
- Andrew A Bridges
- Department of Molecular Biology, Princeton University, Princeton, New Jersey, USA; , , ,
| | - Jojo A Prentice
- Department of Molecular Biology, Princeton University, Princeton, New Jersey, USA; , , ,
| | - Ned S Wingreen
- Department of Molecular Biology, Princeton University, Princeton, New Jersey, USA; , , ,
- Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, New Jersey, USA
| | - Bonnie L Bassler
- Department of Molecular Biology, Princeton University, Princeton, New Jersey, USA; , , ,
- Howard Hughes Medical Institute, Chevy Chase, Maryland, USA
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10
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Teschler JK, Nadell CD, Drescher K, Yildiz FH. Mechanisms Underlying Vibrio cholerae Biofilm Formation and Dispersion. Annu Rev Microbiol 2022; 76:503-532. [PMID: 35671532 DOI: 10.1146/annurev-micro-111021-053553] [Citation(s) in RCA: 23] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Biofilms are a widely observed growth mode in which microbial communities are spatially structured and embedded in a polymeric extracellular matrix. Here, we focus on the model bacterium Vibrio cholerae and summarize the current understanding of biofilm formation, including initial attachment, matrix components, community dynamics, social interactions, molecular regulation, and dispersal. The regulatory network that orchestrates the decision to form and disperse from biofilms coordinates various environmental inputs. These cues are integrated by several transcription factors, regulatory RNAs, and second-messenger molecules, including bis-(3'-5')-cyclic dimeric guanosine monophosphate (c-di-GMP). Through complex mechanisms, V. cholerae weighs the energetic cost of forming biofilms against the benefits of protection and social interaction that biofilms provide. Expected final online publication date for the Annual Review of Microbiology, Volume 76 is September 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.
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Affiliation(s)
- Jennifer K Teschler
- Department of Microbiology and Environmental Toxicology, University of California, Santa Cruz, California, USA;
| | - Carey D Nadell
- Department of Biological Sciences, Dartmouth College, Hanover, New Hampshire, USA
| | | | - Fitnat H Yildiz
- Department of Microbiology and Environmental Toxicology, University of California, Santa Cruz, California, USA;
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11
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Bridges AA, Prentice JA, Fei C, Wingreen NS, Bassler BL. Quantitative input-output dynamics of a c-di-GMP signal transduction cascade in Vibrio cholerae. PLoS Biol 2022; 20:e3001585. [PMID: 35302986 PMCID: PMC8967002 DOI: 10.1371/journal.pbio.3001585] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2021] [Revised: 03/30/2022] [Accepted: 02/25/2022] [Indexed: 12/13/2022] Open
Abstract
Bacterial biofilms are multicellular communities that collectively overcome environmental threats and clinical treatments. To regulate the biofilm lifecycle, bacteria commonly transduce sensory information via the second messenger molecule cyclic diguanylate (c-di-GMP). Using experimental and modeling approaches, we quantitatively capture c-di-GMP signal transmission via the bifunctional polyamine receptor NspS-MbaA, from ligand binding to output, in the pathogen Vibrio cholerae. Upon binding of norspermidine or spermidine, NspS-MbaA synthesizes or degrades c-di-GMP, respectively, which, in turn, drives alterations specifically to biofilm gene expression. A long-standing question is how output specificity is achieved via c-di-GMP, a diffusible molecule that regulates dozens of effectors. We show that NspS-MbaA signals locally to specific effectors, sensitizing V. cholerae to polyamines. However, local signaling is not required for specificity, as changes to global cytoplasmic c-di-GMP levels can selectively regulate biofilm genes. This work establishes the input-output dynamics underlying c-di-GMP signaling, which could be useful for developing bacterial manipulation strategies.
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Affiliation(s)
- Andrew A. Bridges
- Department of Molecular Biology, Princeton University, Princeton, New Jersey, United States of America
| | - Jojo A. Prentice
- Department of Molecular Biology, Princeton University, Princeton, New Jersey, United States of America
| | - Chenyi Fei
- Department of Molecular Biology, Princeton University, Princeton, New Jersey, United States of America
- Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, New Jersey, United States of America
| | - Ned S. Wingreen
- Department of Molecular Biology, Princeton University, Princeton, New Jersey, United States of America
- Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, New Jersey, United States of America
- * E-mail: (NSW); (BLB)
| | - Bonnie L. Bassler
- Department of Molecular Biology, Princeton University, Princeton, New Jersey, United States of America
- The Howard Hughes Medical Institute, Chevy Chase, Maryland, United States of America
- * E-mail: (NSW); (BLB)
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12
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Putrescine and its metabolic precursor arginine promote biofilm and c-di-GMP synthesis in Pseudomonas aeruginosa. J Bacteriol 2021; 204:e0029721. [PMID: 34723645 DOI: 10.1128/jb.00297-21] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Pseudomonas aeruginosa, an opportunistic bacterial pathogen can synthesize and catabolize a number of small cationic molecules known as polyamines. In several clades of bacteria polyamines regulate biofilm formation, a lifestyle-switching process that confers resistance to environmental stress. The polyamine putrescine and its biosynthetic precursors, L-arginine and agmatine, promote biofilm formation in Pseudomonas spp. However, it remains unclear whether the effect is a direct effect of polyamines or through a metabolic derivative. Here we used a genetic approach to demonstrate that putrescine accumulation, either through disruption of the spermidine biosynthesis pathway or the catabolic putrescine aminotransferase pathway, promoted biofilm formation in P. aeruginosa. Consistent with this observation, exogenous putrescine robustly induced biofilm formation in P. aeruginosa that was dependent on putrescine uptake and biosynthesis pathways. Additionally, we show that L-arginine, the biosynthetic precursor of putrescine, also promoted biofilm formation, but via a mechanism independent of putrescine or agmatine conversion. We found that both putrescine and L-arginine induced a significant increase in the intracellular level of bis-(3'-5')-cyclic dimeric guanosine monophosphate (c-di-GMP) (c-di-GMP), a bacterial second messenger widely found in Proteobacteria that upregulates biofilm formation. Collectively these data show that putrescine and its metabolic precursor arginine promote biofilm and c-di-GMP synthesis in P. aeruginosa. Importance: Biofilm formation allows bacteria to physically attach to a surface, confers tolerance to antimicrobial agents, and promotes resistance to host immune responses. As a result, regulation of biofilm is often crucial for bacterial pathogens to establish chronic infections. A primary mechanism of biofilm promotion in bacteria is the molecule c-di-GMP, which promotes biofilm formation. The level of c-di-GMP is tightly regulated by bacterial enzymes. In this study, we found that putrescine, a small molecule ubiquitously found in eukaryotic cells, robustly enhances P. aeruginosa biofilm and c-di-GMP. We propose that P. aeruginosa may sense putrescine as a host-associated signal that triggers a lifestyle switching that favors chronic infection.
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13
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Short FL, Liu Q, Shah B, Clift HE, Naidu V, Li L, Prity FT, Mabbutt BC, Hassan KA, Paulsen IT. The Acinetobacter baumannii disinfectant resistance protein, AmvA, is a spermidine and spermine efflux pump. Commun Biol 2021; 4:1114. [PMID: 34552198 PMCID: PMC8458285 DOI: 10.1038/s42003-021-02629-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2020] [Accepted: 09/01/2021] [Indexed: 02/08/2023] Open
Abstract
Antimicrobial resistance genes, including multidrug efflux pumps, evolved long before the ubiquitous use of antimicrobials in medicine and infection control. Multidrug efflux pumps often transport metabolites, signals and host-derived molecules in addition to antibiotics or biocides. Understanding their ancestral physiological roles could inform the development of strategies to subvert their activity. In this study, we investigated the response of Acinetobacter baumannii to polyamines, a widespread, abundant class of amino acid-derived metabolites, which led us to identify long-chain polyamines as natural substrates of the disinfectant efflux pump AmvA. Loss of amvA dramatically reduced tolerance to long-chain polyamines, and these molecules induce expression of amvA through binding to its cognate regulator AmvR. A second clinically-important efflux pump, AdeABC, also contributed to polyamine tolerance. Our results suggest that the disinfectant resistance capability that allows A. baumannii to survive in hospitals may have evolutionary origins in the transport of polyamine metabolites.
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Affiliation(s)
- Francesca L. Short
- grid.1004.50000 0001 2158 5405Department of Molecular Sciences, Macquarie University, North Ryde, NSW Australia ,grid.1002.30000 0004 1936 7857Department of Microbiology, Biomedicine Discovery Institute, Monash University, Clayton, VIC Australia
| | - Qi Liu
- grid.1004.50000 0001 2158 5405Department of Molecular Sciences, Macquarie University, North Ryde, NSW Australia
| | - Bhumika Shah
- grid.1004.50000 0001 2158 5405Department of Molecular Sciences, Macquarie University, North Ryde, NSW Australia
| | - Heather E. Clift
- grid.1004.50000 0001 2158 5405Department of Molecular Sciences, Macquarie University, North Ryde, NSW Australia ,grid.280427.b0000 0004 0434 015XPresent Address: Versiti Blood Research Institute, Milwaukee, WI USA
| | - Varsha Naidu
- grid.1004.50000 0001 2158 5405Department of Molecular Sciences, Macquarie University, North Ryde, NSW Australia
| | - Liping Li
- grid.1004.50000 0001 2158 5405Department of Molecular Sciences, Macquarie University, North Ryde, NSW Australia
| | - Farzana T. Prity
- grid.1004.50000 0001 2158 5405Department of Molecular Sciences, Macquarie University, North Ryde, NSW Australia
| | - Bridget C. Mabbutt
- grid.1004.50000 0001 2158 5405Department of Molecular Sciences, Macquarie University, North Ryde, NSW Australia
| | - Karl A. Hassan
- grid.266842.c0000 0000 8831 109XSchool of Environmental and Life Sciences, University of Newcastle, Callaghan, NSW Australia
| | - Ian T. Paulsen
- grid.1004.50000 0001 2158 5405Department of Molecular Sciences, Macquarie University, North Ryde, NSW Australia
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Vibrio cholerae Infection Induces Strain-Specific Modulation of the Zebrafish Intestinal Microbiome. Infect Immun 2021; 89:e0015721. [PMID: 34061623 DOI: 10.1128/iai.00157-21] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Zebrafish (Danio rerio) is an attractive model organism to use for an array of scientific studies, including host-microbe interactions. Zebrafish contain a core (i.e., consistently detected) intestinal microbiome consisting primarily of Proteobacteria. Furthermore, this core intestinal microbiome is plastic and can be significantly altered due to external factors. Zebrafish are particularly useful for the study of aquatic microbes that can colonize vertebrate hosts, including Vibrio cholerae. As an intestinal pathogen, V. cholerae must colonize the intestine of an exposed host for pathogenicity to occur. Members of the resident intestinal microbial community likely must be reduced or eliminated by V. cholerae for colonization, and subsequent disease, to occur. Many studies have explored a variety of aspects of the pathogenic effects of V. cholerae on zebrafish and other model organisms but few have researched how a V. cholerae infection changes the resident intestinal microbiome. In this study, 16S rRNA gene sequencing was used to examine how five genetically diverse V. cholerae strains alter the intestinal microbiome following an infection. We found that V. cholerae colonization induced significant changes in the zebrafish intestinal microbiome. Notably, changes in the microbial profile were significantly different from each other, based on the particular strain of V. cholerae used to infect zebrafish hosts. We conclude that V. cholerae significantly modulates the zebrafish intestinal microbiota to enable colonization and that specific microbes that are targeted depend on the V. cholerae genotype.
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The Vibrio cholerae Type Six Secretion System Is Dispensable for Colonization but Affects Pathogenesis and the Structure of Zebrafish Intestinal Microbiome. Infect Immun 2021; 89:e0015121. [PMID: 34097462 DOI: 10.1128/iai.00151-21] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Zebrafish (Danio rerio) are an attractive model organism for a variety of scientific studies, including host-microbe interactions. The organism is particularly useful for the study of aquatic microbes that can colonize vertebrate hosts, including Vibrio cholerae, an intestinal pathogen. V. cholerae must colonize the intestine of an exposed host for pathogenicity to occur. While numerous studies have explored various aspects of the pathogenic effects of V. cholerae on zebrafish and other model organisms, few, if any, have examined how a V. cholerae infection alters the resident intestinal microbiome and the role of the type six secretion system (T6SS) in that process. In this study, 16S rRNA gene sequencing was utilized to investigate how strains of V. cholerae both with and without the T6SS alter the aforementioned microbial profiles following an infection. V. cholerae infection induced significant changes in the zebrafish intestinal microbiome, and while not necessary for colonization, the T6SS was important for inducing mucin secretion, a marker for diarrhea. Additional salient differences to the microbiome were observed based on the presence or absence of the T6SS in the V. cholerae utilized for challenging the zebrafish hosts. We conclude that V. cholerae significantly modulates the zebrafish intestinal microbiome to enable colonization and that the T6SS is important for pathogenesis induced by the examined V. cholerae strains. Furthermore, the presence or absence of T6SS differentially and significantly affected the composition and structure of the intestinal microbiome, with an increased abundance of other Vibrio bacteria observed in the absence of V. cholerae T6SS.
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16
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Niu C, Zhang S, Mo G, Jiang Y, Li L, Xu H, Han C, Zhao H, Yan Y, Hu S, Hu J, Kang B, Jiang D. Effects of ODC on polyamine metabolism, hormone levels, cell proliferation and apoptosis in goose ovarian granulosa cells. Poult Sci 2021; 100:101226. [PMID: 34175802 PMCID: PMC8254008 DOI: 10.1016/j.psj.2021.101226] [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: 10/13/2020] [Revised: 04/13/2021] [Accepted: 04/14/2021] [Indexed: 11/16/2022] Open
Abstract
Ornithine decarboxylase (ODC) plays an indispensable role in the process of polyamine biosynthesis. Polyamines are a pivotal part of living cells and have diverse roles in the regulation of cell proliferation and apoptosis, aging and reproduction. However, to date, there have been no reports about ODC regulating follicular development in goose ovaries. Here, we constructed ODC siRNA and overexpression plasmids and transfected them into goose primary granulosa cells (GCs) to elucidate the effects of ODC interference and overexpression on the polyamine metabolism, hormone levels, cell apoptosis and proliferation of granulosa cells. After interfering with ODC in GCs, the mRNA and protein levels of ODC and the content of putrescine were greatly decreased (P < 0.05). When ODC was overexpressed, ODC mRNA and protein levels and putrescine content were greatly increased (P < 0.05). The polyamine-metabolizing enzyme genes ornithine decarboxylase antizyme 1 (OAZ1) and spermidine / spermine-N1-acetyltransferase (SSAT) were significantly increased, and spermidine synthase (SPDS) was significantly decreased when ODC was downregulated (P < 0.05). OAZ1, SPDS and SSAT were significantly increased when ODC was upregulated (P < 0.05). In addition, after interference with ODC, progesterone (P4) levels in the culture medium of GCs increased greatly (P < 0.05), while the overexpression of ODC caused the P4 level to decrease significantly (P < 0.05). After ODC downregulation, granulosa cell activity was significantly reduced, the apoptosis rate was significantly increased, and the BCL-2 / BAX ratio was downregulated (P < 0.05). Under ODC overexpression, the activity of GCs was notably increased, the apoptosis rate was significantly reduced, and the BCL-2 / BAX protein ratio was upregulated (P < 0.05). Our study successfully induced ODC interference and overexpression in goose ovarian GCs, and ODC regulated mainly putrescine content in GCs with a slight influence on spermidine and spermine. Moreover, ODC participated in the adjustment of P4 levels in the culture medium of GCs, promoted granulosa cell proliferation and inhibited granulosa cell apoptosis.
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Affiliation(s)
- Chunyang Niu
- College of Animal Science and Technology, Sichuan Agricultural University, Chengdu 611130, P. R. China
| | - Sujuan Zhang
- College of Animal Science and Technology, Sichuan Agricultural University, Chengdu 611130, P. R. China
| | - Guilin Mo
- College of Animal Science and Technology, Sichuan Agricultural University, Chengdu 611130, P. R. China
| | - Yilong Jiang
- College of Animal Science and Technology, Sichuan Agricultural University, Chengdu 611130, P. R. China
| | - Liang Li
- College of Animal Science and Technology, Sichuan Agricultural University, Chengdu 611130, P. R. China
| | - Hengyong Xu
- College of Animal Science and Technology, Sichuan Agricultural University, Chengdu 611130, P. R. China
| | - Chunchun Han
- College of Animal Science and Technology, Sichuan Agricultural University, Chengdu 611130, P. R. China
| | - Hua Zhao
- Animal Nutrition Institute, Sichuan Agricultural University, Chengdu, P. R. China
| | - Yanhong Yan
- College of Animal Science and Technology, Sichuan Agricultural University, Chengdu 611130, P. R. China
| | - Shenqiang Hu
- College of Animal Science and Technology, Sichuan Agricultural University, Chengdu 611130, P. R. China
| | - Jiwei Hu
- College of Animal Science and Technology, Sichuan Agricultural University, Chengdu 611130, P. R. China
| | - Bo Kang
- College of Animal Science and Technology, Sichuan Agricultural University, Chengdu 611130, P. R. China
| | - Dongmei Jiang
- College of Animal Science and Technology, Sichuan Agricultural University, Chengdu 611130, P. R. China.
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17
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Bridges AA, Bassler BL. Inverse regulation of Vibrio cholerae biofilm dispersal by polyamine signals. eLife 2021; 10:65487. [PMID: 33856344 PMCID: PMC8079147 DOI: 10.7554/elife.65487] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2020] [Accepted: 04/13/2021] [Indexed: 12/12/2022] Open
Abstract
The global pathogen Vibrio cholerae undergoes cycles of biofilm formation and dispersal in the environment and the human host. Little is understood about biofilm dispersal. Here, we show that MbaA, a periplasmic polyamine sensor, and PotD1, a polyamine importer, regulate V. cholerae biofilm dispersal. Spermidine, a commonly produced polyamine, drives V. cholerae dispersal, whereas norspermidine, an uncommon polyamine produced by vibrios, inhibits dispersal. Spermidine and norspermidine differ by one methylene group. Both polyamines control dispersal via MbaA detection in the periplasm and subsequent signal relay. Our results suggest that dispersal fails in the absence of PotD1 because endogenously produced norspermidine is not reimported, periplasmic norspermidine accumulates, and it stimulates MbaA signaling. These results suggest that V. cholerae uses MbaA to monitor environmental polyamines, blends of which potentially provide information about numbers of ‘self’ and ‘other’. This information is used to dictate whether or not to disperse from biofilms.
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Affiliation(s)
- Andrew A Bridges
- Department of Molecular Biology, Princeton University, Princeton, United States.,The Howard Hughes Medical Institute, Chevy Chase, United States
| | - Bonnie L Bassler
- Department of Molecular Biology, Princeton University, Princeton, United States.,The Howard Hughes Medical Institute, Chevy Chase, United States
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18
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Le VTB, Tsimbalyuk S, Lim EQ, Solis A, Gawat D, Boeck P, Lim EQ, Renolo R, Forwood JK, Kuhn ML. The Vibrio cholerae SpeG Spermidine/Spermine N-Acetyltransferase Allosteric Loop and β6-β7 Structural Elements Are Critical for Kinetic Activity. Front Mol Biosci 2021; 8:645768. [PMID: 33928120 PMCID: PMC8076852 DOI: 10.3389/fmolb.2021.645768] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2020] [Accepted: 02/16/2021] [Indexed: 11/27/2022] Open
Abstract
Polyamines regulate many important biological processes including gene expression, intracellular signaling, and biofilm formation. Their intracellular concentrations are tightly regulated by polyamine transport systems and biosynthetic and catabolic pathways. Spermidine/spermine N-acetyltransferases (SSATs) are catabolic enzymes that acetylate polyamines and are critical for maintaining intracellular polyamine homeostasis. These enzymes belong to the Gcn5-related N-acetyltransferase (GNAT) superfamily and adopt a highly conserved fold found across all kingdoms of life. SpeG is an SSAT protein found in a variety of bacteria, including the human pathogen Vibrio cholerae. This protein adopts a dodecameric structure and contains an allosteric site, making it unique compared to other SSATs. Currently, we have a limited understanding of the critical structural components of this protein that are required for its allosteric behavior. Therefore, we explored the importance of two key regions of the SpeG protein on its kinetic activity. To achieve this, we created various constructs of the V. cholerae SpeG protein, including point mutations, a deletion, and chimeras with residues from the structurally distinct and non-allosteric human SSAT protein. We measured enzyme kinetic activity toward spermine for ten constructs and crystallized six of them. Ultimately, we identified specific portions of the allosteric loop and the β6-β7 structural elements that were critical for enzyme kinetic activity. These results provide a framework for further study of the structure/function relationship of SpeG enzymes from other organisms and clues toward the structural evolution of members of the GNAT family across domains of life.
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Affiliation(s)
- Van Thi Bich Le
- Department of Chemistry & Biochemistry, San Francisco State University, San Francisco, CA, United States
| | - Sofiya Tsimbalyuk
- School of Biomedical Science, Charles Sturt University, Wagga Wagga, NSW, Australia
| | - Ee Qi Lim
- Department of Chemistry & Biochemistry, San Francisco State University, San Francisco, CA, United States
| | - Allan Solis
- Department of Chemistry & Biochemistry, San Francisco State University, San Francisco, CA, United States
| | - Darwin Gawat
- Department of Chemistry & Biochemistry, San Francisco State University, San Francisco, CA, United States
| | - Paloma Boeck
- Department of Chemistry & Biochemistry, San Francisco State University, San Francisco, CA, United States
| | - Ee Qing Lim
- Department of Chemistry & Biochemistry, San Francisco State University, San Francisco, CA, United States
| | - Rosselini Renolo
- Department of Chemistry & Biochemistry, San Francisco State University, San Francisco, CA, United States
| | - Jade K. Forwood
- School of Biomedical Science, Charles Sturt University, Wagga Wagga, NSW, Australia
| | - Misty L. Kuhn
- Department of Chemistry & Biochemistry, San Francisco State University, San Francisco, CA, United States
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19
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Matilla MA, Ortega Á, Krell T. The role of solute binding proteins in signal transduction. Comput Struct Biotechnol J 2021; 19:1786-1805. [PMID: 33897981 PMCID: PMC8050422 DOI: 10.1016/j.csbj.2021.03.029] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2021] [Revised: 03/22/2021] [Accepted: 03/22/2021] [Indexed: 12/13/2022] Open
Abstract
The solute binding proteins (SBPs) of prokaryotes are present in the extracytosolic space. Although their primary function is providing substrates to transporters, SBPs also stimulate different signaling proteins, including chemoreceptors, sensor kinases, diguanylate cyclases/phosphodiesterases and Ser/Thr kinases, thereby causing a wide range of responses. While relatively few such systems have been identified, several pieces of evidence suggest that SBP-mediated receptor activation is a widespread mechanism. (1) These systems have been identified in Gram-positive and Gram-negative bacteria and archaea. (2) There is a structural diversity in the receptor domains that bind SBPs. (3) SBPs belonging to thirteen different families interact with receptor ligand binding domains (LBDs). (4) For the two most abundant receptor LBD families, dCache and four-helix-bundle, there are different modes of interaction with SBPs. (5) SBP-stimulated receptors carry out many different functions. The advantage of SBP-mediated receptor stimulation is attributed to a strict control of SBP levels, which allows a precise adjustment of the systeḿs sensitivity. We have compiled information on the effect of ligands on the transcript/protein levels of their cognate SBPs. In 87 % of the cases analysed, ligands altered SBP expression levels. The nature of the regulatory effect depended on the ligand family. Whereas inorganic ligands typically downregulate SBP expression, an upregulation was observed in response to most sugars and organic acids. A major unknown is the role that SBPs play in signaling and in receptor stimulation. This review attempts to summarize what is known and to present new information to narrow this gap in knowledge.
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Affiliation(s)
- Miguel A Matilla
- Department of Environmental Protection, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas, Prof. Albareda 1, Granada 18008, Spain
| | - Álvaro Ortega
- Department of Biochemistry and Molecular Biology 'B' and Immunology, Faculty of Chemistry, University of Murcia, Regional Campus of International Excellence "Campus Mare Nostrum", Murcia, Spain
| | - Tino Krell
- Department of Environmental Protection, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas, Prof. Albareda 1, Granada 18008, Spain
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20
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Yoon SH, Waters CM. The ever-expanding world of bacterial cyclic oligonucleotide second messengers. Curr Opin Microbiol 2021; 60:96-103. [PMID: 33640793 DOI: 10.1016/j.mib.2021.01.017] [Citation(s) in RCA: 29] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2020] [Revised: 01/27/2021] [Accepted: 01/30/2021] [Indexed: 01/08/2023]
Abstract
Cyclic dinucleotide (cdN) second messengers are essential for bacteria to sense and adapt to their environment. These signals were first discovered with the identification of 3'-5', 3'-5' cyclic di-GMP (c-di-GMP) in 1987, a second messenger that is now known to be the linchpin signaling pathway modulating bacterial motility and biofilm formation. In the past 15 years, three more cdNs were uncovered: 3'-5', 3'-5' cyclic di-AMP (c-di-AMP) and 3'-5', 3'-5' cyclic GMP-AMP (3',3' cGAMP) in bacteria and 2'-5', 3'-5' cyclic GMP-AMP (2',3' cGAMP) in eukaryotes. We now appreciate that bacteria can synthesize many varieties of cdNs from every ribonucleotide, and even cyclic trinucleotide (ctN) second messengers have been discovered. Here we highlight our current understanding of c-di-GMP and c-di-AMP in bacterial physiology and focus on recent advances in 3',3' cGAMP signaling effectors, its role in bacterial phage response, and the diversity of its synthase family.
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Affiliation(s)
- Soo Hun Yoon
- Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, MI, 48824 USA
| | - Christopher M Waters
- Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, MI, 48824 USA.
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21
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Young EC, Baumgartner JT, Karatan E, Kuhn ML. A mutagenic screen reveals NspS residues important for regulation of Vibrio cholerae biofilm formation. MICROBIOLOGY-SGM 2021; 167. [PMID: 33502310 DOI: 10.1099/mic.0.001023] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Biofilm formation in the human intestinal pathogen Vibrio cholerae is in part regulated by norspermidine, spermidine and spermine. V. cholerae senses these polyamines through a signalling pathway consisting of the periplasmic protein, NspS, and the integral membrane c-di-GMP phosphodiesterase MbaA. NspS and MbaA belong to a proposed class of novel signalling systems composed of periplasmic ligand-binding proteins and membrane-bound c-di-GMP phosphodiesterases containing both GGDEF and EAL domains. In this signal transduction pathway, NspS is hypothesized to interact with MbaA in the periplasm to regulate its phosphodiesterase activity. Polyamine binding to NspS likely alters this interaction, leading to the activation or inhibition of biofilm formation depending on the polyamine. The purpose of this study was to determine the amino acids important for NspS function. We performed random mutagenesis of the nspS gene, identified mutant clones deficient in biofilm formation, determined their responsiveness to norspermidine and mapped the location of these residues onto NspS homology models. Single mutants clustered on two lobes of the NspS model, but the majority were found on a single lobe that appeared to be more mobile upon norspermidine binding. We also identified residues in the putative ligand-binding site that may be important for norspermidine binding and interactions with MbaA. Ultimately, our results provide new insights into this novel signalling pathway in V. cholerae and highlight differences between periplasmic binding proteins involved in transport versus signal transduction.
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Affiliation(s)
- Erin C Young
- Department of Biology, Appalachian State University, Boone, NC, USA
| | - Jackson T Baumgartner
- Department of Chemistry and Biochemistry, San Francisco State University, San Francisco, CA, USA
| | - Ece Karatan
- Department of Biology, Appalachian State University, Boone, NC, USA
| | - Misty L Kuhn
- Department of Chemistry and Biochemistry, San Francisco State University, San Francisco, CA, USA
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22
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Liu Y, Feng H, Chen L, Zhang H, Dong X, Xiong Q, Zhang R. Root-Secreted Spermine Binds to Bacillus amyloliquefaciens SQR9 Histidine Kinase KinD and Modulates Biofilm Formation. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2020; 33:423-432. [PMID: 31741422 DOI: 10.1094/mpmi-07-19-0201-r] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
The signal molecules in root exudates that are sensed by plant growth-promoting rhizobacteria (PGPR) are critical to regulate their root colonization. Phosphorylated Spo0A is an important global transcriptional regulator that controls colonization and sporulation in Bacillus species. In this study, we found that deletion of kinD from PGPR strain Bacillus amyloliquefaciens SQR9, encoding an original phosphate donor of Spo0A, resulted in reduced biofilm formation in root exudates compared with the wild-type strain, indicating that KinD is responsible for sensing root exudates. Ligands of B. amyloliquefaciens SQR9 KinD in cucumber root exudates were determined by both the nontargeted ligand fishing method and the targeted surface plasmon resonance detection method. In total, we screened 80 compounds in root exudates for binding to KinD and found that spermine and guanosine could bind to KinD with dissociation constant values of 213 and 51 μΜ, respectively. In addition, calcium l-threonate, N-acetyl-l-aspartic acid, sodium decanoic acid, and parabanic acid could also bind weakly to KinD. The three-dimensional binding models were then constructed to demonstrate the interactions between the root-secreted signals and KinD. It was observed that exogenous spermine reduced the wrinkles of biofilm when kinD was deleted, indicating that KinD might be involved in sensing root-secreted spermine and stabilizing biofilm in response to this negative effector. This study provided a new insight of interaction between a rhizobacterial sensor and root-secreted signals.
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Affiliation(s)
- Yunpeng Liu
- Key Laboratory of Microbial Resources Collection and Preservation, Ministry of Agriculture, Institute of Agricultural Resources and Regional Planning, Chinese Academy of Agricultural Sciences, Beijing, 100081, P.R. China
| | - Haichao Feng
- Jiangsu Key Lab and Engineering Center for Solid Organic Waste Utilization, National Engineering Research Center for Organic-based Fertilizers, Nanjing Agricultural University, Nanjing, 210095, P.R. China
| | - Lin Chen
- Experimental Center of Forestry in North China, Chinese Academy of Forestry, Beijing, 102300, P. R. China
| | - Huihui Zhang
- Jiangsu Key Lab and Engineering Center for Solid Organic Waste Utilization, National Engineering Research Center for Organic-based Fertilizers, Nanjing Agricultural University, Nanjing, 210095, P.R. China
| | - Xiaoyan Dong
- Jiangsu Key Lab and Engineering Center for Solid Organic Waste Utilization, National Engineering Research Center for Organic-based Fertilizers, Nanjing Agricultural University, Nanjing, 210095, P.R. China
| | - Qin Xiong
- Key Laboratory of Microbial Resources Collection and Preservation, Ministry of Agriculture, Institute of Agricultural Resources and Regional Planning, Chinese Academy of Agricultural Sciences, Beijing, 100081, P.R. China
| | - Ruifu Zhang
- Key Laboratory of Microbial Resources Collection and Preservation, Ministry of Agriculture, Institute of Agricultural Resources and Regional Planning, Chinese Academy of Agricultural Sciences, Beijing, 100081, P.R. China
- Jiangsu Key Lab and Engineering Center for Solid Organic Waste Utilization, National Engineering Research Center for Organic-based Fertilizers, Nanjing Agricultural University, Nanjing, 210095, P.R. China
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23
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Rinaldo S, Giardina G, Mantoni F, Paone A, Cutruzzolà F. Beyond nitrogen metabolism: nitric oxide, cyclic-di-GMP and bacterial biofilms. FEMS Microbiol Lett 2019; 365:4834012. [PMID: 29401255 DOI: 10.1093/femsle/fny029] [Citation(s) in RCA: 43] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2017] [Accepted: 01/31/2018] [Indexed: 12/18/2022] Open
Abstract
The nitrogen cycle pathways are responsible for the circulation of inorganic and organic N-containing molecules in nature. Among these pathways, those involving amino acids, N-oxides and in particular nitric oxide (NO) play strategic roles in the metabolism of microorganisms in natural environments and in host-pathogen interactions. Beyond their role in the N-cycle, amino acids and NO are also signalling molecules able to influence group behaviour in microorganisms and cell-cell communication in multicellular organisms, including humans. In this minireview, we summarise the role of these compounds in the homeostasis of the bacterial communities called biofilms, commonly found in environmental, industrial and medical settings. Biofilms are difficult to eradicate since they are highly resistant to antimicrobials and to the host immune system. We highlight the effect of amino acids such as glutamate, glutamine and arginine and of NO on the signalling pathways involved in the metabolism of 3',5'-cyclic diguanylic acid (c-di-GMP), a master regulator of motility, attachment and group behaviour in bacteria. The study of the metabolic routes involving these N-containing compounds represents an attractive topic to identify targets for biofilm control in both natural and medical settings.
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Affiliation(s)
- Serena Rinaldo
- Department of Biochemical Sciences, Istituto Pasteur Italia-Fondazione Cenci Bolognetti, Sapienza University of Rome, 00185 Rome, Italy
| | - Giorgio Giardina
- Department of Biochemical Sciences, Istituto Pasteur Italia-Fondazione Cenci Bolognetti, Sapienza University of Rome, 00185 Rome, Italy
| | - Federico Mantoni
- Department of Biochemical Sciences, Istituto Pasteur Italia-Fondazione Cenci Bolognetti, Sapienza University of Rome, 00185 Rome, Italy
| | - Alessio Paone
- Department of Biochemical Sciences, Istituto Pasteur Italia-Fondazione Cenci Bolognetti, Sapienza University of Rome, 00185 Rome, Italy
| | - Francesca Cutruzzolà
- Department of Biochemical Sciences, Istituto Pasteur Italia-Fondazione Cenci Bolognetti, Sapienza University of Rome, 00185 Rome, Italy
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24
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Becerra-Rivera VA, Dunn MF. Polyamine biosynthesis and biological roles in rhizobia. FEMS Microbiol Lett 2019; 366:5476500. [DOI: 10.1093/femsle/fnz084] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2019] [Accepted: 04/22/2019] [Indexed: 12/31/2022] Open
Abstract
ABSTRACTPolyamines are ubiquitous molecules containing two or more amino groups that fulfill varied and often essential physiological and regulatory roles in all organisms. In the symbiotic nitrogen-fixing bacteria known as rhizobia, putrescine and homospermidine are invariably produced while spermidine and norspermidine synthesis appears to be restricted to the alfalfa microsymbiont Sinorhizobium meliloti. Studies with rhizobial mutants deficient in the synthesis of one or more polyamines have shown that these compounds are important for growth, stress resistance, motility, exopolysaccharide production and biofilm formation. In this review, we describe these studies and examine how polyamines are synthesized and regulated in rhizobia.
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Affiliation(s)
- Victor A Becerra-Rivera
- Programa de Genómica Funcional de Procariotes, Centro de Ciencias Genómicas-Universidad Nacional Autónoma de México, Cuernavaca, Morelos, C.P. 62210, Mexico
| | - Michael F Dunn
- Programa de Genómica Funcional de Procariotes, Centro de Ciencias Genómicas-Universidad Nacional Autónoma de México, Cuernavaca, Morelos, C.P. 62210, Mexico
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Spermidine plays a significant role in stabilizing a master transcription factor Clp to promote antifungal activity in Lysobacter enzymogenes. Appl Microbiol Biotechnol 2019; 103:1811-1822. [PMID: 30617535 DOI: 10.1007/s00253-018-09596-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2018] [Revised: 12/18/2018] [Accepted: 12/19/2018] [Indexed: 01/26/2023]
Abstract
Spermidine is a common polyamine compound produced in bacteria, but its roles remain poorly understood. The bacterial SpeD encodes an S-adenosylmethionine decarboxylase that participates in spermidine synthesis. Lysobacter enzymogenes is an efficient environmental predator of crop fungal pathogens by secreting an antifungal antibiotic HSAF (heat-stable antifungal factor), while Clp is a master transcription factor essential for the antifungal activity of L. enzymogenes. In this work, we observed that speD was a close genomic neighbor of the clp gene. This genomic arrangement also seems to occur in many other bacteria, but the underlying reason remains unclear. By using L. enzymogenes OH11 as a working model, we showed that SpeD was involved in spermidine production that was essential for the L. enzymogenes antifungal activity. Spermidine altered the bacterial growth capability and HSAF production, both of which critically contributed to the L. enzymogenes antifungal activity. We further found that spermidine in L. enzymogenes was able to play a crucial, yet indirect role in maintaining the Clp level in vivo, at least partially accounting for its role in the antifungal activity. Thus, our findings suggested that spermidine probably plays an uncharacterized role in maintaining the levels of the master transcription regulator Clp to optimize its role in antifungal activity in an agriculturally beneficial bacterium.
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Abstract
Bacterial signal transduction systems are responsible for sensing environmental cues and adjusting the cellular behaviour and/or metabolism in response to these cues. They also monitor the intracellular conditions and the status of the cell envelope and the cytoplasmic membrane and trigger various stress responses to counteract adverse changes. This surveillance involves several classes of sensor proteins: histidine kinases; chemoreceptors; membrane components of the sugar phosphotransferase system; adenylate, diadenylate and diguanylate cyclases and certain cAMP, c-di-AMP and c-di-GMP phosphodiesterases; extracytoplasmic function sigma factors and Ser/Thr/Tyr protein kinases and phosphoprotein phosphatases. We have compiled a detailed listing of sensor proteins that are encoded in the genomes of Escherichia coli, Bacillus subtilis and 10 widespread pathogens: Chlamydia trachomatis, Haemophilus influenzae, Helicobacter pylori, Mycobacterium tuberculosis, Mycoplasma pneumoniae, Neisseria gonorrhoeae, Porphyromonas gingivalis, Rickettsia typhi, Streptococcus pyogenes and Treponema pallidum, and checked what, if anything, is known about their functions. This listing shows significant gaps in the understanding of which environmental and intracellular cues are perceived by these bacteria and which cellular responses are triggered by the changes in the respective parameters. A better understanding of bacterial preferences may suggest new ways to modulate the expression of virulence factors and therefore decrease the reliance on antibiotics to fight infection.
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Affiliation(s)
- Michael Y Galperin
- National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, MD, USA
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27
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Abstract
Most of the phylogenetic diversity of life is found in bacteria and archaea, and is reflected in the diverse metabolism and functions of bacterial and archaeal polyamines. The polyamine spermidine was probably present in the last universal common ancestor, and polyamines are known to be necessary for critical physiological functions in bacteria, such as growth, biofilm formation, and other surface behaviors, and production of natural products, such as siderophores. There is also phylogenetic diversity of function, indicated by the role of polyamines in planktonic growth of different species, ranging from absolutely essential to entirely dispensable. However, the cellular molecular mechanisms responsible for polyamine function in bacterial growth are almost entirely unknown. In contrast, the molecular mechanisms of essential polyamine functions in archaea are better understood: covalent modification by polyamines of translation factor aIF5A and the agmatine modification of tRNAIle As with bacterial hyperthermophiles, archaeal thermophiles require long-chain and branched polyamines for growth at high temperatures. For bacterial species in which polyamines are essential for growth, it is still unknown whether the molecular mechanisms underpinning polyamine function involve covalent or noncovalent interactions. Understanding the cellular molecular mechanisms of polyamine function in bacterial growth and physiology remains one of the great challenges for future polyamine research.
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Affiliation(s)
- Anthony J Michael
- From the Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, Texas 75390
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Cakar F, Zingl FG, Schild S. Silence is golden: gene silencing of V. cholerae during intestinal colonization delivers new aspects to the acid tolerance response. Gut Microbes 2018; 10:228-234. [PMID: 30110191 PMCID: PMC6546326 DOI: 10.1080/19490976.2018.1502538] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/30/2018] [Revised: 06/20/2018] [Accepted: 07/09/2018] [Indexed: 02/03/2023] Open
Abstract
Bacterial pathogens of the gastrointestinal tract alter their expression profile upon ingestion by the host and activate a variety of factors enhancing colonization and virulence. However, gene silencing during infection might be as important as gene activation to achieve full colonization fitness. Thus, we developed and successfully applied a reporter technology to identify 101 in vivo repressed (ivr) genes of the bacterial pathogen Vibrio cholerae. In depth analysis of the in vivo repressed H+/Cl- transporter ClcA revealed an inverse requirement along gastrointestinal colonization. ClcA could be linked to acid tolerance response required during stomach passage, but ClcA expression is detrimental during subsequent colonization of the lower intestinal tract as it exploits the proton-motive force in alkaline environments. The study summarized in this addendum demonstrates that constitutive expression of ivr genes can reduce intestinal colonization fitness of V. cholerae, highlighting the necessity to downregulate these genes in vivo.
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Affiliation(s)
- Fatih Cakar
- Institute of Molecular Biosciences, University of Graz, Graz, Austria
| | - Franz G. Zingl
- Institute of Molecular Biosciences, University of Graz, Graz, Austria
| | - Stefan Schild
- Institute of Molecular Biosciences, University of Graz, Graz, Austria
- BioTechMed-Graz, Austria
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Kera K, Nagayama T, Nanatani K, Saeki-Yamoto C, Tominaga A, Souma S, Miura N, Takeda K, Kayamori S, Ando E, Higashi K, Igarashi K, Uozumi N. Reduction of Spermidine Content Resulting from Inactivation of Two Arginine Decarboxylases Increases Biofilm Formation in Synechocystis sp. Strain PCC 6803. J Bacteriol 2018; 200:e00664-17. [PMID: 29440257 PMCID: PMC5892111 DOI: 10.1128/jb.00664-17] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2017] [Accepted: 02/09/2018] [Indexed: 12/14/2022] Open
Abstract
The phototropic bacterium Synechocystis sp. strain PCC 6803 is able to adapt its morphology in order to survive in a wide range of harsh environments. Under conditions of high salinity, planktonic cells formed cell aggregates in culture. Further observations using crystal violet staining, confocal laser scanning microscopy, and field emission-scanning electron microscopy confirmed that these aggregates were Synechocystis biofilms. Polyamines have been implicated in playing a role in biofilm formation, and during salt stress the content of spermidine, the major polyamine in Synechocystis, was reduced. Two putative arginine decarboxylases, Adc1 and Adc2, in Synechocystis were heterologously expressed in Escherichia coli and purified. Adc2 had high arginine decarboxylase activity, whereas Adc1 was much less active. Disruption of the adc genes in Synechocystis resulted in decreased spermidine content and formation of biofilms even under nonstress conditions. Based on the characterization of the adc mutants, Adc2 was the major arginine decarboxylase whose activity led to inhibition of biofilm formation, and Adc1 contributed only minimally to the process of polyamine synthesis. Taken together, in Synechocystis the shift from planktonic lifestyle to biofilm formation was correlated with a decrease in intracellular polyamine content, which is the inverse relationship of what was previously reported in heterotroph bacteria.IMPORTANCE There are many reports concerning biofilm formation in heterotrophic bacteria. In contrast, studies on biofilm formation in cyanobacteria are scarce. Here, we report on the induction of biofilm formation by salt stress in the model phototrophic bacterium Synechocystis sp. strain PCC 6803. Two arginine decarboxylases (Adc1 and Adc2) possess function in the polyamine synthesis pathway. Inactivation of the adc1 and adc2 genes leads to biofilm formation even in the absence of salt. The shift from planktonic culture to biofilm formation is regulated by a decrease in spermidine content in Synechocystis This negative correlation between biofilm formation and polyamine content, which is the opposite of the relationship reported in other bacteria, is important not only in autotrophic but also in heterotrophic bacteria.
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Affiliation(s)
- Kota Kera
- Department of Biomolecular Engineering, Graduate School of Engineering, Tohoku University, Sendai, Japan
| | - Tatsuya Nagayama
- Department of Biomolecular Engineering, Graduate School of Engineering, Tohoku University, Sendai, Japan
| | - Kei Nanatani
- Department of Biomolecular Engineering, Graduate School of Engineering, Tohoku University, Sendai, Japan
| | - Chika Saeki-Yamoto
- Department of Biomolecular Engineering, Graduate School of Engineering, Tohoku University, Sendai, Japan
| | - Akira Tominaga
- Department of Biomolecular Engineering, Graduate School of Engineering, Tohoku University, Sendai, Japan
| | - Satoshi Souma
- Department of Biomolecular Engineering, Graduate School of Engineering, Tohoku University, Sendai, Japan
| | - Nozomi Miura
- Department of Biomolecular Engineering, Graduate School of Engineering, Tohoku University, Sendai, Japan
| | - Kota Takeda
- Department of Biomolecular Engineering, Graduate School of Engineering, Tohoku University, Sendai, Japan
- Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya, Japan
| | - Syunsuke Kayamori
- Department of Biomolecular Engineering, Graduate School of Engineering, Tohoku University, Sendai, Japan
| | - Eiji Ando
- Clinical and Biotechnology B.U., Shimadzu Corporation, Kyoto, Japan
| | - Kyohei Higashi
- Graduate School of Pharmaceutical Sciences, Chiba University, Chiba, Japan
| | - Kazuei Igarashi
- Graduate School of Pharmaceutical Sciences, Chiba University, Chiba, Japan
| | - Nobuyuki Uozumi
- Department of Biomolecular Engineering, Graduate School of Engineering, Tohoku University, Sendai, Japan
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30
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Abstract
Bacterial cyclic di-GMP signaling networks often consist of dozens of components, and the majority of these components have no observable function. Dahlstrom et al. (J. Bacteriol. 200:e00703-17, 2018, https://doi.org/10.1128/JB.00703-17) explored the function of every component of the Pseudomonas fluorescens cyclic di-GMP network under 188 different growth conditions and identified activities for 80% of the network. They further demonstrated that multiple mechanisms function in tandem to control the activity of the network in different environments.
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31
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Wotanis CK, Brennan WP, Angotti AD, Villa EA, Zayner JP, Mozina AN, Rutkovsky AC, Sobe RC, Bond WG, Karatan E. Relative contributions of norspermidine synthesis and signaling pathways to the regulation of Vibrio cholerae biofilm formation. PLoS One 2017; 12:e0186291. [PMID: 29045455 PMCID: PMC5646818 DOI: 10.1371/journal.pone.0186291] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2017] [Accepted: 09/28/2017] [Indexed: 01/22/2023] Open
Abstract
The polyamine norspermidine is one of the major polyamines synthesized by Vibrionales and has also been found in various aquatic organisms. Norspermidine is among the environmental signals that positively regulate Vibrio cholerae biofilm formation. The NspS/MbaA signaling complex detects extracellular norspermidine and mediates the response to this polyamine. Norspermidine binding to the NspS periplasmic binding protein is thought to inhibit the phosphodiesterase activity of MbaA, increasing levels of the biofilm-promoting second messenger cyclic diguanylate monophosphate, thus enhancing biofilm formation. V. cholerae can also synthesize norspermidine using the enzyme NspC as well as import it from the environment. Deletion of the nspC gene was shown to reduce accumulation of bacteria in biofilms, leading to the conclusion that intracellular norspermidine is also a positive regulator of biofilm formation. Because V. cholerae uses norspermidine to synthesize the siderophore vibriobactin it is possible that intracellular norspermidine is required to obtain sufficient amounts of iron, which is also necessary for robust biofilm formation. The objective of this study was to assess the relative contributions of intracellular and extracellular norspermidine to the regulation of biofilm formation in V. cholerae. We show the biofilm defect of norspermidine synthesis mutants does not result from an inability to produce vibriobactin as vibriobactin synthesis mutants do not have diminished biofilm forming abilities. Furthermore, our work shows that extracellular, but not intracellular norspermidine, is mainly responsible for promoting biofilm formation. We establish that the NspS/MbaA signaling complex is the dominant mediator of biofilm formation in response to extracellular norspermidine, rather than norspermidine synthesized by NspC or imported into the cell.
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Affiliation(s)
- Caitlin K. Wotanis
- Department of Biology, Appalachian State University, Boone, North Carolina, United States of America
| | - William P. Brennan
- Department of Biology, Appalachian State University, Boone, North Carolina, United States of America
| | - Anthony D. Angotti
- Department of Biology, Appalachian State University, Boone, North Carolina, United States of America
| | - Elizabeth A. Villa
- Department of Biology, Appalachian State University, Boone, North Carolina, United States of America
| | - Josiah P. Zayner
- Department of Biology, Appalachian State University, Boone, North Carolina, United States of America
| | - Alexandra N. Mozina
- Department of Biology, Appalachian State University, Boone, North Carolina, United States of America
| | - Alexandria C. Rutkovsky
- Department of Biology, Appalachian State University, Boone, North Carolina, United States of America
| | - Richard C. Sobe
- Department of Biology, Appalachian State University, Boone, North Carolina, United States of America
| | - Whitney G. Bond
- Department of Biology, Appalachian State University, Boone, North Carolina, United States of America
| | - Ece Karatan
- Department of Biology, Appalachian State University, Boone, North Carolina, United States of America
- * E-mail:
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