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Schons-Fonseca L, Lazova MD, Smith JL, Anderson ME, Grossman AD. Beneficial and detrimental genes in the cellular response to replication arrest. PLoS Genet 2022; 18:e1010564. [PMID: 36574412 PMCID: PMC9836290 DOI: 10.1371/journal.pgen.1010564] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2021] [Revised: 01/12/2023] [Accepted: 12/09/2022] [Indexed: 12/28/2022] Open
Abstract
DNA replication is essential for all living organisms. Several events can disrupt replication, including DNA damage (e.g., pyrimidine dimers, crosslinking) and so-called "roadblocks" (e.g., DNA-binding proteins or transcription). Bacteria have several well-characterized mechanisms for repairing damaged DNA and then restoring functional replication forks. However, little is known about the repair of stalled or arrested replication forks in the absence of chemical alterations to DNA. Using a library of random transposon insertions in Bacillus subtilis, we identified 35 genes that affect the ability of cells to survive exposure to an inhibitor that arrests replication elongation, but does not cause chemical alteration of the DNA. Genes identified include those involved in iron-sulfur homeostasis, cell envelope biogenesis, and DNA repair and recombination. In B. subtilis, and many bacteria, two nucleases (AddAB and RecJ) are involved in early steps in repairing replication forks arrested by chemical damage to DNA and loss of either nuclease causes increased sensitivity to DNA damaging agents. These nucleases resect DNA ends, leading to assembly of the recombinase RecA onto the single-stranded DNA. Notably, we found that disruption of recJ increased survival of cells following replication arrest, indicating that in the absence of chemical damage to DNA, RecJ is detrimental to survival. In contrast, and as expected, disruption of addA decreased survival of cells following replication arrest, indicating that AddA promotes survival. The different phenotypes of addA and recJ mutants appeared to be due to differences in assembly of RecA onto DNA. RecJ appeared to promote too much assembly of RecA filaments. Our results indicate that in the absence of chemical damage to DNA, RecA is dispensable for cells to survive replication arrest and that the stable RecA nucleofilaments favored by the RecJ pathway may lead to cell death by preventing proper processing of the arrested replication fork.
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Affiliation(s)
- Luciane Schons-Fonseca
- Department of Biology Massachusetts Institute of Technology Cambridge, Massachusetts, United States of America
| | - Milena D. Lazova
- Department of Biology Massachusetts Institute of Technology Cambridge, Massachusetts, United States of America
| | - Janet L. Smith
- Department of Biology Massachusetts Institute of Technology Cambridge, Massachusetts, United States of America
| | - Mary E. Anderson
- Department of Biology Massachusetts Institute of Technology Cambridge, Massachusetts, United States of America
| | - Alan D. Grossman
- Department of Biology Massachusetts Institute of Technology Cambridge, Massachusetts, United States of America
- * E-mail:
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Yang C, Wu R, Liu H, Chen Y, Gao Y, Chen X, Li Y, Ma J, Li J, Gan J. Structural insights into DNA degradation by human mitochondrial nuclease MGME1. Nucleic Acids Res 2019; 46:11075-11088. [PMID: 30247721 PMCID: PMC6237815 DOI: 10.1093/nar/gky855] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2018] [Accepted: 09/11/2018] [Indexed: 01/16/2023] Open
Abstract
Mitochondrial nucleases play important roles in accurate maintenance and correct metabolism of mtDNA, the own genetic materials of mitochondria that are passed exclusively from mother to child. MGME1 is a highly conserved DNase that was discovered recently. Mutations in MGME1-coding gene lead to severe mitochondrial syndromes characterized by external ophthalmoplegia, emaciation, and respiratory failure in humans. Unlike many other nucleases that are distributed in multiple cellular organelles, human MGME1 is a mitochondria-specific nuclease; therefore, it can serve as an ideal target for treating related syndromes. Here, we report one HsMGME1-Mn2+ complex and three different HsMGME1-DNA complex structures. In combination with in vitro cleavage assays, our structures reveal the detailed molecular basis for substrate DNA binding and/or unwinding by HsMGME1. Besides the conserved two-cation-assisted catalytic mechanism, structural analysis of HsMGME1 and comparison with homologous proteins also clarified substrate binding and cleavage directionalities of the DNA double-strand break repair complexes RecBCD and AddAB.
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Affiliation(s)
- Chun Yang
- State Key Laboratory of Genetic Engineering, Collaborative Innovation Center of Genetics and Development, Department of Physiology and Biophysics, School of Life Sciences, Fudan University, Shanghai 200433, China
| | - Ruiqi Wu
- State Key Laboratory of Genetic Engineering, Collaborative Innovation Center of Genetics and Development, Department of Physiology and Biophysics, School of Life Sciences, Fudan University, Shanghai 200433, China
| | - Hehua Liu
- State Key Laboratory of Genetic Engineering, Collaborative Innovation Center of Genetics and Development, Department of Physiology and Biophysics, School of Life Sciences, Fudan University, Shanghai 200433, China.,State Key Laboratory of Genetic Engineering, Collaborative Innovation Center of Genetics and Development, Department of Biochemistry, School of Life Sciences, Fudan University, Shanghai 200433, China
| | - Yiqing Chen
- State Key Laboratory of Genetic Engineering, Collaborative Innovation Center of Genetics and Development, Department of Physiology and Biophysics, School of Life Sciences, Fudan University, Shanghai 200433, China
| | - Yanqing Gao
- State Key Laboratory of Genetic Engineering, Collaborative Innovation Center of Genetics and Development, Department of Physiology and Biophysics, School of Life Sciences, Fudan University, Shanghai 200433, China
| | - Xi Chen
- State Key Laboratory of Genetic Engineering, Collaborative Innovation Center of Genetics and Development, Department of Physiology and Biophysics, School of Life Sciences, Fudan University, Shanghai 200433, China
| | - Yangyang Li
- State Key Laboratory of Genetic Engineering, Collaborative Innovation Center of Genetics and Development, Department of Physiology and Biophysics, School of Life Sciences, Fudan University, Shanghai 200433, China
| | - Jinbiao Ma
- State Key Laboratory of Genetic Engineering, Collaborative Innovation Center of Genetics and Development, Department of Biochemistry, School of Life Sciences, Fudan University, Shanghai 200433, China
| | - Jixi Li
- State Key Laboratory of Genetic Engineering, Collaborative Innovation Center of Genetics and Development, Department of Physiology and Biophysics, School of Life Sciences, Fudan University, Shanghai 200433, China.,Department of Neurology, Huashan Hospital, Fudan University, Shanghai 200040, China
| | - Jianhua Gan
- State Key Laboratory of Genetic Engineering, Collaborative Innovation Center of Genetics and Development, Department of Physiology and Biophysics, School of Life Sciences, Fudan University, Shanghai 200433, China
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Dunn KL, Rao CV. High-throughput sequencing reveals adaptation-induced mutations in pentose-fermenting strains ofZymomonas mobilis. Biotechnol Bioeng 2015; 112:2228-40. [DOI: 10.1002/bit.25631] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2015] [Revised: 03/22/2015] [Accepted: 04/29/2015] [Indexed: 11/09/2022]
Affiliation(s)
- Kori L. Dunn
- Department of Chemical and Biomolecular Engineering; University of Illinois at Urbana-Champaign; Urbana Illinois 61801
| | - Christopher V. Rao
- Department of Chemical and Biomolecular Engineering; University of Illinois at Urbana-Champaign; Urbana Illinois 61801
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Abstract
From microbes to multicellular eukaryotic organisms, all cells contain pathways responsible for genome maintenance. DNA replication allows for the faithful duplication of the genome, whereas DNA repair pathways preserve DNA integrity in response to damage originating from endogenous and exogenous sources. The basic pathways important for DNA replication and repair are often conserved throughout biology. In bacteria, high-fidelity repair is balanced with low-fidelity repair and mutagenesis. Such a balance is important for maintaining viability while providing an opportunity for the advantageous selection of mutations when faced with a changing environment. Over the last decade, studies of DNA repair pathways in bacteria have demonstrated considerable differences between Gram-positive and Gram-negative organisms. Here we review and discuss the DNA repair, genome maintenance, and DNA damage checkpoint pathways of the Gram-positive bacterium Bacillus subtilis. We present their molecular mechanisms and compare the functions and regulation of several pathways with known information on other organisms. We also discuss DNA repair during different growth phases and the developmental program of sporulation. In summary, we present a review of the function, regulation, and molecular mechanisms of DNA repair and mutagenesis in Gram-positive bacteria, with a strong emphasis on B. subtilis.
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Meima R, Eschevins C, Fillinger S, Bolhuis A, Hamoen LW, Dorenbos R, Quax WJ, van Dijl JM, Provvedi R, Chen I, Dubnau D, Bron S. The bdbDC operon of Bacillus subtilis encodes thiol-disulfide oxidoreductases required for competence development. J Biol Chem 2002; 277:6994-7001. [PMID: 11744713 DOI: 10.1074/jbc.m111380200] [Citation(s) in RCA: 79] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The development of genetic competence in the Gram-positive eubacterium Bacillus subtilis is a complex postexponential process. Here we describe a new bicistronic operon, bdbDC, required for competence development, which was identified by the B. subtilis Systematic Gene Function Analysis program. Inactivation of either the bdbC or bdbD genes of this operon results in the loss of transformability without affecting recombination or the synthesis of ComK, the competence transcription factor. BdbC and BdbD are orthologs of enzymes known to be involved in extracytoplasmic disulfide bond formation. Consistent with this, BdbC and BdbD are needed for the secretion of the Escherichia coli disulfide bond-containing alkaline phosphatase, PhoA, by B. subtilis. Similarly, the amount of the disulfide bond-containing competence protein ComGC is severely reduced in bdbC or bdbD mutants. In contrast, the amounts of the competence proteins ComGA and ComEA remain unaffected by bdbDC mutations. Taken together, these observations imply that in the absence of either BdbC or BdbD, ComGC is unstable and that BdbC and BdbD catalyze the formation of disulfide bonds that are essential for the DNA binding and uptake machinery.
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Affiliation(s)
- Rob Meima
- Groningen Biomolecular Sciences and Biotechnology Institute, Department of Genetics, University of Groningen, Kerklaan 30, 9751 NN Haren, The Netherlands
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Chédin F, Noirot P, Biaudet V, Ehrlich SD. A five-nucleotide sequence protects DNA from exonucleolytic degradation by AddAB, the RecBCD analogue of Bacillus subtilis. Mol Microbiol 1998; 29:1369-77. [PMID: 9781875 DOI: 10.1046/j.1365-2958.1998.01018.x] [Citation(s) in RCA: 60] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Homologous recombination in Bacillus subtilis requires the product of the addA and addB genes, the AddAB enzyme. This enzyme, which is both a helicase and a powerful nuclease, is thought to be the counterpart of the Escherichia coli RecBCD enzyme. From this analogy, it is expected that the nuclease activity of AddAB can be downregulated by a specific DNA sequence, which would correspond to the chi site in E. coli. Using protection of linear double-stranded DNA as a criterion, we identified the five-nucleotide sequence 5'-AGCGG-3', or its complement 5'-CCGCT-3', as being sufficient for AddAB nuclease attenuation. We have shown further that this attenuation occurs only if the sequence is properly oriented with respect to the translocating AddAB enzyme. Finally, inspection of the complete B. subtilis genome revealed that this five-nucleotide sequence is over-represented and is, in a majority of cases, co-oriented with DNA replication. Based on these observations, we propose that 5'-AGCGG-3', or its complement, is the B. subtilis analogue of the E. coli chi sequence.
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Affiliation(s)
- F Chédin
- Laboratoire de Génétique Microbienne, Institut National de Recherche Agronomique, Domaine de Vilvert, Jouy en Josas, France
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Meima R, Haan GJ, Venema G, Bron S, de Jong S. Sequence specificity of illegitimate plasmid recombination in Bacillus subtilis: possible recognition sites for DNA topoisomerase I. Nucleic Acids Res 1998; 26:2366-73. [PMID: 9580687 PMCID: PMC147579 DOI: 10.1093/nar/26.10.2366] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Previous work in our group indicated that structural plasmid instability in Bacillus subtilis is often caused by illegitimate recombination between non-repeated sequences, characterized by a relatively high AT content. Recently we developed a positive selection vector for analysis of plasmid recombination events in B. subtilis which enables measurement of recombination frequencies without interference of selective growth differences of cells carrying wild-type or deleted plasmids. Here we have used this system to further analyse the sequence specificity of illegitimate plasmid recombination events and to assess the role of the host-encoded DNA topoisomerase I enzyme in this process. Several lines of evidence suggest that single-strand DNA nicks introduced by DNA topoisomerase I are a major source of plasmid deletions in pGP100. First, strains overproducing DNA topoisomerase I showed increased levels of plasmid deletion. Second, these deletions occurred predominantly (>90% of the recombinants) between non-repeated DNA sequences, the majority of which resemble potential DNA topoisomerase I target sites. Sequence alignment of 66 deletion end-points confirmed the previously reported high AT content and, most importantly, revealed a highly conserved C residue at position -4 relative to the site of cleavage at both deletion termini. Based on these genetic data we propose the following putative consensus cleavage site for DNA topoisomerase I of B.subtilis: 5'-A/TCATA/TTAA/TA/TA-3'.
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Affiliation(s)
- R Meima
- Department of Genetics, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Kerklaan 30, 9751 NN Haren, The Netherlands
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Meima R, Haijema BJ, Dijkstra H, Haan GJ, Venema G, Bron S. Role of enzymes of homologous recombination in illegitimate plasmid recombination in Bacillus subtilis. J Bacteriol 1997; 179:1219-29. [PMID: 9023205 PMCID: PMC178819 DOI: 10.1128/jb.179.4.1219-1229.1997] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
The structural stability of plasmid pGP1, which encodes a fusion between the penicillinase gene (penP) of Bacillus licheniformis and the Escherichia coli lacZ gene, was investigated in Bacillus subtilis strains expressing mutated subunits of the ATP-dependent nuclease, AddAB, and strains lacking the major recombination enzyme, RecA. Strains carrying a mutation in the ATP-binding site of the AddB subunit exhibited high levels of plasmid instability, whereas a comparable mutation in the A subunit did not affect plasmid stability. Using an alternative plasmid system, pGP100, we were able to demonstrate that the differences in stability reflected differences in initial recombination frequencies. Based on a comparison of endpoint sequences observed in the various hosts, we speculate that at least two different mechanisms underlie the deletion events involved, the first (type I) occurring between nonrepeated sequences, and the second (type II) occurring between short direct repeats (DRs). The latter event was independent of single-strand replication intermediates and the mode of replication and possibly requires the introduction of double-strand breaks (DSBs) between the repeats. In the absence of functional AddAB complex, or the AddB subunit, DSBs are likely to be processed via a recA-independent mechanism, resulting in intramolecular recombination between the DRs. In wild-type cells, such DSBs are supposed to be either repaired by a mechanism involving AddAB-dependent recombination or degraded by the AddAB-associated exonuclease activity. Plasmid stability assays in a recA mutant showed that (i) the level of deletion formation was considerably higher in this host and (ii) that deletions between short DRs occurred at higher frequencies than those described previously for the parental strain. We propose that in wild-type cells, the recA gene product is involved in recombinational repair of DSBs.
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Affiliation(s)
- R Meima
- Department of Genetics, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Haren, The Netherlands
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Cordes C, Meima R, Twiest B, Kazemier B, Venema G, van Dijl JM, Bron S. The expression of a plasmid-specified exported protein causes structural plasmid instability in Bacillus subtilis. J Bacteriol 1996; 178:5235-42. [PMID: 8752343 PMCID: PMC178322 DOI: 10.1128/jb.178.17.5235-5242.1996] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
The rolling-circle plasmid pGP1 was used to study the effects of the expression of a plasmid-specified exported protein on structural plasmid stability in Bacillus subtilis. pGP1 contains a fusion between the Bacillus licheniformis penP gene, encoding a C-terminally truncated penicillinase, and the Escherichia coli beta-galactosidase (lacZ) gene. Two processes affected the accumulation of pGP1 variants with deletions in the penP-lacZ region. First, divergent transcription from genes upstream of penP-lacZ increased pGP1 deletion frequencies up to about 10-fold. Second, the removal of the PenP signal peptide resulted in completely stable plasmids, indicating that the entry of the PenP fragment into the protein export pathway is an important factor in the instability of pGP1. On the basis of these results, we propose a model in which the temporary anchoring of the plasmid to the membrane through the cotranscriptional and cotranslational entry of PenP into the protein export pathway creates domains of local hypersupercoiling, which we assume to be targets for deletion formation.
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Affiliation(s)
- C Cordes
- Department of Genetics, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, The Netherlands
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10
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Haijema BJ, Meima R, Kooistra J, Venema G. Effects of lysine-to-glycine mutations in the ATP-binding consensus sequences in the AddA and AddB subunits on the Bacillus subtilis AddAB enzyme activities. J Bacteriol 1996; 178:5130-7. [PMID: 8752329 PMCID: PMC178308 DOI: 10.1128/jb.178.17.5130-5137.1996] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
The N-terminal regions of both subunits AddA and AddB of the Bacillus subtilis AddAB enzyme contain amino acid sequences, designated motif I, which are commonly found in ATP-binding enzymes. The functional significance of the motif I regions was studied by replacing the highly conserved lysine residues of the regions in both subunits by glycines and by examination of the resulting mutant enzymes with respect to their enzymatic properties. This study shows that the mutation in subunit AddB hardly affected the ATPase, helicase, and exonuclease activities of the AddAB enzyme. However, the mutation in subunit AddA drastically reduced these activities, as well as the kcat for ATP hydrolysis. The apparent Km for ATP in ATP hydrolysis did not significantly deviate from that of the wild-type enzyme. These results suggest that the lysine residue in motif I of subunit AddA of the AddAB enzyme is not essential for the binding of the nucleotide but has a role in ATP hydrolysis, which is required for the exonuclease and helicase activities of the enzyme.
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Affiliation(s)
- B J Haijema
- Department of Genetics, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, The Netherlands
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Haijema BJ, Venema G, Kooistra J. The C terminus of the AddA subunit of the Bacillus subtilis ATP-dependent DNase is required for the ATP-dependent exonuclease activity but not for the helicase activity. J Bacteriol 1996; 178:5086-91. [PMID: 8752323 PMCID: PMC178302 DOI: 10.1128/jb.178.17.5086-5091.1996] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Comparison of subunit AddA of the Bacillus subtilis AddAB enzyme, subunit RecB of the Escherichia coli RecBCD enzyme, and subunit RecB of the Haemophilus influenzae RecBCD enzyme revealed several regions of homology. Whereas the first seven regions are common among helicases, the two C-terminally located regions are unique for RecB of E. coli and H. influenzae and AddA. Deletion of the C-terminal region resulted in the production of an enzyme which showed moderately impaired levels of ATP-dependent helicase activity, whereas the ATP-dependent exonuclease activity was completely destroyed. The mutant enzyme was almost completely capable of complementing E. coli recBCD and B. subtilis addAB strains with respect to DNA repair and homologous recombination. These results strongly suggest that at least part of the C-terminal region of the AddA protein is indispensable for exonuclease activity and that, in contrast to the exonuclease activity, the helicase activity of the addAB gene product is important for DNA repair and homologous recombination.
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Affiliation(s)
- B J Haijema
- Department of Genetics, Biomolecular Sciences and Biotechnology Institute, University of Groningen, The Netherlands
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