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Kirchner L, Averhoff B. DNA binding by pilins and their interaction with the inner membrane platform of the DNA transporter in Thermus thermophilus. BIOCHIMICA ET BIOPHYSICA ACTA. BIOMEMBRANES 2022; 1864:183818. [PMID: 34774498 DOI: 10.1016/j.bbamem.2021.183818] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/10/2021] [Revised: 10/13/2021] [Accepted: 11/05/2021] [Indexed: 06/13/2023]
Abstract
The natural transformation system of Thermus thermophilus has become a model system for studies of the structure and function of DNA transporter in thermophilic bacteria. The DNA transporter in T. thermophilus is functionally linked to type IV pili (T4P) and the major pilin PilA4 plays an essential role in both systems. However, T4P are dispensable for natural transformation. In addition to pilA4, T. thermophilus has a gene cluster encoding the three additional pilins PilA1-PilA3; deletion of the cluster abolished natural transformation but retained T4P biogenesis. In this study, we investigated the roles of single pilins PilA1, PilA2 and PilA3 in natural transformation by mutant studies. These studies revealed that each of these pilins is essential for natural transformation. Two of the pilins, PilA1 and PilA2, were found to bind dsDNA. PilA1 and PilA3 were detected in the inner membrane (IM) but not in the outer membrane (OM) whereas PilA2 was present in both membranes. All three pilins where absent in pilus fractions. This suggests that the pilins form a short DNA binding pseudopilus anchored in the IM. PilA1 was found to bind to the IM assembly platform of the DNA transporter via PilM and PilO. These data are in line with the hypothesis that a DNA binding pseudopilus is connected via an IM platform to the cytosolic motor ATPase PilF.
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Affiliation(s)
- Lennart Kirchner
- Molecular Microbiology & Bioenergetics, Institute of Molecular Biosciences, Johann Wolfgang Goethe University Frankfurt/Main, Max-von-Laue-Str. 9, 60438 Frankfurt, Germany
| | - Beate Averhoff
- Molecular Microbiology & Bioenergetics, Institute of Molecular Biosciences, Johann Wolfgang Goethe University Frankfurt/Main, Max-von-Laue-Str. 9, 60438 Frankfurt, Germany.
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2
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Neuhaus A, Selvaraj M, Salzer R, Langer JD, Kruse K, Kirchner L, Sanders K, Daum B, Averhoff B, Gold VAM. Cryo-electron microscopy reveals two distinct type IV pili assembled by the same bacterium. Nat Commun 2020; 11:2231. [PMID: 32376942 PMCID: PMC7203116 DOI: 10.1038/s41467-020-15650-w] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2019] [Accepted: 03/19/2020] [Indexed: 12/19/2022] Open
Abstract
Type IV pili are flexible filaments on the surface of bacteria, consisting of a helical assembly of pilin proteins. They are involved in bacterial motility (twitching), surface adhesion, biofilm formation and DNA uptake (natural transformation). Here, we use cryo-electron microscopy and mass spectrometry to show that the bacterium Thermus thermophilus produces two forms of type IV pilus ('wide' and 'narrow'), differing in structure and protein composition. Wide pili are composed of the major pilin PilA4, while narrow pili are composed of a so-far uncharacterized pilin which we name PilA5. Functional experiments indicate that PilA4 is required for natural transformation, while PilA5 is important for twitching motility.
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Affiliation(s)
- Alexander Neuhaus
- Living Systems Institute, University of Exeter, Stocker Road, Exeter, EX4 4QD, UK
- College of Life and Environmental Sciences, Geoffrey Pope, University of Exeter, Stocker Road, Exeter, EX4 4QD, UK
| | - Muniyandi Selvaraj
- Department of Structural Biology, Max Planck Institute of Biophysics, Max-von-Laue Str. 3, 60438, Frankfurt am Main, Germany
- Laboratory of Structural Biology, Helsinki Institute of Life Science, 00014 University of Helsinki, Helsinki, Finland
| | - Ralf Salzer
- Molecular Microbiology and Bioenergetics, Institute of Molecular Biosciences, Goethe University Frankfurt, Max-von-Laue Str. 9, 60438, Frankfurt am Main, Germany
- Structural Studies Division, Medical Research Council-Laboratory of Molecular Biology, Cambridge Biomedical Campus, Francis Crick Ave, Cambridge, CB2 0QH, UK
| | - Julian D Langer
- Department of Molecular Membrane Biology, Max Planck Institute of Biophysics, Max-von-Laue Str. 3, 60438, Frankfurt am Main, Germany
- Proteomics, Max Planck Institute for Brain Research, Max-von-Laue Str. 4, 60438, Frankfurt am Main, Germany
| | - Kerstin Kruse
- Molecular Microbiology and Bioenergetics, Institute of Molecular Biosciences, Goethe University Frankfurt, Max-von-Laue Str. 9, 60438, Frankfurt am Main, Germany
| | - Lennart Kirchner
- Molecular Microbiology and Bioenergetics, Institute of Molecular Biosciences, Goethe University Frankfurt, Max-von-Laue Str. 9, 60438, Frankfurt am Main, Germany
| | - Kelly Sanders
- Living Systems Institute, University of Exeter, Stocker Road, Exeter, EX4 4QD, UK
- College of Life and Environmental Sciences, Geoffrey Pope, University of Exeter, Stocker Road, Exeter, EX4 4QD, UK
| | - Bertram Daum
- Living Systems Institute, University of Exeter, Stocker Road, Exeter, EX4 4QD, UK
- College of Life and Environmental Sciences, Geoffrey Pope, University of Exeter, Stocker Road, Exeter, EX4 4QD, UK
| | - Beate Averhoff
- Molecular Microbiology and Bioenergetics, Institute of Molecular Biosciences, Goethe University Frankfurt, Max-von-Laue Str. 9, 60438, Frankfurt am Main, Germany
| | - Vicki A M Gold
- Living Systems Institute, University of Exeter, Stocker Road, Exeter, EX4 4QD, UK.
- College of Life and Environmental Sciences, Geoffrey Pope, University of Exeter, Stocker Road, Exeter, EX4 4QD, UK.
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3
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Keller H, Kruse K, Averhoff B, Duchardt-Ferner E, Wöhnert J. NMR resonance assignments for the GSPII-C domain of the PilF ATPase from Thermus thermophilus in complex with c-di-GMP. BIOMOLECULAR NMR ASSIGNMENTS 2019; 13:361-366. [PMID: 31372934 DOI: 10.1007/s12104-019-09906-w] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/29/2019] [Accepted: 07/27/2019] [Indexed: 06/10/2023]
Abstract
The natural transformation system of the thermophilic bacterium Thermus thermophilus is one of the most efficient DNA transport systems in terms of DNA uptake rate and promiscuity. The DNA transporter of T. thermophilus plays an important role in interdomain DNA transfer in hot environments. PilF is the traffic ATPase that provides the energy for the assembly of the DNA translocation machinery and the functionally linked type IV pilus system in T. thermophilus. In contrast to other known traffic ATPases, the N-terminal region of PilF harbors three consecutive domains with homology to general secretory pathway II (GSPII) domains. These GSPII-like domains influence pilus assembly, twitching motility and transformation efficiency. A structural homolog of the PilF GSPII-like domains, the N-terminal domain of the traffic ATPase MshE from Vibrio cholerae, was recently crystallized in complex with the bacterial second messenger c-di-GMP. In order to study the consequences of c-di-GMP binding on the three-dimensional architecture of PilF, we initiated structural studies on the PilF GSPII-like domains. Here, we present the 1H, 13C and 15N chemical shift assignments for the isolated PilF GSPII-C domain from T. thermophilus in complex with c-di-GMP. In addition, the structural dynamics of the complex was investigated in an {1H},15N-hetNOE experiment.
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Affiliation(s)
- Heiko Keller
- Institute for Molecular Biosciences, Goethe University Frankfurt/M, Max-von-Laue-Str. 9, 60438, Frankfurt, Germany.
- Center for Biomolecular Magnetic Resonance (BMRZ), Goethe University Frankfurt/M, Max-von-Laue-Str. 9, 60438, Frankfurt, Germany.
| | - Kerstin Kruse
- Institute for Molecular Biosciences, Goethe University Frankfurt/M, Max-von-Laue-Str. 9, 60438, Frankfurt, Germany
| | - Beate Averhoff
- Institute for Molecular Biosciences, Goethe University Frankfurt/M, Max-von-Laue-Str. 9, 60438, Frankfurt, Germany
| | - Elke Duchardt-Ferner
- Institute for Molecular Biosciences, Goethe University Frankfurt/M, Max-von-Laue-Str. 9, 60438, Frankfurt, Germany
- Center for Biomolecular Magnetic Resonance (BMRZ), Goethe University Frankfurt/M, Max-von-Laue-Str. 9, 60438, Frankfurt, Germany
| | - Jens Wöhnert
- Institute for Molecular Biosciences, Goethe University Frankfurt/M, Max-von-Laue-Str. 9, 60438, Frankfurt, Germany.
- Center for Biomolecular Magnetic Resonance (BMRZ), Goethe University Frankfurt/M, Max-von-Laue-Str. 9, 60438, Frankfurt, Germany.
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Neißner K, Keller H, Duchardt-Ferner E, Hacker C, Kruse K, Averhoff B, Wöhnert J. NMR resonance assignments for the GSPII-B domain of the traffic ATPase PilF from Thermus thermophilus in the apo and the c-di-GMP-bound state. BIOMOLECULAR NMR ASSIGNMENTS 2019; 13:383-390. [PMID: 31432400 DOI: 10.1007/s12104-019-09911-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/03/2019] [Accepted: 08/14/2019] [Indexed: 06/10/2023]
Abstract
The PilF protein from the thermophilic bacterium Thermus thermophilus is a traffic ATPase powering the assembly of the DNA translocation machinery as well as of type 4 pili. Thereby PilF mediates the natural transformability of T. thermophilus. PilF contains a C-terminal ATPase domain and three N-terminal domains with partial homology to so-called general secretory pathway II (GSPII) domains. These three GSPII domains (GSPII-A, GSPII-B and GSPII-C) are essential for pilus assembly and twitching motility. They show varying degrees of sequence homology to the N-terminal domain of the ATPase MshE from Vibrio cholerae which binds the bacterial second messenger molecule c-di-GMP. NMR experiments demonstrate that the GSPII-B domain of PilF also binds c-di-GMP with high affinity and forms a 1:1 complex in slow exchange on the NMR time scale. As a prerequisite for structural studies of c-di-GMP binding to the GSPII-B domain of T. thermophilus PilF we present here the NMR resonance assignments for the apo and the c-di-GMP bound state of GSPII-B. In addition, we map the binding site for c-di-GMP on the GSPII-B domain using chemical shift perturbation data and compare the dynamics of the apo and the c-di-GMP-bound state of the GSPII-B domain based on {1H},15N-hetNOE data.
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Affiliation(s)
- Konstantin Neißner
- Institute for Molecular Biosciences, Goethe-University Frankfurt/M., Max-von-Laue-Str. 9, 60438, Frankfurt, Germany.
- Center for Biomolecular Magnetic Resonance (BMRZ), Goethe-University Frankfurt/M., Max-von-Laue-Str. 9, 60438, Frankfurt, Germany.
| | - Heiko Keller
- Institute for Molecular Biosciences, Goethe-University Frankfurt/M., Max-von-Laue-Str. 9, 60438, Frankfurt, Germany
- Center for Biomolecular Magnetic Resonance (BMRZ), Goethe-University Frankfurt/M., Max-von-Laue-Str. 9, 60438, Frankfurt, Germany
| | - Elke Duchardt-Ferner
- Institute for Molecular Biosciences, Goethe-University Frankfurt/M., Max-von-Laue-Str. 9, 60438, Frankfurt, Germany
- Center for Biomolecular Magnetic Resonance (BMRZ), Goethe-University Frankfurt/M., Max-von-Laue-Str. 9, 60438, Frankfurt, Germany
| | - Carolin Hacker
- Institute for Molecular Biosciences, Goethe-University Frankfurt/M., Max-von-Laue-Str. 9, 60438, Frankfurt, Germany
- Center for Biomolecular Magnetic Resonance (BMRZ), Goethe-University Frankfurt/M., Max-von-Laue-Str. 9, 60438, Frankfurt, Germany
| | - Kerstin Kruse
- Molecular Microbiology and Bioenergetics, Institute for Molecular Biosciences, Goethe-University Frankfurt/M., Max-von-Laue-Str. 9, 60438, Frankfurt, Germany
| | - Beate Averhoff
- Molecular Microbiology and Bioenergetics, Institute for Molecular Biosciences, Goethe-University Frankfurt/M., Max-von-Laue-Str. 9, 60438, Frankfurt, Germany
| | - Jens Wöhnert
- Institute for Molecular Biosciences, Goethe-University Frankfurt/M., Max-von-Laue-Str. 9, 60438, Frankfurt, Germany.
- Center for Biomolecular Magnetic Resonance (BMRZ), Goethe-University Frankfurt/M., Max-von-Laue-Str. 9, 60438, Frankfurt, Germany.
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5
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Kruse K, Salzer R, Averhoff B. The traffic ATPase PilF interacts with the inner membrane platform of the DNA translocator and type IV pili from Thermus thermophilus. FEBS Open Bio 2018; 9:4-17. [PMID: 30652069 PMCID: PMC6325625 DOI: 10.1002/2211-5463.12548] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2018] [Revised: 10/10/2018] [Accepted: 10/25/2018] [Indexed: 12/20/2022] Open
Abstract
A major driving force for the adaptation of bacteria to changing environments is the uptake of naked DNA from the environment by natural transformation, which allows the acquisition of new capabilities. Uptake of the high molecular weight DNA is mediated by a complex transport machinery that spans the entire cell periphery. This DNA translocator catalyzes the binding and splitting of double‐stranded DNA and translocation of single‐stranded DNA into the cytoplasm, where it is recombined with the chromosome. The thermophilic bacterium Thermus thermophilus exhibits the highest transformation frequencies reported and is a model system to analyze the structure and function of this macromolecular transport machinery. Transport activity is powered by the traffic ATPase PilF, a soluble protein that forms hexameric complexes. Here, we demonstrate that PilF physically binds to an inner membrane assembly platform of the DNA translocator, comprising PilMNO, via the ATP‐binding protein PilM. Binding to PilMNO or PilMN stimulates the ATPase activity of PilF ~ 2‐fold, whereas there is no stimulation when binding to PilM or PilN alone. A PilMK26A variant defective in ATP binding still binds PilF and, together with PilN, stimulates PilF‐mediated ATPase activity. PilF is unique in having three conserved GSPII (general secretory pathway II) domains (A–C) at its N terminus. Deletion analyses revealed that none of the GSPII domains is essential for binding PilMN, but GSPIIC is essential for PilMN‐mediated stimulation of ATP hydrolysis by PilF. Our data suggest that PilM is a coupling protein that physically and functionally connects the soluble motor ATPase PilF to the DNA translocator via the PilMNO assembly platform.
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Affiliation(s)
- Kerstin Kruse
- Molecular Microbiology & Bioenergetics Institute of Molecular Biosciences Goethe University Frankfurt Germany
| | - Ralf Salzer
- Molecular Microbiology & Bioenergetics Institute of Molecular Biosciences Goethe University Frankfurt Germany.,Present address: Structural Studies Division Medical Research Council - Laboratory of Molecular Biology Cambridge Biomedical Campus, Francis Crick Ave Cambridge CB2 OQH UK
| | - Beate Averhoff
- Molecular Microbiology & Bioenergetics Institute of Molecular Biosciences Goethe University Frankfurt Germany
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6
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Functional dissection of the three N-terminal general secretory pathway domains and the Walker motifs of the traffic ATPase PilF from Thermus thermophilus. Extremophiles 2018; 22:461-471. [PMID: 29464394 DOI: 10.1007/s00792-018-1008-9] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2017] [Accepted: 02/05/2018] [Indexed: 01/25/2023]
Abstract
The traffic ATPase PilF of Thermus thermophilus powers pilus assembly as well as uptake of DNA. PilF differs from other traffic ATPases by a triplicated general secretory pathway II, protein E, N-terminal domain (GSPIIABC). We investigated the in vivo and in vitro roles of the GSPII domains, the Walker A motif and a catalytic glutamate by analyzing a set of PilF deletion derivatives and pilF mutants. Here, we report that PilF variants devoid of the first two or all three GSPII domains do not form stable hexamers indicating a role of the triplicated GSPII domain in complex formation and/or stability. A pilFΔGSPIIC mutant was significantly impaired in piliation which leads to the conclusion that the GSPIIC domain plays a vital role in pilus assembly. Interestingly, the pilFΔGSPIIC mutant was hypertransformable. This suggests that GSPIIC strongly affects transformation efficiency. A pilF∆GSPIIA mutant exhibited wild-type piliation but reduced pilus-mediated twitching motility, suggesting that GSPIIA plays a role in pilus dynamics. Furthermore, we report that pilF mutants with a defect in the ATP binding Walker A motif or in the catalytic glutamate residue are defective in piliation and natural transformation. These findings show that both, ATP binding and hydrolysis, are essential for the dual function of PilF in natural transformation and pilus assembly.
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7
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D'Imprima E, Salzer R, Bhaskara RM, Sánchez R, Rose I, Kirchner L, Hummer G, Kühlbrandt W, Vonck J, Averhoff B. Cryo-EM structure of the bifunctional secretin complex of Thermus thermophilus. eLife 2017; 6. [PMID: 29280731 PMCID: PMC5745081 DOI: 10.7554/elife.30483] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2017] [Accepted: 12/13/2017] [Indexed: 11/13/2022] Open
Abstract
Secretins form multimeric channels across the outer membrane of Gram-negative bacteria that mediate the import or export of substrates and/or extrusion of type IV pili. The secretin complex of Thermus thermophilus is an oligomer of the 757-residue PilQ protein, essential for DNA uptake and pilus extrusion. Here, we present the cryo-EM structure of this bifunctional complex at a resolution of ~7 Å using a new reconstruction protocol. Thirteen protomers form a large periplasmic domain of six stacked rings and a secretin domain in the outer membrane. A homology model of the PilQ protein was fitted into the cryo-EM map. A crown-like structure outside the outer membrane capping the secretin was found not to be part of PilQ. Mutations in the secretin domain disrupted the crown and abolished DNA uptake, suggesting a central role of the crown in natural transformation.
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Affiliation(s)
- Edoardo D'Imprima
- Department of Structural Biology, Max Planck Institute of Biophysics, Frankfurt, Germany
| | - Ralf Salzer
- Molecular Microbiology and Bioenergetics, Institute of Molecular Biosciences, Goethe University Frankfurt, Frankfurt, Germany
| | - Ramachandra M Bhaskara
- Department of Theoretical Biophysics, Max Planck Institute of Biophysics, Frankfurt, Germany
| | - Ricardo Sánchez
- Sofja Kovalevskaja Group, Max Planck Institute of Biophysics, Frankfurt, Germany
| | - Ilona Rose
- Molecular Microbiology and Bioenergetics, Institute of Molecular Biosciences, Goethe University Frankfurt, Frankfurt, Germany
| | - Lennart Kirchner
- Molecular Microbiology and Bioenergetics, Institute of Molecular Biosciences, Goethe University Frankfurt, Frankfurt, Germany
| | - Gerhard Hummer
- Department of Theoretical Biophysics, Max Planck Institute of Biophysics, Frankfurt, Germany.,Institute of Biophysics, Goethe University Frankfurt, Frankfurt, Germany
| | - Werner Kühlbrandt
- Department of Structural Biology, Max Planck Institute of Biophysics, Frankfurt, Germany
| | - Janet Vonck
- Department of Structural Biology, Max Planck Institute of Biophysics, Frankfurt, Germany
| | - Beate Averhoff
- Molecular Microbiology and Bioenergetics, Institute of Molecular Biosciences, Goethe University Frankfurt, Frankfurt, Germany
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The type IV pilus assembly ATPase PilB functions as a signaling protein to regulate exopolysaccharide production in Myxococcus xanthus. Sci Rep 2017; 7:7263. [PMID: 28779124 PMCID: PMC5544727 DOI: 10.1038/s41598-017-07594-x] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2017] [Accepted: 06/28/2017] [Indexed: 12/12/2022] Open
Abstract
Myxococcus xanthus possesses a form of surface motility powered by the retraction of the type IV pilus (T4P). Additionally, exopolysaccharide (EPS), the major constituent of bacterial biofilms, is required for this T4P-mediated motility in M. xanthus as the putative trigger of T4P retraction. The results here demonstrate that the T4P assembly ATPase PilB functions as an intermediary in the EPS regulatory pathway composed of the T4P upstream of the Dif signaling proteins in M. xanthus. A suppressor screen isolated a pilB mutation that restored EPS production to a T4P− mutant. An additional PilB mutant variant, which is deficient in ATP hydrolysis and T4P assembly, supports EPS production without the T4P, indicating PilB can regulate EPS production independently of its function in T4P assembly. Further analysis confirms that PilB functions downstream of the T4P filament but upstream of the Dif proteins. In vitro studies suggest that the nucleotide-free form of PilB assumes the active signaling conformation in EPS regulation. Since M. xanthus PilB possesses conserved motifs with high affinity for c-di-GMP binding, the findings here suggest that c-di-GMP can regulate both motility and biofilm formation through a single effector in this surface-motile bacterium.
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9
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Tripathi C, Mishra H, Khurana H, Dwivedi V, Kamra K, Negi RK, Lal R. Complete Genome Analysis of Thermus parvatiensis and Comparative Genomics of Thermus spp. Provide Insights into Genetic Variability and Evolution of Natural Competence as Strategic Survival Attributes. Front Microbiol 2017; 8:1410. [PMID: 28798737 PMCID: PMC5529391 DOI: 10.3389/fmicb.2017.01410] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2017] [Accepted: 07/11/2017] [Indexed: 01/27/2023] Open
Abstract
Thermophilic environments represent an interesting niche. Among thermophiles, the genus Thermus is among the most studied genera. In this study, we have sequenced the genome of Thermus parvatiensis strain RL, a thermophile isolated from Himalayan hot water springs (temperature >96°C) using PacBio RSII SMRT technique. The small genome (2.01 Mbp) comprises a chromosome (1.87 Mbp) and a plasmid (143 Kbp), designated in this study as pTP143. Annotation revealed a high number of repair genes, a squeezed genome but containing highly plastic plasmid with transposases, integrases, mobile elements and hypothetical proteins (44%). We performed a comparative genomic study of the group Thermus with an aim of analysing the phylogenetic relatedness as well as niche specific attributes prevalent among the group. We compared the reference genome RL with 16 Thermus genomes to assess their phylogenetic relationships based on 16S rRNA gene sequences, average nucleotide identity (ANI), conserved marker genes (31 and 400), pan genome and tetranucleotide frequency. The core genome of the analyzed genomes contained 1,177 core genes and many singleton genes were detected in individual genomes, reflecting a conserved core but adaptive pan repertoire. We demonstrated the presence of metagenomic islands (chromosome:5, plasmid:5) by recruiting raw metagenomic data (from the same niche) against the genomic replicons of T. parvatiensis. We also dissected the CRISPR loci wide all genomes and found widespread presence of this system across Thermus genomes. Additionally, we performed a comparative analysis of competence loci wide Thermus genomes and found evidence for recent horizontal acquisition of the locus and continued dispersal among members reflecting that natural competence is a beneficial survival trait among Thermus members and its acquisition depicts unending evolution in order to accomplish optimal fitness.
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Affiliation(s)
- Charu Tripathi
- Department of Zoology, University of DelhiNew Delhi, India
| | | | - Himani Khurana
- Department of Zoology, University of DelhiNew Delhi, India
| | | | - Komal Kamra
- Ciliate Biology Laboratory, Sri Guru Tegh Bahadar Khalsa College, University of DelhiNew Delhi, India
| | - Ram K Negi
- Department of Zoology, University of DelhiNew Delhi, India
| | - Rup Lal
- Department of Zoology, University of DelhiNew Delhi, India
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10
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Salzer R, D'Imprima E, Gold VAM, Rose I, Drechsler M, Vonck J, Averhoff B. Topology and Structure/Function Correlation of Ring- and Gate-forming Domains in the Dynamic Secretin Complex of Thermus thermophilus. J Biol Chem 2016; 291:14448-56. [PMID: 27226590 DOI: 10.1074/jbc.m116.724153] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2016] [Indexed: 11/06/2022] Open
Abstract
Secretins are versatile outer membrane pores used by many bacteria to secrete proteins, toxins, or filamentous phages; extrude type IV pili (T4P); or take up DNA. Extrusion of T4P and natural transformation of DNA in the thermophilic bacterium Thermus thermophilus requires a unique secretin complex comprising six stacked rings, a membrane-embedded cone structure, and two gates that open and close a central channel. To investigate the role of distinct domains in ring and gate formation, we examined a set of deletion derivatives by cryomicroscopy techniques. Here we report that maintaining the N0 ring in the deletion derivatives led to stable PilQ complexes. Analyses of the variants unraveled that an N-terminal domain comprising a unique βββαβ fold is essential for the formation of gate 2. Furthermore, we identified four βαββα domains essential for the formation of the N2 to N5 rings. Mutant studies revealed that deletion of individual ring domains significantly reduces piliation. The N1, N2, N4, and N5 deletion mutants were significantly impaired in T4P-mediated twitching motility, whereas the motility of the N3 mutant was comparable with that of wild-type cells. This indicates that the deletion of the N3 ring leads to increased pilus dynamics, thereby compensating for the reduced number of pili of the N3 mutant. All mutants exhibit a wild-type natural transformation phenotype, leading to the conclusion that DNA uptake is independent of functional T4P.
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Affiliation(s)
- Ralf Salzer
- From Molecular Microbiology and Bioenergetics, Institute of Molecular Biosciences, Goethe University Frankfurt, 60438 Frankfurt am Main and
| | - Edoardo D'Imprima
- the Department of Structural Biology, Max Planck Institute of Biophysics, 60438 Frankfurt am Main, Germany
| | - Vicki A M Gold
- the Department of Structural Biology, Max Planck Institute of Biophysics, 60438 Frankfurt am Main, Germany
| | - Ilona Rose
- From Molecular Microbiology and Bioenergetics, Institute of Molecular Biosciences, Goethe University Frankfurt, 60438 Frankfurt am Main and
| | - Moritz Drechsler
- From Molecular Microbiology and Bioenergetics, Institute of Molecular Biosciences, Goethe University Frankfurt, 60438 Frankfurt am Main and
| | - Janet Vonck
- the Department of Structural Biology, Max Planck Institute of Biophysics, 60438 Frankfurt am Main, Germany
| | - Beate Averhoff
- From Molecular Microbiology and Bioenergetics, Institute of Molecular Biosciences, Goethe University Frankfurt, 60438 Frankfurt am Main and
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11
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Rule CS, Patrick M, Camberg JL, Maricic N, Hol WG, Sandkvist M. Zinc coordination is essential for the function and activity of the type II secretion ATPase EpsE. Microbiologyopen 2016; 5:870-882. [PMID: 27168165 PMCID: PMC5061722 DOI: 10.1002/mbo3.376] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2016] [Revised: 04/05/2016] [Accepted: 04/11/2016] [Indexed: 11/10/2022] Open
Abstract
The type II secretion system Eps in Vibrio cholerae promotes the extracellular transport of cholera toxin and several hydrolytic enzymes and is a major virulence system in many Gram‐negative pathogens which is structurally related to the type IV pilus system. The cytoplasmic ATPase EpsE provides the energy for exoprotein secretion through ATP hydrolysis. EpsE contains a unique metal‐binding domain that coordinates zinc through a tetracysteine motif (CXXCX29CXXC), which is also present in type IV pilus assembly but not retraction ATPases. Deletion of the entire domain or substitution of any of the cysteine residues that coordinate zinc completely abrogates secretion in an EpsE‐deficient strain and has a dominant negative effect on secretion in the presence of wild‐type EpsE. Consistent with the in vivo data, chemical depletion of zinc from purified EpsE hexamers results in loss of in vitro ATPase activity. In contrast, exchanging the residues between the two dicysteines with those from the homologous ATPase XcpR from Pseudomonas aeruginosa does not have a significant impact on EpsE. These results indicate that, although the individual residues in the metal‐binding domain are generally interchangeable, zinc coordination is essential for the activity and function of EpsE.
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Affiliation(s)
- Chelsea S Rule
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, Michigan
| | - Marcella Patrick
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, Michigan
| | - Jodi L Camberg
- Division of Infectious Diseases, Department of Medicine, University of Maryland School of Medicine, Rockville, Maryland
| | - Natalie Maricic
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, Michigan
| | - Wim G Hol
- Department of Biochemistry, Biomolecular Structure Center, University of Washington, Seattle, Washington
| | - Maria Sandkvist
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, Michigan.
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12
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Gold VAM, Salzer R, Averhoff B, Kühlbrandt W. Structure of a type IV pilus machinery in the open and closed state. eLife 2015; 4. [PMID: 25997099 PMCID: PMC4463427 DOI: 10.7554/elife.07380] [Citation(s) in RCA: 82] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2015] [Accepted: 05/20/2015] [Indexed: 01/20/2023] Open
Abstract
Proteins of the secretin family form large macromolecular complexes, which assemble in the outer membrane of Gram-negative bacteria. Secretins are major components of type II and III secretion systems and are linked to extrusion of type IV pili (T4P) and to DNA uptake. By electron cryo-tomography of whole Thermus thermophilus cells, we determined the in situ structure of a T4P molecular machine in the open and the closed state. Comparison reveals a major conformational change whereby the N-terminal domains of the central secretin PilQ shift by ∼30 Å, and two periplasmic gates open to make way for pilus extrusion. Furthermore, we determine the structure of the assembled pilus. DOI:http://dx.doi.org/10.7554/eLife.07380.001 Gram-negative bacteria can cause serious diseases in humans, such as cholera and bacterial meningitis. These bacteria are surrounded by two membranes: an inner membrane and an outer membrane. Proteins called secretins are components of several large molecular complexes that are embedded within the outer membrane. Some secretin-containing complexes form pores in the bacterial membranes and allow molecules to pass in or out of the cell. Some secretins also form part of the machinery that allow Gram-negative bacteria to grow fibre-like structures called type IV pili. These pili help bacteria that cause infections to move and stick to host cells, where they can also trigger massive changes in the host cells' architecture. Multiple copies of a secretin protein called PilQ form a channel in the outer membrane of the bacteria that allows a type IV pilus to grow out of the surface of the cell. The pilus can then hook the bacteria onto surfaces and other cells. There is evidence to suggest the type IV pilus machinery is involved in the uptake of DNA from other bacteria, an important but poorly understood process that has contributed to the spread of multi-drug resistance. Now, Gold et al. have used a cutting-edge technique called ‘electron cryo-tomography’ to analyse the three-dimensional structure of the machinery that builds the type IV pili in the membranes of a bacterium called Thermus thermophilus. This analysis revealed that, similar to many other channel complexes, the PilQ channel can be ‘open’ or ‘closed’. When pili are absent, the channel is closed, but the channel opens when pili are present. Further analysis also revealed the structure of an assembled pilus. Next, Gold et al. studied the open state of the type IV pilus in more detail and observed that a region of each of the PilQ proteins moves a considerable distance to make way for the pilus to enter the central pore. These results will pave the way for future studies of type IV pili and other secretin-containing complexes and underpin efforts to investigate new drug targets to combat bacterial infections. DOI:http://dx.doi.org/10.7554/eLife.07380.002
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Affiliation(s)
- Vicki A M Gold
- Department of Structural Biology, Max Planck Institute of Biophysics, Frankfurt am Main, Germany
| | - Ralf Salzer
- Molecular Microbiology and Bioenergetics, Institute of Molecular Biosciences, Goethe University Frankfurt, Frankfurt am Main, Germany
| | - Beate Averhoff
- Molecular Microbiology and Bioenergetics, Institute of Molecular Biosciences, Goethe University Frankfurt, Frankfurt am Main, Germany
| | - Werner Kühlbrandt
- Department of Structural Biology, Max Planck Institute of Biophysics, Frankfurt am Main, Germany
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Salzer R, Kern T, Joos F, Averhoff B. The Thermus thermophilus comEA/comEC operon is associated with DNA binding and regulation of the DNA translocator and type IV pili. Environ Microbiol 2015; 18:65-74. [PMID: 25727469 DOI: 10.1111/1462-2920.12820] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2014] [Accepted: 02/20/2015] [Indexed: 11/30/2022]
Abstract
Natural transformation systems and type IV pili are linked in many naturally competent bacteria. In the Gram-negative bacterium Thermus thermophilus, a leading model organism for studies of DNA transporters in thermophilic bacteria, seven competence proteins play a dual role in both systems, whereas two competence genes, comEA and comEC, are suggested to represent unique DNA translocator proteins. Here we show that the T. thermophilus ComEA protein binds dsDNA and is anchored in the inner membrane. comEA is co-transcribed with the flanking comEC gene, and transcription of this operon is upregulated by nutrient limitation and low temperature. To our surprise, a comEC mutant was impaired in piliation. We followed this observation and uncovered that the impaired piliation of the comEC mutant is due to a transcriptional downregulation of pilA4 and the pilN both playing a dual role in piliation and natural competence. Moreover, the comEC mutation resulted in a dramatic decrease in mRNA levels of the pseudopilin gene pilA1, which is unique for the DNA transporter. We conclude that ComEC modulates transcriptional regulation of type IV pili and DNA translocator components thereby mediating a response to extracellular parameters.
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Affiliation(s)
- Ralf Salzer
- Molecular Microbiology and Bioenergetics, Institute of Molecular Biosciences, Goethe University Frankfurt, Frankfurt am Main, Germany
| | - Timo Kern
- Molecular Microbiology and Bioenergetics, Institute of Molecular Biosciences, Goethe University Frankfurt, Frankfurt am Main, Germany
| | - Friederike Joos
- Department of Structural Biology, Max-Planck Institute of Biophysics, Frankfurt am Main, 60438, Germany
| | - Beate Averhoff
- Molecular Microbiology and Bioenergetics, Institute of Molecular Biosciences, Goethe University Frankfurt, Frankfurt am Main, Germany
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14
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Affiliation(s)
- Alain Filloux
- Alain Filloux, MRC Centre for Molecular Bacteriology and Infection, Department of Life Sciences, Imperial College London, London SW7 2AZ, UK; E-mail:
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15
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Berry JL, Pelicic V. Exceptionally widespread nanomachines composed of type IV pilins: the prokaryotic Swiss Army knives. FEMS Microbiol Rev 2014; 39:134-54. [PMID: 25793961 PMCID: PMC4471445 DOI: 10.1093/femsre/fuu001] [Citation(s) in RCA: 178] [Impact Index Per Article: 17.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Prokaryotes have engineered sophisticated surface nanomachines that have allowed them to colonize Earth and thrive even in extreme environments. Filamentous machineries composed of type IV pilins, which are associated with an amazing array of properties ranging from motility to electric conductance, are arguably the most widespread since distinctive proteins dedicated to their biogenesis are found in most known species of prokaryotes. Several decades of investigations, starting with type IV pili and then a variety of related systems both in bacteria and archaea, have outlined common molecular and structural bases for these nanomachines. Using type IV pili as a paradigm, we will highlight in this review common aspects and key biological differences of this group of filamentous structures. Using type IV pili as a paradigm, we review common genetic, structural and mechanistic features (many) as well as differences (few) of the exceptionally widespread and functionally versatile prokaryotic nano-machines composed of type IV pilins.
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Affiliation(s)
- Jamie-Lee Berry
- MRC Centre for Molecular Bacteriology and Infection, Imperial College London, London SW7 2AZ, UK
| | - Vladimir Pelicic
- MRC Centre for Molecular Bacteriology and Infection, Imperial College London, London SW7 2AZ, UK
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16
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Salzer R, Herzberg M, Nies DH, Joos F, Rathmann B, Thielmann Y, Averhoff B. Zinc and ATP binding of the hexameric AAA-ATPase PilF from Thermus thermophilus: role in complex stability, piliation, adhesion, twitching motility, and natural transformation. J Biol Chem 2014; 289:30343-30354. [PMID: 25202014 DOI: 10.1074/jbc.m114.598656] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
The traffic AAA-ATPase PilF is essential for pilus biogenesis and natural transformation of Thermus thermophilus HB27. Recently, we showed that PilF forms hexameric complexes containing six zinc atoms coordinated by conserved tetracysteine motifs. Here we report that zinc binding is essential for complex stability. However, zinc binding is neither required for pilus biogenesis nor natural transformation. A number of the mutants did not exhibit any pili during growth at 64 °C but still were transformable. This leads to the conclusion that type 4 pili and the DNA translocator are distinct systems. At lower growth temperatures (55 °C) the zinc-depleted multiple cysteine mutants were hyperpiliated but defective in pilus-mediated twitching motility. This provides evidence that zinc binding is essential for the role of PilF in pilus dynamics. Moreover, we found that zinc binding is essential for complex stability but dispensable for ATPase activity. In contrast to many polymerization ATPases from mesophilic bacteria, ATP binding is not required for PilF complex formation; however, it significantly increases complex stability. These data suggest that zinc and ATP binding increase complex stability that is important for functionality of PilF under extreme environmental conditions.
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Affiliation(s)
- Ralf Salzer
- Molecular Microbiology and Bioenergetics, Institute of Molecular Biosciences, Goethe University Frankfurt, 60438 Frankfurt am Main, Germany
| | - Martin Herzberg
- Molecular Microbiology, Institute for Biology/Microbiology, Martin Luther University, 06120 Halle-Wittenberg, Germany
| | - Dietrich H Nies
- Molecular Microbiology, Institute for Biology/Microbiology, Martin Luther University, 06120 Halle-Wittenberg, Germany
| | - Friederike Joos
- Department of Structural Biology, Max Planck Institute of Biophysics, Frankfurt am Main, Germany, and
| | - Barbara Rathmann
- Department of Molecular Membrane Biology, Max Planck Institute of Biophysics, 60438 Frankfurt am Main, Germany
| | - Yvonne Thielmann
- Department of Molecular Membrane Biology, Max Planck Institute of Biophysics, 60438 Frankfurt am Main, Germany
| | - Beate Averhoff
- Molecular Microbiology and Bioenergetics, Institute of Molecular Biosciences, Goethe University Frankfurt, 60438 Frankfurt am Main, Germany,.
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17
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Structure and assembly of an inner membrane platform for initiation of type IV pilus biogenesis. Proc Natl Acad Sci U S A 2013; 110:E4638-47. [PMID: 24218553 DOI: 10.1073/pnas.1312313110] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
Type IV pili are long fibers that are assembled by polymerization of a major pilin protein in the periplasm of a wide range of bacteria and archaea. They play crucial roles in pathogenesis, DNA transformation, and motility, and are capable of rapid retraction, generating powerful motor forces. PilN and PilO are integral inner membrane proteins that are essential for type IV pilus formation. Here, we show that PilN and PilO from Thermus thermophilus can be isolated as a complex with PilM, a cytoplasmic protein with structural similarities to the cytoskeletal protein MreB. The crystal structure of the periplasmic portion of PilN forms a homodimer with an extensive, conserved interaction interface. We conducted serial 3D reconstructions by electron microscopy of PilMN, PilMNO, and PilMNO bound to the major pilin protein PilA4, to chart the assembly of the inner membrane pilus biogenesis platform. PilN drives the dimerization of the PilMN complex with a stoichiometry of 2:2; binding of two PilO monomers then causes the PilN periplasmic domains to dissociate. Finally, two PilA4 monomers bind to the periplasmic domains of PilN and PilO, to generate a T-shaped complex that is primed for addition of the pilin to the nascent pilus fiber. Docking of structures for PilM, PilN, PilO, and PilA4 into the electron density maps of the transmembrane complexes was used to generate a sequence of molecular structures that chart the initial events in type IV pilus formation, and provide structural information on the early events in this important secretion process.
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18
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Type IV pilus biogenesis, twitching motility, and DNA uptake in Thermus thermophilus: discrete roles of antagonistic ATPases PilF, PilT1, and PilT2. Appl Environ Microbiol 2013; 80:644-52. [PMID: 24212586 DOI: 10.1128/aem.03218-13] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Natural transformation has a large impact on lateral gene flow and has contributed significantly to the ecological diversification and adaptation of bacterial species. Thermus thermophilus HB27 has emerged as the leading model organism for studies of DNA transporters in thermophilic bacteria. Recently, we identified a zinc-binding polymerization nucleoside triphosphatase (NTPase), PilF, which is essential for the transport of DNA through the outer membrane. Here, we present genetic evidence that PilF is also essential for the biogenesis of pili. One of the most challenging questions was whether T. thermophilus has any depolymerization NTPase acting as a counterplayer of PilF. We identified two depolymerization NTPases, PilT1 (TTC1621) and PilT2 (TTC1415), both of which are required for type IV pilus (T4P)-mediated twitching motility and adhesion but dispensable for natural transformation. This suggests that T4P dynamics are not required for natural transformation. The latter finding is consistent with our suggestion that in T. thermophilus, T4P and natural transformation are linked but distinct systems.
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Wu WL, Liao JH, Lin GH, Lin MH, Chang YC, Liang SY, Yang FL, Khoo KH, Wu SH. Phosphoproteomic analysis reveals the effects of PilF phosphorylation on type IV pilus and biofilm formation in Thermus thermophilus HB27. Mol Cell Proteomics 2013; 12:2701-13. [PMID: 23828892 DOI: 10.1074/mcp.m113.029330] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Thermus thermophilus HB27 is an extremely thermophilic eubacteria with a high frequency of natural competence. This organism is therefore often used as a thermophilic model to investigate the molecular basis of type IV pili-mediated functions, such as the uptake of free DNA, adhesion, twitching motility, and biofilm formation, in hot environments. In this study, the phosphoproteome of T. thermophilus HB27 was analyzed via a shotgun approach and high-accuracy mass spectrometry. Ninety-three unique phosphopeptides, including 67 in vivo phosphorylated sites on 53 phosphoproteins, were identified. The distribution of Ser/Thr/Tyr phosphorylation sites was 57%/36%/7%. The phosphoproteins were mostly involved in central metabolic pathways and protein/cell envelope biosynthesis. According to this analysis, the ATPase motor PilF, a type IV pili-related component, was first found to be phosphorylated on Thr-368 and Ser-372. Through the point mutation of PilF, mimic phosphorylated mutants T368D and S372E resulted in nonpiliated and nontwitching phenotypes, whereas nonphosphorylated mutants T368V and S372A displayed piliation and twitching motility. In addition, mimic phosphorylated mutants showed elevated biofilm-forming abilities with a higher initial attachment rate, caused by increasing exopolysaccharide production. In summary, the phosphorylation of PilF might regulate the pili and biofilm formation associated with exopolysaccharide production.
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Affiliation(s)
- Wan-Ling Wu
- Institute of Biochemical Sciences, College of Life Sciences, National Taiwan University, Taipei 106, Taiwan
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20
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Salzer R, Herzberg M, Nies DH, Biuković G, Grüber G, Müller V, Averhoff B. The DNA uptake ATPase PilF of Thermus thermophilus: a reexamination of the zinc content. Extremophiles 2013; 17:697-8. [PMID: 23712905 DOI: 10.1007/s00792-013-0544-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2013] [Accepted: 04/29/2013] [Indexed: 10/26/2022]
Abstract
The DNA-translocator ATPase PilF of Thermus thermophilus HB27 is a hexamer built by six identical subunits. Despite the presence of a conserved zinc-binding site in every subunit, only one zinc atom per hexamer was found. Re-examination of the zinc content of PilF purified from cells grown in complex media with different lots of yeast extract revealed six zinc atoms per hexamer. These data demonstrate that the low zinc content reported before was most likely a result of zinc depletion of the yeast extract used.
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Affiliation(s)
- Ralf Salzer
- Molecular Microbiology and Bioenergetics, Institute of Molecular Biosciences, Goethe University Frankfurt, Max-von-Laue-Str. 9, 60438 Frankfurt am Main, Germany
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21
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Abstract
Many Gram-negative bacteria contain specific systems for uptake of foreign DNA, which play a critical role in the acquisition of antibiotic resistance. The TtPilF (PilF ATPase from Thermus thermophilus) is required for high transformation efficiency, but its mechanism of action is unknown. In the present study, we show that TtPilF is able to bind to both DNA and RNA. The structure of TtPilF was determined by cryoelectron microscopy in the presence and absence of the ATP analogue p[NH]ppA (adenosine 5'-[β,γ-imido]triphosphate), at 10 and 12 Å (1 Å=0.1 nm) resolutions respectively. It consists of two distinct N- and C-terminal regions, separated by a short stem-like structure. Binding of p[NH]ppA induces structural changes in the C-terminal domains, which are transmitted via the stem to the N-terminal domains. Molecular models were generated for the apoenzyme and p[NH]ppA-bound states in the C-terminal regions by docking of a model based on a crystal structure from a closely related enzyme. Analysis of DNA binding by electron microscopy, using gold labelling, localized the binding site to the N-terminal domains. The results suggest a model in which DNA uptake by TtPilF is powered by ATP hydrolysis, causing conformational changes in the C-terminal domains, which are transmitted via the stem to take up DNA into the cell.
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22
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Burkhardt J, Vonck J, Langer JD, Salzer R, Averhoff B. Unusual N-terminal ααβαββα fold of PilQ from Thermus thermophilus mediates ring formation and is essential for piliation. J Biol Chem 2012; 287:8484-94. [PMID: 22253437 DOI: 10.1074/jbc.m111.334912] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
DNA translocators of natural transformation systems are complex systems critical for the uptake of free DNA and provide a powerful mechanism for adaptation to changing environmental conditions. In natural transformation machineries, outer membrane secretins are suggested to form a multimeric pore for the uptake of external DNA. Recently, we reported on a novel structure of the DNA translocator secretin complex, PilQ, in Thermus thermophilus HB27 comprising a stable cone and cup structure and six ring structures with a large central channel. Here, we report on structural and functional analyses of a set of N-terminal PilQ deletion derivatives in T. thermophilus HB27. We identified 136 N-terminal residues exhibiting an unusual ααβαββα fold as a ring-building domain. Deletion of this domain had a dramatic effect on twitching motility, adhesion, and piliation but did not abolish natural transformation. These findings provide clear evidence that the pilus structures of T. thermophilus are not essential for natural transformation. The truncated complex was not affected in inner and outer membrane association, indicating that the 136 N-terminal residues are not essential for membrane targeting. Analyses of complex formation of the truncated PilQ monomers revealed that the region downstream of residue 136 is required for multimerization, and the region downstream of residue 207 is essential for monomer stability. Possible implications of our findings for the mechanism of DNA uptake are discussed.
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Affiliation(s)
- Janin Burkhardt
- Molecular Microbiology and Bioenergetics, Institute of Molecular Biosciences, Goethe University, Max-von-Laue-Strasse 9, D-60438 Frankfurt/Main, Germany
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23
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Burkhardt J, Vonck J, Averhoff B. Structure and function of PilQ, a secretin of the DNA transporter from the thermophilic bacterium Thermus thermophilus HB27. J Biol Chem 2011; 286:9977-84. [PMID: 21285351 DOI: 10.1074/jbc.m110.212688] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Secretins are a family of large bacterial outer membrane protein complexes mediating the transport of complex structures, such as type IV pili, DNA and filamentous phage, or various proteins, such as extracellular enzymes and pathogenicity determinants. PilQ of the thermophilic bacterium Thermus thermophilus HB27 is a member of the secretin family required for natural transformation. Here we report the isolation, structural, and functional analyses of a unique PilQ from T. thermophilus. Native PAGE, gel filtration chromatography, and electrophoretic mobility shift analyses indicated that PilQ forms a macromolecular homopolymeric complex that binds dsDNA. Electron microscopy showed that the PilQ complex is 15 nm wide and 34 nm long and consists of an extraordinary stable "cone" and "cup" structure and five ring structures with a large central channel. Moreover, the electron microscopic images together with secondary structure analyses combined with structural data of type II protein secretion system and type III protein secretion system secretins suggest that the individual rings are formed by conserved domains of alternating α-helices and β-sheets. The unprecedented length of the PilQ complex correlated well with the distance between the inner and outer membrane of T. thermophilus. Indeed, PilQ was found immunologically in both membranes, indicating that the PilQ complex spans the entire cell periphery of T. thermophilus. This is consistent with the hypothesis that PilQ accommodates a PilA4 comprising pseudopilus mediating DNA transport across the outer membrane and periplasmic space in a single-step process.
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Affiliation(s)
- Janin Burkhardt
- Molecular Microbiology and Bioenergetics, Institute of Molecular Biosciences, Goethe University, Max-von-Laue-Strasse 9, D-60438 Frankfurt/Main, Germany
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