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Ochora DO, Mogire RM, Masai RJ, Yeda RA, Mwakio EW, Amwoma JG, Wakoli DM, Yenesew A, Akala HM. Ex vivo and In vitro antiplasmodial activities of approved drugs predicted to have antimalarial activities using chemogenomics and drug repositioning approach. Heliyon 2023; 9:e18863. [PMID: 37583763 PMCID: PMC10424068 DOI: 10.1016/j.heliyon.2023.e18863] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2023] [Revised: 07/31/2023] [Accepted: 07/31/2023] [Indexed: 08/17/2023] Open
Abstract
High malaria mortality coupled with increased emergence of resistant multi-drug resistant strains of Plasmodium parasite, warrants the development of new and effective antimalarial drugs. However, drug design and discovery are costly and time-consuming with many active antimalarial compounds failing to get approved due to safety reasons. To address these challenges, the current study aimed at testing the antiplasmodial activities of approved drugs that were predicted using a target-similarity approach. This approach is based on the fact that if an approved drug used to treat another disease targets a protein similar to Plasmodium falciparum protein, then the drug will have a comparable effect on P. falciparum. In a previous study, in vitro antiplasmodial activities of 10 approved drugs was reported of the total 28 approved drugs. In this study, six out of 18 drugs that were previously not tested, namely epirubicin, irinotecan, venlafaxine, palbociclib, pelitinib, and PD153035 were tested for antiplasmodial activity. The drug susceptibility in vitro assays against five P. falciparum reference strains (D6, 3D7, W2, DD2, and F32 ART) and ex vivo assays against fresh clinical isolates were done using the malaria SYBR Green I assay. Standard antimalarial drugs were included as controls. Epirubicin and irinotecan showed excellent antiplasmodial ex vivo activity against field isolates with mean IC50 values of 0.044 ± 0.033 μM and 0.085 ± 0.055 μM, respectively. Similar activity was observed against W2 strain where epirubicin had an IC50 value of 0.004 ± 0.0009 μM, palbociclib 0.056 ± 0.006 μM, and pelinitib 0.057 ± 0.013 μM. For the DD2 strain, epirubicin, irinotecan and PD 153035 displayed potent antiplasmodial activity (IC50 < 1 μM). Epirubicin and irinotecan showed potent antiplasmodial activities (IC50 < 1 μM) against DD2, D6, 3D7, and F32 ART strains and field isolates. This shows the potential use of these drugs as antimalarials. All the tested drugs showed antiplasmodial activities with IC50 values below 20 μM, which suggests that our target similarity-based strategy is successful at predicting antiplasmodial activity of compounds thereby circumventing challenges in antimalarial drug discovery.
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Affiliation(s)
- Douglas O. Ochora
- Department of Biological Sciences, School of Pure and Applied Sciences, Kisii University, P.O. Box 408-40200, Kisii, Kenya
- DSI/NWU, Preclinical Drug Development Platform, Faculty of Health Sciences, North-West University, Private Bag X6001, 2520, Potchefstroom, South Africa
- United States Army Medical Research Directorate-Africa (USAMRD-A), Kenya Medical Research Institute (KEMRI)—Walter Reed Project, P.O. Box 54-40100, Kisumu, Kenya
| | - Reagan M. Mogire
- Kenya Medical Research Institute (KEMRI) – Kemri-Wellcome Trust Research Programme, P.O. Box 230-80108, Kilifi, Kenya
| | - Rael J. Masai
- Department of Biological Sciences, School of Pure and Applied Sciences, Kisii University, P.O. Box 408-40200, Kisii, Kenya
| | - Redemptah A. Yeda
- United States Army Medical Research Directorate-Africa (USAMRD-A), Kenya Medical Research Institute (KEMRI)—Walter Reed Project, P.O. Box 54-40100, Kisumu, Kenya
| | - Edwin W. Mwakio
- United States Army Medical Research Directorate-Africa (USAMRD-A), Kenya Medical Research Institute (KEMRI)—Walter Reed Project, P.O. Box 54-40100, Kisumu, Kenya
| | - Joseph G. Amwoma
- Department of Biological Sciences, University of Embu P. O. Box 6-60100, Embu, Kenya
| | - Dancan M. Wakoli
- Department of Biochemistry and Molecular Biology, Egerton University, P.O. Box 536-20115, Egerton-Njoro, Kenya
| | - Abiy Yenesew
- Department of Chemistry, University of Nairobi, P.O. Box 30197-00100, Nairobi, Kenya
| | - Hoseah M. Akala
- United States Army Medical Research Directorate-Africa (USAMRD-A), Kenya Medical Research Institute (KEMRI)—Walter Reed Project, P.O. Box 54-40100, Kisumu, Kenya
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Wang H, Feng Y, Lu H. Low-Level Cefepime Exposure Induces High-Level Resistance in Environmental Bacteria: Molecular Mechanism and Evolutionary Dynamics. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2022; 56:15074-15083. [PMID: 35608924 DOI: 10.1021/acs.est.2c00793] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Antibiotics exert selective pressures on clinically relevant antibiotic resistance. It is critical to understand how antibiotic resistance evolves in environmental microbes exposed to subinhibitory concentrations of antibiotics and whether evolutionary dynamics and emergence of resistance are predictable. In this study, Comamonas testosteroni isolated from wastewater activated sludge were subcultured in a medium containing 10 ng/mL cefepime for 40 days (∼300 generations). Stepwise mutations were accumulated, leading to an ultimate 200-fold increase in the minimum inhibitory concentration (MIC) of cefepime. Early stage mutation in DNA polymerase-encoding gene dnaE2 played an important role in antibiotic resistance evolution. Diverse resistance mechanisms were employed and validated experimentally, including increased efflux, biofilm formation, reduced antibiotic uptake, and drug inactivation. The cefepime minimal selective concentrations (MSCs) and relative fitness of susceptible, intermediate, and resistant mutants were determined. Agent-based modeling of the modified Moran process enabled simulations of resistance evolution and predictions of the emergence time and frequency of resistant mutants. The unraveled cefepime resistance mechanisms could be employed by broader bacteria, and the newly developed model is applicable to the predictions of general resistance evolution. The improved knowledge facilitates the assessment, prediction, and mitigation of antibiotic resistance progression in antibiotic-polluted environments.
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Affiliation(s)
- Hanqing Wang
- College of Environmental and Resource Sciences, Zhejiang University, Hangzhou, Zhejiang 310058, China
| | - Youjun Feng
- Departments of Microbiology & General Intensive Care Unit of the Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310058, China
| | - Huijie Lu
- College of Environmental and Resource Sciences, Zhejiang University, Hangzhou, Zhejiang 310058, China
- Academy of Ecological Civilization, Zhejiang University, Hangzhou, Zhejiang 310058, China
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ImuA Facilitates SOS Mutagenesis by Inhibiting RecA-Mediated Activity in Myxococcus xanthus. Appl Environ Microbiol 2021; 87:e0091921. [PMID: 34190612 DOI: 10.1128/aem.00919-21] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Bacteria have two pathways to restart stalled replication forks caused by environmental stresses, error-prone translesion DNA synthesis (TLS) catalyzed by TLS polymerase and error-free template switching catalyzed by RecA, and their competition on the arrested fork affects bacterial SOS mutagenesis. DnaE2 is an error-prone TLS polymerase, and its functions require ImuA and ImuB. Here, we investigated the transcription of imuA, imuB, and dnaE2 in UV-C-irradiated Myxococcus xanthus and found that the induction of imuA occurred significantly earlier than that of the other two genes. Mutant analysis showed that unlike that of imuB or dnaE2, the deletion of imuA significantly delayed bacterial regrowth and slightly reduced the bacterial mutation frequency and UV resistance. Transcriptomic analysis revealed that the absence of ImuA released the expression of some known SOS genes, including recA1, recA2, imuB, and dnaE2. Yeast two-hybrid and pulldown analyses proved that ImuA interacts physically with RecA1 besides ImuB. Protein activity analysis indicated that ImuA had no DNA-binding activity but inhibited the DNA-binding and recombinase activity of RecA1. These findings indicate the new role of ImuA in SOS mutagenesis; that is, ImuA inhibits the recombinase activity of RecA1, thereby facilitating SOS mutagenesis in M. xanthus. IMPORTANCE DnaE2 is responsible for bacterial SOS mutagenesis in nearly one-third of sequenced bacterial strains. However, its mechanism, especially the function of one of its accessory proteins, ImuA, is still unclear. Here, we report that M. xanthus ImuA could affect SOS mutagenesis by inhibiting the recombinase activity of RecA1, which helps to explain the mechanism of DnaE2-dependent TLS and the selection of the two restart pathways to repair the stalled replication fork.
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Sekurova ON, Sun YQ, Zehl M, Rückert C, Stich A, Busche T, Kalinowski J, Zotchev SB. Coupling of the engineered DNA "mutator" to a biosensor as a new paradigm for activation of silent biosynthetic gene clusters in Streptomyces. Nucleic Acids Res 2021; 49:8396-8405. [PMID: 34197612 PMCID: PMC8373060 DOI: 10.1093/nar/gkab583] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2021] [Revised: 05/31/2021] [Accepted: 06/23/2021] [Indexed: 11/14/2022] Open
Abstract
DNA replication fidelity in Streptomyces bacteria, prolific producers of many medically important secondary metabolites, is understudied, while in Escherichia coli it is controlled by DnaQ, the ϵ subunit of DNA polymerase III (DNA PolIII). Manipulation of dnaQ paralogues in Streptomyces lividans TK24, did not lead to increased spontaneous mutagenesis in this bacterium suggesting that S. lividans DNA PolIII uses an alternative exonuclease activity for proofreading. In Mycobacterium tuberculosis, such activity is attributed to the DnaE protein representing α subunit of DNA PolIII. Eight DnaE mutants designed based on the literature data were overexpressed in S. lividans, and recombinant strains overexpressing two of these mutants displayed markedly increased frequency of spontaneous mutagenesis (up to 1000-fold higher compared to the control). One of these ‘mutators’ was combined in S. lividans with a biosensor specific for antibiotic coelimycin, which biosynthetic gene cluster is present but not expressed in this strain. Colonies giving a positive biosensor signal appeared at a frequency of ca 10–5, and all of them were found to produce coelimycin congeners. This result confirmed that our approach can be applied for chemical- and radiation-free mutagenesis in Streptomyces leading to activation of orphan biosynthetic gene clusters and discovery of novel bioactive secondary metabolites.
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Affiliation(s)
- Olga N Sekurova
- Department of Pharmaceutical Sciences, Division of Pharmacognosy, University of Vienna, Vienna, Austria
| | - Yi-Qian Sun
- Department of Biotechnology and Food Science, Norwegian University of Science and Technology (NTNU), Trondheim, Norway.,Department of Clinical and Molecular Medicine, Norwegian University of Science and Technology (NTNU), Trondheim, Norway
| | - Martin Zehl
- Department of Analytical Chemistry, Faculty of Chemistry, University of Vienna, Austria
| | - Christian Rückert
- Center for Biotechnology (CeBiTec), Universität Bielefeld, Bielefeld, Germany
| | - Anna Stich
- Department of Pharmaceutical Sciences, Division of Pharmacognosy, University of Vienna, Vienna, Austria
| | - Tobias Busche
- Center for Biotechnology (CeBiTec), Universität Bielefeld, Bielefeld, Germany
| | - Jörn Kalinowski
- Center for Biotechnology (CeBiTec), Universität Bielefeld, Bielefeld, Germany
| | - Sergey B Zotchev
- Department of Pharmaceutical Sciences, Division of Pharmacognosy, University of Vienna, Vienna, Austria
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Leal AZ, Schwebs M, Briggs E, Weisert N, Reis H, Lemgruber L, Luko K, Wilkes J, Butter F, McCulloch R, Janzen CJ. Genome maintenance functions of a putative Trypanosoma brucei translesion DNA polymerase include telomere association and a role in antigenic variation. Nucleic Acids Res 2020; 48:9660-9680. [PMID: 32890403 PMCID: PMC7515707 DOI: 10.1093/nar/gkaa686] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2019] [Revised: 08/03/2020] [Accepted: 09/03/2020] [Indexed: 12/17/2022] Open
Abstract
Maintenance of genome integrity is critical to guarantee transfer of an intact genome from parent to offspring during cell division. DNA polymerases (Pols) provide roles in both replication of the genome and the repair of a wide range of lesions. Amongst replicative DNA Pols, translesion DNA Pols play a particular role: replication to bypass DNA damage. All cells express a range of translesion Pols, but little work has examined their function in parasites, including whether the enzymes might contribute to host-parasite interactions. Here, we describe a dual function of one putative translesion Pol in African trypanosomes, which we now name TbPolIE. Previously, we demonstrated that TbPolIE is associated with telomeric sequences and here we show that RNAi-mediated depletion of TbPolIE transcripts results in slowed growth, altered DNA content, changes in cell morphology, and increased sensitivity to DNA damaging agents. We also show that TbPolIE displays pronounced localization at the nuclear periphery, and that its depletion leads to chromosome segregation defects and increased levels of endogenous DNA damage. Finally, we demonstrate that TbPolIE depletion leads to deregulation of telomeric variant surface glycoprotein genes, linking the function of this putative translesion DNA polymerase to host immune evasion by antigenic variation.
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Affiliation(s)
- Andrea Zurita Leal
- The Wellcome Centre for Integrative Parasitology, Institute of Infection, Immunity and Inflammation, University of Glasgow, Glasgow, UK
| | - Marie Schwebs
- Department of Cell & Developmental Biology, Biocenter, University of Würzburg, Würzburg, Germany
| | - Emma Briggs
- The Wellcome Centre for Integrative Parasitology, Institute of Infection, Immunity and Inflammation, University of Glasgow, Glasgow, UK
| | - Nadine Weisert
- Department of Cell & Developmental Biology, Biocenter, University of Würzburg, Würzburg, Germany
| | - Helena Reis
- Department of Cell & Developmental Biology, Biocenter, University of Würzburg, Würzburg, Germany
| | - Leandro Lemgruber
- The Wellcome Centre for Integrative Parasitology, Institute of Infection, Immunity and Inflammation, University of Glasgow, Glasgow, UK
| | - Katarina Luko
- Quantitative Proteomics, Institute of Molecular Biology (IMB), Mainz, Germany
| | - Jonathan Wilkes
- The Wellcome Centre for Integrative Parasitology, Institute of Infection, Immunity and Inflammation, University of Glasgow, Glasgow, UK
| | - Falk Butter
- Quantitative Proteomics, Institute of Molecular Biology (IMB), Mainz, Germany
| | - Richard McCulloch
- The Wellcome Centre for Integrative Parasitology, Institute of Infection, Immunity and Inflammation, University of Glasgow, Glasgow, UK
| | - Christian J Janzen
- Department of Cell & Developmental Biology, Biocenter, University of Würzburg, Würzburg, Germany
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Luján AM, Moyano AJ, Martino RA, Feliziani S, Urretavizcaya M, Smania AM. ImuB and ImuC contribute to UV-induced mutagenesis as part of the SOS regulon in Pseudomonas aeruginosa. ENVIRONMENTAL AND MOLECULAR MUTAGENESIS 2019; 60:594-601. [PMID: 30921487 DOI: 10.1002/em.22290] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/04/2018] [Revised: 03/22/2019] [Accepted: 03/25/2019] [Indexed: 06/09/2023]
Abstract
DNA damage-induced mutagenesis is a process governed by the SOS system that requires the activity of specialized DNA polymerases. These polymerases, which are devoid of proof-reading activity, serve to increase the probability of survival under stressful conditions in exchange for an error-prone DNA synthesis. As an opportunistic pathogen of humans, Pseudomonas aeruginosa employs adaptive responses that originally evolved for survival in many diverse and often stressful environmental conditions, where the action of error-prone DNA polymerases may be crucial. In this study, we have investigated the role of the polymerases ImuB and ImuC in P. aeruginosa DNA-damage induced mutagenesis. UV irradiation of imuB- and imuC-deletion mutants showed that both genes contribute to UV-induced mutagenesis in this bacterium. Furthermore, we confirmed that UV treatment significantly increase the expression levels of the imuB and imuC genes and that they are co-transcribed as a single transcriptional unit under the control of LexA as part of the SOS regulon in P. aeruginosa. Environ. Mol. Mutagen. 2019. © 2019 Wiley Periodicals, Inc.
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Affiliation(s)
- Adela M Luján
- Universidad Nacional de Córdoba, Facultad de Ciencias Químicas, Departamento de Química Biológica Ranwel Caputto, Córdoba, Argentina
- CONICET, Universidad Nacional de Córdoba, Centro de Investigaciones en Química Biológica de Córdoba (CIQUIBIC), Córdoba, Argentina
| | - Alejandro J Moyano
- Universidad Nacional de Córdoba, Facultad de Ciencias Químicas, Departamento de Química Biológica Ranwel Caputto, Córdoba, Argentina
- CONICET, Universidad Nacional de Córdoba, Centro de Investigaciones en Química Biológica de Córdoba (CIQUIBIC), Córdoba, Argentina
| | - Román A Martino
- Universidad Nacional de Córdoba, Facultad de Ciencias Químicas, Departamento de Química Biológica Ranwel Caputto, Córdoba, Argentina
- CONICET, Universidad Nacional de Córdoba, Centro de Investigaciones en Química Biológica de Córdoba (CIQUIBIC), Córdoba, Argentina
| | - Sofía Feliziani
- Universidad Nacional de Córdoba, Facultad de Ciencias Químicas, Departamento de Química Biológica Ranwel Caputto, Córdoba, Argentina
- CONICET, Universidad Nacional de Córdoba, Centro de Investigaciones en Química Biológica de Córdoba (CIQUIBIC), Córdoba, Argentina
| | - Mariana Urretavizcaya
- Universidad Nacional de Córdoba, Facultad de Ciencias Químicas, Departamento de Química Biológica Ranwel Caputto, Córdoba, Argentina
- CONICET, Universidad Nacional de Córdoba, Centro de Investigaciones en Química Biológica de Córdoba (CIQUIBIC), Córdoba, Argentina
| | - Andrea M Smania
- Universidad Nacional de Córdoba, Facultad de Ciencias Químicas, Departamento de Química Biológica Ranwel Caputto, Córdoba, Argentina
- CONICET, Universidad Nacional de Córdoba, Centro de Investigaciones en Química Biológica de Córdoba (CIQUIBIC), Córdoba, Argentina
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Timinskas K, Venclovas Č. New insights into the structures and interactions of bacterial Y-family DNA polymerases. Nucleic Acids Res 2019; 47:4393-4405. [PMID: 30916324 PMCID: PMC6511836 DOI: 10.1093/nar/gkz198] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2018] [Revised: 03/09/2019] [Accepted: 03/19/2019] [Indexed: 11/15/2022] Open
Abstract
Bacterial Y-family DNA polymerases are usually classified into DinB (Pol IV), UmuC (the catalytic subunit of Pol V) and ImuB, a catalytically dead essential component of the ImuA-ImuB-DnaE2 mutasome. However, the true diversity of Y-family polymerases is unknown. Furthermore, for most of them the structures are unavailable and interactions are poorly characterized. To gain a better understanding of bacterial Y-family DNA polymerases, we performed a detailed computational study. It revealed substantial diversity, far exceeding traditional classification. We found that a large number of subfamilies feature a C-terminal extension next to the common Y-family region. Unexpectedly, in most C-terminal extensions we identified a region homologous to the N-terminal oligomerization motif of RecA. This finding implies a universal mode of interaction between Y-family members and RecA (or ImuA), in the case of Pol V strongly supported by experimental data. In gram-positive bacteria, we identified a putative Pol V counterpart composed of a Y-family polymerase, a YolD homolog and RecA. We also found ImuA-ImuB-DnaE2 variants lacking ImuA, but retaining active or inactive Y-family polymerase, a standalone ImuB C-terminal domain and/or DnaE2. In summary, our analyses revealed that, despite considerable diversity, bacterial Y-family polymerases share previously unanticipated similarities in their structural domains/motifs and interactions.
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Affiliation(s)
- Kęstutis Timinskas
- Institute of Biotechnology, Life Sciences Center, Vilnius University, Saulėtekio 7, Vilnius LT-10257, Lithuania
| | - Česlovas Venclovas
- Institute of Biotechnology, Life Sciences Center, Vilnius University, Saulėtekio 7, Vilnius LT-10257, Lithuania
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Moldovan MA. Prokaryotic and Mitochondrial Linear Genomes: Their Genesis, Evolutionary Significance, and the Problem of Replicating Chromosome Ends. Mol Biol 2019. [DOI: 10.1134/s0026893319020122] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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9
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Yang CC, Tseng SM, Pan HY, Huang CH, Chen CW. Telomere associated primase Tap repairs truncated telomeres of Streptomyces. Nucleic Acids Res 2017; 45:5838-5849. [PMID: 28369604 PMCID: PMC5449611 DOI: 10.1093/nar/gkx189] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2017] [Accepted: 03/11/2017] [Indexed: 01/01/2023] Open
Abstract
Replication of the linear chromosomes of soil bacteria Streptomyces proceeds from an internal origin towards the telomeres, followed by patching of the resulting terminal single-strand overhangs by DNA synthesis using terminal proteins as the primer, which remains covalently bound to the 5΄ ends of the DNA. In most Streptomyces chromosomes, the end patching requires the single-strand overhangs, terminal protein Tpg, and terminal associated protein Tap. The telomere overhangs contain several palindromic sequences capable of forming stable hairpins. Previous in vitro deoxynucleotidylation studies indicated that Tap adds the Palindrome I sequence to Tpg, which is extended by a polymerase to fill the gap. In this study, the stringency of Palindrome I sequence was examined by an in vitro deoxynucleotidylation system and in vivo replication. Several nt in Palindrome I were identified to be critical for priming. While the first 3 G on the template were required for deoxynucleotidylation in vitro, deletions of them could be suppressed by the presence of dGTP. In vivo, deletions of these G were also tolerated, and the telomere sequence was restored in the linear plasmid DNA. Our results indicated that the truncated telomeres were repaired by extension synthesis by Tap on the foldback Palindrome I sequence.
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Affiliation(s)
- Chien-Chin Yang
- Department of Chemistry, Chung-Yuan Christian University, Chung-li, Taiwan
- To whom correspondence should be addressed. Tel: +886 3 2653303; Fax: +886 3 2653399;
| | - Shu-Min Tseng
- Department of Chemistry, Chung-Yuan Christian University, Chung-li, Taiwan
| | - Hung-Yin Pan
- Institute of Biochemical and Biomedical Engineering, National Taipei University of Technology, Taipei, Taiwan
| | - Chih-Hung Huang
- Institute of Biochemical and Biomedical Engineering, National Taipei University of Technology, Taipei, Taiwan
| | - Carton W. Chen
- Department of Life Sciences and Institute of Genome Sciences, National Yang-Ming University, Taipei, Taiwan
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Contesini FJ, Liberato MV, Rubio MV, Calzado F, Zubieta MP, Riaño-Pachón DM, Squina FM, Bracht F, Skaf MS, Damasio AR. Structural and functional characterization of a highly secreted α-l-arabinofuranosidase (GH62) from Aspergillus nidulans grown on sugarcane bagasse. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2017; 1865:1758-1769. [PMID: 28890404 DOI: 10.1016/j.bbapap.2017.09.001] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/15/2017] [Revised: 08/31/2017] [Accepted: 09/04/2017] [Indexed: 12/30/2022]
Abstract
Carbohydrate-Active Enzymes are key enzymes for biomass-to-bioproducts conversion. α-l-Arabinofuranosidases that belong to the Glycoside Hydrolase family 62 (GH62) have important applications in biofuel production from plant biomass by hydrolyzing arabinoxylans, found in both the primary and secondary cell walls of plants. In this work, we identified a GH62 α-l-arabinofuranosidase (AnAbf62Awt) that was highly secreted when Aspergillus nidulans was cultivated on sugarcane bagasse. The gene AN7908 was cloned and transformed in A. nidulans for homologous production of AnAbf62Awt, and we confirmed that the enzyme is N-glycosylated at asparagine 83 by mass spectrometry analysis. The enzyme was also expressed in Escherichia coli and the studies of circular dichroism showed that the melting temperature and structural profile of AnAbf62Awt and the non-glycosylated enzyme from E. coli (AnAbf62Adeglyc) were highly similar. In addition, the designed glycomutant AnAbf62AN83Q presented similar patterns of secretion and activity to the AnAbf62Awt, indicating that the N-glycan does not influence the properties of this enzyme. The crystallographic structure of AnAbf62Adeglyc was obtained and the 1.7Å resolution model showed a five-bladed β-propeller fold, which is conserved in family GH62. Mutants AnAbf62AY312F and AnAbf62AY312S showed that Y312 was an important substrate-binding residue. Molecular dynamics simulations indicated that the loop containing Y312 could access different conformations separated by moderately low energy barriers. One of these conformations, comprising a local minimum, is responsible for placing Y312 in the vicinity of the arabinose glycosidic bond, and thus, may be important for catalytic efficiency.
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Affiliation(s)
- Fabiano Jares Contesini
- Institute of Biology, University of Campinas - UNICAMP, Campinas, SP CEP 13083-862, Brazil; Laboratório Nacional de Ciência e Tecnologia do Bioetanol (CTBE), Centro Nacional de Pesquisa em Energia e Materiais (CNPEM), Campinas, SP, Caixa Postal 6192, 13083-970, Brazil
| | - Marcelo Vizoná Liberato
- Laboratório Nacional de Ciência e Tecnologia do Bioetanol (CTBE), Centro Nacional de Pesquisa em Energia e Materiais (CNPEM), Campinas, SP, Caixa Postal 6192, 13083-970, Brazil
| | - Marcelo Ventura Rubio
- Institute of Biology, University of Campinas - UNICAMP, Campinas, SP CEP 13083-862, Brazil
| | - Felipe Calzado
- Institute of Biology, University of Campinas - UNICAMP, Campinas, SP CEP 13083-862, Brazil
| | | | - Diego Mauricio Riaño-Pachón
- Laboratório Nacional de Ciência e Tecnologia do Bioetanol (CTBE), Centro Nacional de Pesquisa em Energia e Materiais (CNPEM), Campinas, SP, Caixa Postal 6192, 13083-970, Brazil; Laboratory of Regulatory Systems Biology, Department of Biochemistry, Institute of Chemistry, University of São Paulo, São Paulo, SP, CEP: 05508-000, Brazil
| | - Fabio Marcio Squina
- Programa de Processos Tecnológicos e Ambientais, Universidade de Sorocaba, (UNISO), Sorocaba, SP, CEP 18023-000, Brazil
| | - Fabricio Bracht
- Institute of Chemistry, University of Campinas - UNICAMP, Campinas, SP CEP: 13084-862, Brazil
| | - Munir S Skaf
- Institute of Chemistry, University of Campinas - UNICAMP, Campinas, SP CEP: 13084-862, Brazil
| | - André Ricardo Damasio
- Institute of Biology, University of Campinas - UNICAMP, Campinas, SP CEP 13083-862, Brazil.
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11
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Ilmjärv T, Naanuri E, Kivisaar M. Contribution of increased mutagenesis to the evolution of pollutants-degrading indigenous bacteria. PLoS One 2017; 12:e0182484. [PMID: 28777807 PMCID: PMC5544203 DOI: 10.1371/journal.pone.0182484] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2016] [Accepted: 07/19/2017] [Indexed: 12/20/2022] Open
Abstract
Bacteria can rapidly evolve mechanisms allowing them to use toxic environmental pollutants as a carbon source. In the current study we examined whether the survival and evolution of indigenous bacteria with the capacity to degrade organic pollutants could be connected with increased mutation frequency. The presence of constitutive and transient mutators was monitored among 53 pollutants-degrading indigenous bacterial strains. Only two strains expressed a moderate mutator phenotype and six were hypomutators, which implies that constitutively increased mutability has not been prevalent in the evolution of pollutants degrading bacteria. At the same time, a large proportion of the studied indigenous strains exhibited UV-irradiation-induced mutagenesis, indicating that these strains possess error-prone DNA polymerases which could elevate mutation frequency transiently under the conditions of DNA damage. A closer inspection of two Pseudomonas fluorescens strains PC20 and PC24 revealed that they harbour genes for ImuC (DnaE2) and more than one copy of genes for Pol V. Our results also revealed that availability of other nutrients in addition to aromatic pollutants in the growth environment of bacteria affects mutagenic effects of aromatic compounds. These results also implied that mutagenicity might be affected by a factor of how long bacteria have evolved to use a particular pollutant as a carbon source.
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Affiliation(s)
- Tanel Ilmjärv
- Department of Genetics, Institute of Molecular and Cell Biology, University of Tartu, Tartu, Estonia
| | - Eve Naanuri
- Department of Genetics, Institute of Molecular and Cell Biology, University of Tartu, Tartu, Estonia
| | - Maia Kivisaar
- Department of Genetics, Institute of Molecular and Cell Biology, University of Tartu, Tartu, Estonia
- * E-mail:
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12
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Abstract
Faithful replication and maintenance of the genome are essential to the ability of any organism to survive and propagate. For an obligate pathogen such as Mycobacterium tuberculosis that has to complete successive cycles of transmission, infection, and disease in order to retain a foothold in the human population, this requires that genome replication and maintenance must be accomplished under the metabolic, immune, and antibiotic stresses encountered during passage through variable host environments. Comparative genomic analyses have established that chromosomal mutations enable M. tuberculosis to adapt to these stresses: the emergence of drug-resistant isolates provides direct evidence of this capacity, so too the well-documented genetic diversity among M. tuberculosis lineages across geographic loci, as well as the microvariation within individual patients that is increasingly observed as whole-genome sequencing methodologies are applied to clinical samples and tuberculosis (TB) disease models. However, the precise mutagenic mechanisms responsible for M. tuberculosis evolution and adaptation are poorly understood. Here, we summarize current knowledge of the machinery responsible for DNA replication in M. tuberculosis, and discuss the potential contribution of the expanded complement of mycobacterial DNA polymerases to mutagenesis. We also consider briefly the possible role of DNA replication-in particular, its regulation and coordination with cell division-in the ability of M. tuberculosis to withstand antibacterial stresses, including host immune effectors and antibiotics, through the generation at the population level of a tolerant state, or through the formation of a subpopulation of persister bacilli-both of which might be relevant to the emergence and fixation of genetic drug resistance.
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13
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Peng R, Chen JH, Feng WW, Zhang Z, Yin J, Li ZS, Li YZ. Error-prone DnaE2 Balances the Genome Mutation Rates in Myxococcus xanthus DK1622. Front Microbiol 2017; 8:122. [PMID: 28203231 PMCID: PMC5285347 DOI: 10.3389/fmicb.2017.00122] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2016] [Accepted: 01/17/2017] [Indexed: 11/24/2022] Open
Abstract
dnaE is an alpha subunit of the tripartite protein complex of DNA polymerase III that is responsible for the replication of bacterial genome. The dnaE gene is often duplicated in many bacteria, and the duplicated dnaE gene was reported dispensable for cell survivals and error-prone in DNA replication in a mystery. In this study, we found that all sequenced myxobacterial genomes possessed two dnaE genes. The duplicate dnaE genes were both highly conserved but evolved divergently, suggesting their importance in myxobacteria. Using Myxococcus xanthus DK1622 as a model, we confirmed that dnaE1 (MXAN_5844) was essential for cell survival, while dnaE2 (MXAN_3982) was dispensable and encoded an error-prone enzyme for replication. The deletion of dnaE2 had small effects on cellular growth and social motility, but significantly decreased the development and sporulation abilities, which could be recovered by the complementation of dnaE2. The expression of dnaE1 was always greatly higher than that of dnaE2 in either the growth or developmental stage. However, overexpression of dnaE2 could not make dnaE1 deletable, probably due to their protein structural and functional divergences. The dnaE2 overexpression not only improved the growth, development and sporulation abilities, but also raised the genome mutation rate of M. xanthus. We argued that the low-expressed error-prone DnaE2 played as a balancer for the genome mutation rates, ensuring low mutation rates for cell adaptation in new environments but avoiding damages from high mutation rates to cells.
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Affiliation(s)
- Ran Peng
- State Key Laboratory of Microbial Technology, School of Life Science, Shandong University Jinan, China
| | - Jiang-He Chen
- State Key Laboratory of Microbial Technology, School of Life Science, Shandong University Jinan, China
| | - Wan-Wan Feng
- State Key Laboratory of Microbial Technology, School of Life Science, Shandong University Jinan, China
| | - Zheng Zhang
- State Key Laboratory of Microbial Technology, School of Life Science, Shandong University Jinan, China
| | - Jun Yin
- State Key Laboratory of Microbial Technology, School of Life Science, Shandong University Jinan, China
| | - Ze-Shuo Li
- State Key Laboratory of Microbial Technology, School of Life Science, Shandong University Jinan, China
| | - Yue-Zhong Li
- State Key Laboratory of Microbial Technology, School of Life Science, Shandong University Jinan, China
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Jatsenko T, Sidorenko J, Saumaa S, Kivisaar M. DNA Polymerases ImuC and DinB Are Involved in DNA Alkylation Damage Tolerance in Pseudomonas aeruginosa and Pseudomonas putida. PLoS One 2017; 12:e0170719. [PMID: 28118378 PMCID: PMC5261740 DOI: 10.1371/journal.pone.0170719] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2016] [Accepted: 01/09/2017] [Indexed: 12/12/2022] Open
Abstract
Translesion DNA synthesis (TLS), facilitated by low-fidelity polymerases, is an important DNA damage tolerance mechanism. Here, we investigated the role and biological function of TLS polymerase ImuC (former DnaE2), generally present in bacteria lacking DNA polymerase V, and TLS polymerase DinB in response to DNA alkylation damage in Pseudomonas aeruginosa and P. putida. We found that TLS DNA polymerases ImuC and DinB ensured a protective role against N- and O-methylation induced by N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) in both P. aeruginosa and P. putida. DinB also appeared to be important for the survival of P. aeruginosa and rapidly growing P. putida cells in the presence of methyl methanesulfonate (MMS). The role of ImuC in protection against MMS-induced damage was uncovered under DinB-deficient conditions. Apart from this, both ImuC and DinB were critical for the survival of bacteria with impaired base excision repair (BER) functions upon alkylation damage, lacking DNA glycosylases AlkA and/or Tag. Here, the increased sensitivity of imuCdinB double deficient strains in comparison to single mutants suggested that the specificity of alkylated DNA lesion bypass of DinB and ImuC might also be different. Moreover, our results demonstrated that mutagenesis induced by MMS in pseudomonads was largely ImuC-dependent. Unexpectedly, we discovered that the growth temperature of bacteria affected the efficiency of DinB and ImuC in ensuring cell survival upon alkylation damage. Taken together, the results of our study disclosed the involvement of ImuC in DNA alkylation damage tolerance, especially at low temperatures, and its possible contribution to the adaptation of pseudomonads upon DNA alkylation damage via increased mutagenesis.
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Affiliation(s)
- Tatjana Jatsenko
- Department of Genetics, Institute of Molecular and Cell Biology, University of Tartu, Tartu, Estonia
- * E-mail: (MK); (TJ)
| | - Julia Sidorenko
- Department of Genetics, Institute of Molecular and Cell Biology, University of Tartu, Tartu, Estonia
| | - Signe Saumaa
- Department of Genetics, Institute of Molecular and Cell Biology, University of Tartu, Tartu, Estonia
| | - Maia Kivisaar
- Department of Genetics, Institute of Molecular and Cell Biology, University of Tartu, Tartu, Estonia
- * E-mail: (MK); (TJ)
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15
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Yang CC, Tseng SM, Chen CW. Telomere-associated proteins add deoxynucleotides to terminal proteins during replication of the telomeres of linear chromosomes and plasmids in Streptomyces. Nucleic Acids Res 2015; 43:6373-83. [PMID: 25883134 PMCID: PMC4513846 DOI: 10.1093/nar/gkv302] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2015] [Revised: 03/17/2015] [Accepted: 03/25/2015] [Indexed: 12/15/2022] Open
Abstract
Typical telomeres of linear chromosomes and plasmids of soil bacteria Streptomyces consist of tightly packed palindromic sequences with a terminal protein ('TP') covalently attached to the 5' end of the DNA. Replication of these linear replicons is initiated internally and proceeds bidirectionally toward the telomeres, which leaves single-strand overhangs at the 3' ends. These overhangs are filled by DNA synthesis using the TPs as the primers ('end patching'). The gene encoding for typical TP, tpg, forms an operon with tap, encoding an essential telomere-associated protein, which binds TP and the secondary structures formed by the 3' overhangs. Previously one of the two translesion synthesis DNA polymerases, DinB1 or DinB2, was proposed to catalyze the protein-primed synthesis. However, using an in vitro end-patching system, we discovered that Tpg and Tap alone could carry out the protein-primed synthesis to a length of 13 nt. Similarly, an 'atypical' terminal protein, Tpc, and its cognate telomere-associated protein, Tac, of SCP1 plasmid, were sufficient to achieve protein-primed synthesis in the absence of additional polymerase. These results indicate that these two telomere-associated proteins possess polymerase activities alone or in complex with the cognate TPs.
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Affiliation(s)
- Chien-Chin Yang
- Department of Chemistry, Chung-Yuan Christian University, Chung-li 32023, Taiwan
| | - Shu-Min Tseng
- Department of Chemistry, Chung-Yuan Christian University, Chung-li 32023, Taiwan
| | - Carton W Chen
- Department of Life Sciences and Institute of Genome Sciences, National Yang-Ming University, Shih-Pai, Taipei 11221, Taiwan
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Timinskas K, Balvočiūtė M, Timinskas A, Venclovas Č. Comprehensive analysis of DNA polymerase III α subunits and their homologs in bacterial genomes. Nucleic Acids Res 2013; 42:1393-413. [PMID: 24106089 PMCID: PMC3919608 DOI: 10.1093/nar/gkt900] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
The analysis of ∼2000 bacterial genomes revealed that they all, without a single exception, encode one or more DNA polymerase III α-subunit (PolIIIα) homologs. Classified into C-family of DNA polymerases they come in two major forms, PolC and DnaE, related by ancient duplication. While PolC represents an evolutionary compact group, DnaE can be further subdivided into at least three groups (DnaE1-3). We performed an extensive analysis of various sequence, structure and surface properties of all four polymerase groups. Our analysis suggests a specific evolutionary pathway leading to PolC and DnaE from the last common ancestor and reveals important differences between extant polymerase groups. Among them, DnaE1 and PolC show the highest conservation of the analyzed properties. DnaE3 polymerases apparently represent an ‘impaired’ version of DnaE1. Nonessential DnaE2 polymerases, typical for oxygen-using bacteria with large GC-rich genomes, have a number of features in common with DnaE3 polymerases. The analysis of polymerase distribution in genomes revealed three major combinations: DnaE1 either alone or accompanied by one or more DnaE2s, PolC + DnaE3 and PolC + DnaE1. The first two combinations are present in Escherichia coli and Bacillus subtilis, respectively. The third one (PolC + DnaE1), found in Clostridia, represents a novel, so far experimentally uncharacterized, set.
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Affiliation(s)
- Kestutis Timinskas
- Institute of Biotechnology, Vilnius University, Graičiūno 8, Vilnius LT-02241, Lithuania
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17
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Yang CC, Sun WC, Wang WY, Huang CH, Lu FS, Tseng SM, Chen CW. Mutational analysis of the terminal protein Tpg of Streptomyces chromosomes: identification of the deoxynucleotidylation site. PLoS One 2013; 8:e56322. [PMID: 23457549 PMCID: PMC3572947 DOI: 10.1371/journal.pone.0056322] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2012] [Accepted: 01/08/2013] [Indexed: 11/23/2022] Open
Abstract
The linear chromosomes and linear plasmids of Streptomyces are capped by terminal proteins (TPs) covalently bound to the 5' ends of the DNA. The TPs serve as primers for DNA synthesis that patches in the single-stranded gaps at the telomeres resulting from the bi-directional replication ('end patching'). Typical Streptomyces TPs, designated Tpgs, are conserved in sequence and size (about 185 amino acids), and contain a predicted helix-turn-helix domain and a functional nuclear localization signal. The Tpg-encoding gene (tpg) is often accompanied by an upstream gene tap that encodes an essential telomere-associating protein. Five lone tpg variants (not accompanied by tap) from various Streptomyces species were tested, and three were found to be pseudogenes. The lone tpg variant on the SLP2 plasmid, although functional, still requires the presence of tap on the chromosome for end patching. Using a combination of in vitro deoxynucleotidylation, physical localization, and genetic analysis, we identified the threonine at position 114 (T114) in Tpg of Streptomyces lividans chromosome as the deoxynucleotidylated site. Interestingly, T114 could be substituted by a serine without destroying the priming activity of Tpg in vitro and in vivo. Such T114S substitution is seen in and a number of pseudogenes as well as functional Tpgs. T114 lies in a predicted coil flanked by two short helixes in a highly hydrophilic region. The location and structural arrangement of the deoxynucleotidylated site in Tpg is similar to those in the TPs of phage ø 29 and adenoviruses. However, these TPs are distinct in their sequences and sizes, indicating that they have evolved independently during evolution. Using naturally occurring and artificially created tpg variants, we further identified several amino acid residues in the N-terminus and the helix-turn-helix domain that were important for functionality.
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Affiliation(s)
- Chien-Chin Yang
- Department of Chemistry, Chung-Yuan Christian University, Chung-li, Taiwan
| | - We-Chi Sun
- Department of Chemistry, Chung-Yuan Christian University, Chung-li, Taiwan
| | - Wan-Yu Wang
- Department of Chemistry, Chung-Yuan Christian University, Chung-li, Taiwan
| | - Chi-Hung Huang
- Institute of Biotechnology, National Taipei University of Technology, Taipei, Taiwan
| | - Fang-Shy Lu
- Department of Chemistry, Chung-Yuan Christian University, Chung-li, Taiwan
| | - Shu-Min Tseng
- Department of Chemistry, Chung-Yuan Christian University, Chung-li, Taiwan
| | - Carton W. Chen
- Department of Life Sciences, Institute of Genome Sciences, National Yang-Ming University, Shih-Pai, Taipei, Taiwan
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Dib JR, Liebl W, Wagenknecht M, Farías ME, Meinhardt F. Extrachromosomal genetic elements in Micrococcus. Appl Microbiol Biotechnol 2012; 97:63-75. [PMID: 23138713 DOI: 10.1007/s00253-012-4539-5] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2012] [Revised: 10/22/2012] [Accepted: 10/22/2012] [Indexed: 10/27/2022]
Abstract
Micrococci are Gram-positive G + C-rich, nonmotile, nonspore-forming actinomycetous bacteria. Micrococcus comprises ten members, with Micrococcus luteus being the type species. Representatives of the genus play important roles in the biodegradation of xenobiotics, bioremediation processes, production of biotechnologically important enzymes or bioactive compounds, as test strains in biological assays for lysozyme and antibiotics, and as infective agents in immunocompromised humans. The first description of plasmids dates back approximately 28 years, when several extrachromosomal elements ranging in size from 1.5 to 30.2 kb were found in Micrococcus luteus. Up to the present, a number of circular plasmids conferring antibiotic resistance, the ability to degrade aromatic compounds, and osmotolerance are known, as well as cryptic elements with unidentified functions. Here, we review the Micrococcus extrachromosomal traits reported thus far including phages and the only quite recently described large linear extrachromosomal genetic elements, termed linear plasmids, which range in size from 75 kb (pJD12) to 110 kb (pLMA1) and which confer putative advantageous capabilities, such as antibiotic or heavy metal resistances (inferred from sequence analyses and curing experiments). The role of the extrachromosomal elements for the frequently proven ecological and biotechnological versatility of the genus will be addressed as well as their potential for the development and use as genetic tools.
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Affiliation(s)
- Julián Rafael Dib
- Laboratorio de Investigaciones Microbiológicas de Lagunas Andinas (LIMLA), Planta Piloto de Procesos Industriales Microbiológicos (PROIMI)-CONICET, Av. Belgrano y Pje. Caseros, 4000, Tucumán, Argentina
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19
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Multiple strategies for translesion synthesis in bacteria. Cells 2012; 1:799-831. [PMID: 24710531 PMCID: PMC3901139 DOI: 10.3390/cells1040799] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2012] [Revised: 09/29/2012] [Accepted: 09/30/2012] [Indexed: 12/16/2022] Open
Abstract
Damage to DNA is common and can arise from numerous environmental and endogenous sources. In response to ubiquitous DNA damage, Y-family DNA polymerases are induced by the SOS response and are capable of bypassing DNA lesions. In Escherichia coli, these Y-family polymerases are DinB and UmuC, whose activities are modulated by their interaction with the polymerase manager protein UmuD. Many, but not all, bacteria utilize DinB and UmuC homologs. Recently, a C-family polymerase named ImuC, which is similar in primary structure to the replicative DNA polymerase DnaE, was found to be able to copy damaged DNA and either carry out or suppress mutagenesis. ImuC is often found with proteins ImuA and ImuB, the latter of which is similar to Y‑family polymerases, but seems to lack the catalytic residues necessary for polymerase activity. This imuAimuBimuC mutagenesis cassette represents a widespread alternative strategy for translesion synthesis and mutagenesis in bacteria. Bacterial Y‑family and ImuC DNA polymerases contribute to replication past DNA damage and the acquisition of antibiotic resistance.
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