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Song W, Zhang S, Majzoub ME, Egan S, Kjelleberg S, Thomas T. The impact of interspecific competition on the genomic evolution of Phaeobacter inhibens and Pseudoalteromonas tunicata during biofilm growth. Environ Microbiol 2024; 26:e16553. [PMID: 38062568 DOI: 10.1111/1462-2920.16553] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2023] [Accepted: 11/24/2023] [Indexed: 01/30/2024]
Abstract
Interspecific interactions in biofilms have been shown to cause the emergence of community-level properties. To understand the impact of interspecific competition on evolution, we deep-sequenced the dispersal population of mono- and co-culture biofilms of two antagonistic marine bacteria (Phaeobacter inhibens 2.10 and Pseudoalteromononas tunicata D2). Enhanced phenotypic and genomic diversification was observed in the P. tunicata D2 populations under both mono- and co-culture biofilms in comparison to P. inhibens 2.10. The genetic variation was exclusively due to single nucleotide variants and small deletions, and showed high variability between replicates, indicating their random emergence. Interspecific competition exerted an apparent strong positive selection on a subset of P. inhibens 2.10 genes (e.g., luxR, cobC, argH, and sinR) that could facilitate competition, while the P. tunicata D2 population was genetically constrained under competition conditions. In the absence of interspecific competition, the P. tunicata D2 replicate populations displayed high levels of mutations affecting the same genes involved in cell motility and biofilm formation. Our results show that interspecific biofilm competition has a complex impact on genomic diversification, which likely depends on the nature of the competing strains and their ability to generate genetic variants due to their genomic constraints.
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Affiliation(s)
- Weizhi Song
- Centre for Marine Science and Innovation, School of Biological, Earth and Environmental Sciences, Faculty of Science, The University of New South Wales, Kensington, New South Wales, Australia
- School of Biological, Earth and Environmental Sciences, University of New South Wales, Kensington, New South Wales, Australia
| | - Shan Zhang
- Centre for Marine Science and Innovation, School of Biological, Earth and Environmental Sciences, Faculty of Science, The University of New South Wales, Kensington, New South Wales, Australia
- School of Biological, Earth and Environmental Sciences, University of New South Wales, Kensington, New South Wales, Australia
| | - Marwan E Majzoub
- Centre for Marine Science and Innovation, School of Biological, Earth and Environmental Sciences, Faculty of Science, The University of New South Wales, Kensington, New South Wales, Australia
- School of Biological, Earth and Environmental Sciences, University of New South Wales, Kensington, New South Wales, Australia
| | - Suhelen Egan
- Centre for Marine Science and Innovation, School of Biological, Earth and Environmental Sciences, Faculty of Science, The University of New South Wales, Kensington, New South Wales, Australia
- School of Biological, Earth and Environmental Sciences, University of New South Wales, Kensington, New South Wales, Australia
| | - Staffan Kjelleberg
- Centre for Marine Science and Innovation, School of Biological, Earth and Environmental Sciences, Faculty of Science, The University of New South Wales, Kensington, New South Wales, Australia
- School of Biological, Earth and Environmental Sciences, University of New South Wales, Kensington, New South Wales, Australia
- Singapore Centre for Environmental Life Sciences Engineering, Nanyang Technological University, Singapore, Singapore
- School of Biological Sciences, Nanyang Technological University, Singapore, Singapore
| | - Torsten Thomas
- Centre for Marine Science and Innovation, School of Biological, Earth and Environmental Sciences, Faculty of Science, The University of New South Wales, Kensington, New South Wales, Australia
- School of Biological, Earth and Environmental Sciences, University of New South Wales, Kensington, New South Wales, Australia
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Dupuy P, Glickman MS. The C-Terminal Acid Phosphatase Module of the RNase HI Enzyme RnhC Controls Rifampin Sensitivity and Light-Dependent Colony Pigmentation of Mycobacterium smegmatis. J Bacteriol 2023; 205:e0043122. [PMID: 36916909 PMCID: PMC10127661 DOI: 10.1128/jb.00431-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2022] [Accepted: 02/16/2023] [Indexed: 03/16/2023] Open
Abstract
RNase H enzymes participate in various processes that require processing of RNA-DNA hybrids, including DNA replication, transcription, and ribonucleotide excision from DNA. Mycobacteria encode multiple RNase H enzymes, and prior data indicate that RNase HI activity is essential for mycobacterial viability. However, the additional roles of mycobacterial RNase Hs are unknown, including whether RNase HII (RnhB and RnhD) excises chromosomal ribonucleotides misincorporated during DNA replication and whether individual RNase HI enzymes (RnhA and RnhC) mediate additional phenotypes. We find that loss of RNase HII activity in Mycobacterium smegmatis (through combined deletion of rnhB/rnhD) or individual RNase HI enzymes does not affect growth, hydroxyurea sensitivity, or mutagenesis, whereas overexpression (OE) of either RNase HII severely compromises bacterial viability. We also show that deletion of rnhC, which encodes a protein with an N-terminal RNase HI domain and a C-terminal acid phosphatase domain, confers sensitivity to rifampin and oxidative stress as well as loss of light-induced carotenoid pigmentation. These phenotypes are due to loss of the activity of the C-terminal acid phosphatase domain rather than the RNase HI activity, suggesting that the acid phosphatase activity may confer rifampin resistance through the antioxidant properties of carotenoid pigment production. IMPORTANCE Mycobacteria encode multiple RNase H enzymes, with RNase HI being essential for viability. Here, we examine additional functions of RNase H enzymes in mycobacteria. We find that RNase HII is not involved in mutagenesis but is highly toxic when overexpressed. The RNase HI enzyme RnhC is required for tolerance to rifampin, but this role is surprisingly independent of its RNase H activity and is instead mediated by an autonomous C-terminal acid phosphatase domain. This study provides new insights into the functions of the multiple RNase H enzymes of mycobacteria.
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Affiliation(s)
- Pierre Dupuy
- Immunology Program, Sloan Kettering Institute, New York, New York, USA
| | - Michael S. Glickman
- Immunology Program, Sloan Kettering Institute, New York, New York, USA
- Immunology and Microbial Pathogenesis Graduate Program, Weill Cornell Graduate School, New York, New York, USA
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RNase HI Depletion Strongly Potentiates Cell Killing by Rifampicin in Mycobacteria. Antimicrob Agents Chemother 2022; 66:e0209121. [PMID: 36154174 DOI: 10.1128/aac.02091-21] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Multidrug-resistant (MDR) tuberculosis (TB) is defined by the resistance of Mycobacterium tuberculosis, the causative organism, to the first-line antibiotics rifampicin and isoniazid. Mitigating or reversing resistance to these drugs offers a means of preserving and extending their use in TB treatment. R-loops are RNA/DNA hybrids that are formed in the genome during transcription, and they can be lethal to the cell if not resolved. RNase HI is an enzyme that removes R-loops, and this activity is essential in M. tuberculosis: knockouts of rnhC, the gene encoding RNase HI, are nonviable. This essentiality makes it a candidate target for the development of new antibiotics. In the model organism Mycolicibacterium smegmatis, RNase HI activity is provided by two enzymes, RnhA and RnhC. We show that the partial depletion of RNase HI activity in M. smegmatis, by knocking out either of the genes encoding RnhA or RnhC, led to the accumulation of R-loops. The sensitivity of the knockout strains to the antibiotics moxifloxacin, streptomycin, and rifampicin was increased, the latter by a striking near 100-fold. We also show that R-loop accumulation accompanies partial transcriptional inhibition, suggesting a mechanistic basis for the synergy between RNase HI depletion and rifampicin. A model of how transcriptional inhibition can potentiate R-loop accumulation is presented. Finally, we identified four small molecules that inhibit recombinant RnhC activity and that also potentiated rifampicin activity in whole-cell assays against M. tuberculosis, supporting an on-target mode of action and providing the first step in developing a new class of antimycobacterial drug.
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Reed CJ, Hutinet G, de Crécy-Lagard V. Comparative Genomic Analysis of the DUF34 Protein Family Suggests Role as a Metal Ion Chaperone or Insertase. Biomolecules 2021; 11:1282. [PMID: 34572495 PMCID: PMC8469502 DOI: 10.3390/biom11091282] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2021] [Revised: 08/20/2021] [Accepted: 08/24/2021] [Indexed: 12/12/2022] Open
Abstract
Members of the DUF34 (domain of unknown function 34) family, also known as the NIF3 protein superfamily, are ubiquitous across superkingdoms. Proteins of this family have been widely annotated as "GTP cyclohydrolase I type 2" through electronic propagation based on one study. Here, the annotation status of this protein family was examined through a comprehensive literature review and integrative bioinformatic analyses that revealed varied pleiotropic associations and phenotypes. This analysis combined with functional complementation studies strongly challenges the current annotation and suggests that DUF34 family members may serve as metal ion insertases, chaperones, or metallocofactor maturases. This general molecular function could explain how DUF34 subgroups participate in highly diversified pathways such as cell differentiation, metal ion homeostasis, pathogen virulence, redox, and universal stress responses.
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Affiliation(s)
- Colbie J. Reed
- Department of Microbiology and Cell Science, University of Florida, Gainesville, FL 32611, USA; (C.J.R.); (G.H.)
| | - Geoffrey Hutinet
- Department of Microbiology and Cell Science, University of Florida, Gainesville, FL 32611, USA; (C.J.R.); (G.H.)
| | - Valérie de Crécy-Lagard
- Department of Microbiology and Cell Science, University of Florida, Gainesville, FL 32611, USA; (C.J.R.); (G.H.)
- Genetics Institute, University of Florida, Gainesville, FL 32611, USA
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Cobalamin is present in cells of non-tuberculous mycobacteria, but not in Mycobacterium tuberculosis. Sci Rep 2021; 11:12267. [PMID: 34112827 PMCID: PMC8192938 DOI: 10.1038/s41598-021-91430-w] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2021] [Accepted: 05/26/2021] [Indexed: 01/22/2023] Open
Abstract
Cobalamin (vitamin B12) is a structurally complex molecule that acts as a cofactor for enzymes and regulates gene expression through so-called riboswitches. The existing literature on the vitamin B12 synthesis capacity in Mycobacterium tuberculosis is ambiguous, while in non-tuberculous mycobacteria (NTM) is rather marginal. Here we present the results of our investigation into the occurrence of vitamin B12 in mycobacteria. For detection purposes, immunoassay methods were applied to cell lysates of NTM and M. tuberculosis clinical and laboratory strains grown under different conditions. We show that whereas vitamin B12 is present in cells of various NTM species, it cannot be evidenced in strains of differently cultured M. tuberculosis, even though the genes responsible for vitamin B12 synthesis are actively expressed based on RNA-Seq data. In summary, we conclude that the production of vitamin B12 does occur in mycobacteria, with the likely exception of M. tuberculosis. Our results provide direct evidence of vitamin B12 synthesis in a clinically important group of bacteria.
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