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Cd-induced cytosolic proteome changes in the cyanobacterium Anabaena sp. PCC7120 are mediated by LexA as one of the regulatory proteins. BIOCHIMICA ET BIOPHYSICA ACTA. PROTEINS AND PROTEOMICS 2023; 1871:140902. [PMID: 36716944 DOI: 10.1016/j.bbapap.2023.140902] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/29/2022] [Revised: 01/10/2023] [Accepted: 01/23/2023] [Indexed: 01/28/2023]
Abstract
LexA, a well-characterized transcriptional repressor of SOS genes in heterotrophic bacteria, has been shown to regulate diverse genes in cyanobacteria. An earlier study showed that LexA overexpression in a cyanobacterium, Anabaena sp. PCC7120 reduces its tolerance to Cd stress. This was later shown to be due to modulation of photosynthetic redox poising by LexA under Cd stress. However, due to the global regulatory nature of LexA and the prior prediction of AnLexA-box in a few heavy metal-responsive genes, we speculated that LexA has a broad role in Cd tolerance, with regulation over a variety of Cd stress-responsive genes in addition to photosynthetic genes. Thus, to further expand the knowledge on the regulatory role of LexA in Cd stress tolerance, a cytosolic proteome profiling of Anabaena constitutively overexpressing LexA upon Cd stress was performed. The proteomic study revealed 25 differentially accumulated proteins (DAPs) in response to the combined effect of LexA overexpression and Cd stress, and the other 11 DAPs exclusively in response to either LexA overexpression or Cd stress. The 36 identified proteins were related with a variety of functions, including photosynthesis, C-metabolism, antioxidants, protein turnover, post-transcriptional modifications, and a few unknown and hypothetical proteins. The regulation of LexA on corresponding genes, and six previously reported Cd efflux transporters, was further validated by the presence of AnLexA-boxes, transcript, and/or promoter analyses. In a nutshell, this study identifies the regulation of Anabaena LexA on several Cd stress-responsive genes of various functions, hence expanding the regulatory role of LexA under Cd stress.
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Pradhan M, Kumar A, Kirti A, Pandey S, Rajaram H. NtcA, LexA and heptamer repeats involved in the multifaceted regulation of DNA repair genes recF, recO and recR in the cyanobacterium Nostoc PCC7120. BIOCHIMICA ET BIOPHYSICA ACTA. GENE REGULATORY MECHANISMS 2023; 1866:194907. [PMID: 36638863 DOI: 10.1016/j.bbagrm.2023.194907] [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: 11/07/2022] [Revised: 01/01/2023] [Accepted: 01/02/2023] [Indexed: 01/11/2023]
Abstract
Regulation of DNA repair genes in cyanobacteria is an unexplored field despite some of them exhibiting high radio-resistance. With RecF pathway speculated to be the major double strand break repair pathway in Nostoc sp. strain PCC7120, regulation of recF, recO and recR genes was investigated. Bioinformatic approach-based identification of promoter and regulatory elements was validated using qRT-PCR analysis, reporter gene and DNA binding assays. Different deletion constructs of the upstream regulatory regions of these genes were analysed in host Nostoc as well as heterologous system Escherichia coli. Studies revealed: (1) Positive regulation of all three genes by NtcA, (2) Negative regulation by LexA, (3) Involvement of contiguous heptamer repeats with/without its yet to be identified interacting partner in regulating (i) binding of NtcA and LexA to recO promoter and its translation, (ii) transcription or translation of recF, (4) Translational regulation of recF and recO through non-canonical and distant S.D. sequence and of recR through a rare initiation codon. Presence of NtcA either precludes binding of LexA to AnLexA-Box or negates its repressive action resulting in higher expression of these genes under nitrogen-fixing conditions in Nostoc. Thus, in Nostoc, expression of recF, recO and recR genes is intricately regulated through multiple regulatory elements/proteins. Contiguous heptamer repeats present across the Nostoc genome in the vicinity of start codon or promoter is likely to have a global regulatory role. This is the first report detailing regulation of DSB repair genes in any algae.
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Affiliation(s)
- Mitali Pradhan
- Cyanobacterial Stress Biology and Biotechnology Section, Molecular Biology Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085, India; Homi Bhabha National Institute, Training School Complex, Anushakti Nagar, Mumbai 400094, India
| | - Arvind Kumar
- Cyanobacterial Stress Biology and Biotechnology Section, Molecular Biology Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085, India
| | - Anurag Kirti
- Cyanobacterial Stress Biology and Biotechnology Section, Molecular Biology Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085, India
| | - Sarita Pandey
- Cyanobacterial Stress Biology and Biotechnology Section, Molecular Biology Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085, India
| | - Hema Rajaram
- Cyanobacterial Stress Biology and Biotechnology Section, Molecular Biology Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085, India; Homi Bhabha National Institute, Training School Complex, Anushakti Nagar, Mumbai 400094, India.
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Srivastava A, Kumar A, Biswas S, Kumar R, Srivastava V, Rajaram H, Mishra Y. Gamma (γ)-radiation stress response of the cyanobacterium Anabaena sp. PCC7120: Regulatory role of LexA and photophysiological changes. PLANT SCIENCE : AN INTERNATIONAL JOURNAL OF EXPERIMENTAL PLANT BIOLOGY 2023; 326:111529. [PMID: 36332765 DOI: 10.1016/j.plantsci.2022.111529] [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: 07/05/2022] [Revised: 10/28/2022] [Accepted: 10/30/2022] [Indexed: 06/16/2023]
Abstract
High radioresistance of the cyanobacterium, Anabaena sp. PCC7120 has been attributed to efficient DNA repair, protein recycling, and oxidative stress management. However, the regulatory network involved in these batteries of responses remains unexplored. In the present study, the role of a global regulator, LexA in modulating gamma (γ)-radiation stress response of Anabaena was investigated. Comparison of the cytosolic proteome profiles upon γ-radiation in recombinant Anabaena strains, AnpAM (vector-control) and AnlexA+ (LexA-overexpressing), revealed 41 differentially accumulated proteins, corresponding to 29 distinct proteins. LexA was found to be involved in the regulation of 27 of the corresponding genes based on the presence of AnLexA-Box, EMSA, and/or qRT-PCR studies. The majority of the regulated genes were found to be involved in C-assimilation either through photosynthesis or C-catabolism and oxidative stress alleviation. Photosynthesis, measured in terms of PSII photophysiological parameters and thylakoid membrane proteome was found to be affected by γ-radiation in both AnpAM and AnlexA+ cells, with LexA affecting them even under control growth conditions. Thus, LexA functioned as one of the transcriptional regulators involved in modulating γ-radiation stress response in Anabaena. This study could pave the way for a deeper understanding of the regulation of γ-radiation-responsive genes in cyanobacteria at large.
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Affiliation(s)
- Akanksha Srivastava
- Department of Botany, Centre of Advanced Study in Botany, Institute of Science, Banaras Hindu University, Varanasi 221005, India
| | - Arvind Kumar
- Molecular Biology Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085, India
| | - Subhankar Biswas
- Department of Botany, Centre of Advanced Study in Botany, Institute of Science, Banaras Hindu University, Varanasi 221005, India
| | - Rajender Kumar
- Division of Glycoscience, Department of Chemistry, School of Engineering Sciences in Chemistry, Biotechnology and Health, Royal Institute of Technology (KTH), AlbaNova University Centre, Stockholm 10691, Sweden
| | - Vaibhav Srivastava
- Division of Glycoscience, Department of Chemistry, School of Engineering Sciences in Chemistry, Biotechnology and Health, Royal Institute of Technology (KTH), AlbaNova University Centre, Stockholm 10691, Sweden
| | - Hema Rajaram
- Molecular Biology Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085, India; Homi Bhabha National Institute, Anushakti Nagar, Mumbai 400094, India.
| | - Yogesh Mishra
- Department of Botany, Centre of Advanced Study in Botany, Institute of Science, Banaras Hindu University, Varanasi 221005, India.
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Pandey S, Kumar A, Kirti A, Gupta GD, Rajaram H. Rec(F/O/R) proteins of the nitrogen-fixing cyanobacterium Nostoc PCC7120: In silico and expression analysis. Gene 2021; 788:145663. [PMID: 33887372 DOI: 10.1016/j.gene.2021.145663] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2020] [Revised: 03/01/2021] [Accepted: 04/15/2021] [Indexed: 01/19/2023]
Abstract
The high radioresistance of Nostoc sp. strain PCC7120 is indicative of a robust DNA repair pathway. In the absence of NHEJ pathway and the canonical RecBCD proteins, the RecF pathway proteins are expected to play an important role in double strand break repair in this organism. The RecF, RecO and RecR proteins which are central to the RecF pathway have not been characterised in the ancient cyanobacteria, several of which are known to be radioresistant. The characterisation of these proteins was initiated through a mix of in silico, expression and complementation analysis. Differential expression of the recF, recO and recR genes was observed both at the transcript and the protein level under normal growth condition, which did not change significantly upon exposure to DNA damage stresses. Expression of RecR as a 23 kDa protein in vivo in Nostoc PCC7120 confirmed the re-annotation of the initiation codon of the gene (alr4977) to a rare initiation codon 'GTT' 267 bases upstream of the annotated initiation codon. Of the three proteins, Nostoc RecO and RecR proteins could complement the corresponding mutations in Escherichia coli, but not RecF. The Nostoc RecO protein exhibited low sequence and structural homology with other bacterial RecO protein, and was predicted to have a longer loop region. Phylogenetic as well as sequence analysis revealed high conservation among bacterial RecR proteins and least for RecO. In silico analysis revealed a comparatively smaller interactome for the Nostoc RecF, RecO and RecR proteins compared to other bacteria, with RecO predicted to interact with both RecF and RecR. The information gathered can form a stepping stone to further characterise these proteins in terms of deciphering their interactome, biochemical and physiological activities. This would help in establishing their importance in RecF pathway of DSB repair in Nostoc PCC7120.
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Affiliation(s)
- Sarita Pandey
- Cyanobacterial Stress Biology and Biotechnology Section, Molecular Biology Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085, India
| | - Arvind Kumar
- Cyanobacterial Stress Biology and Biotechnology Section, Molecular Biology Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085, India
| | - Anurag Kirti
- Cyanobacterial Stress Biology and Biotechnology Section, Molecular Biology Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085, India
| | - Gagan D Gupta
- Radiaiton Biology and Health Sciences Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085, India; Homi Bhabha National Institute, Training School Complex, Anushakti Nagar, Mumbai 400094, India
| | - Hema Rajaram
- Cyanobacterial Stress Biology and Biotechnology Section, Molecular Biology Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085, India; Homi Bhabha National Institute, Training School Complex, Anushakti Nagar, Mumbai 400094, India.
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Double strand break (DSB) repair in Cyanobacteria: Understanding the process in an ancient organism. DNA Repair (Amst) 2020; 95:102942. [DOI: 10.1016/j.dnarep.2020.102942] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2020] [Revised: 07/19/2020] [Accepted: 07/26/2020] [Indexed: 02/07/2023]
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Xing WY, Xie LR, Zeng X, Yang Y, Zhang CC. Functional Dissection of Genes Encoding DNA Polymerases Based on Conditional Mutants in the Heterocyst-Forming Cyanobacterium Anabaena PCC 7120. Front Microbiol 2020; 11:1108. [PMID: 32582078 PMCID: PMC7283527 DOI: 10.3389/fmicb.2020.01108] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2020] [Accepted: 05/04/2020] [Indexed: 01/08/2023] Open
Abstract
The filamentous cyanobacterium Anabaena sp. PCC 7120 develops N2-fixing heterocyst cells under condition of combined-nitrogen deprivation and constitutes an excellent model for studying cell differentiation. The mechanism of heterocyst development has been extensively investigated and a network of regulating factors has been identified. A few studies have showed that the process of heterocyst differentiation relates with cell cycle events, but further investigation is still required to understand this relationship. In a previous study, we created a conditional mutant of PolI encoding gene, polA, by using a CRISPR/Cpf1 gene-editing technique. Here, we were able to create another conditional mutant of a PolIII encoding gene dnaENI using a similar strategy and subsequently confirmed the essential roles of both polA and dnaENI in DNA replication. Further investigation on the phenotype of the mutants showed that lack of PolI caused defects in chromosome segregation and cell division, while lack of DnaENI (PolIII) prevented bulk DNA synthesis, causing significant loss of DNA content. Our findings also suggested the possible existence of a SOS-response like mechanism operating in Anabaena PCC 7120. Moreover, we found that heterocyst development was differently affected in the two conditional mutants, with double heterocysts/proheterocysts found in PolI conditional mutant. We further showed that formation of such double heterocysts/proheterocysts are likely caused by the difficulty in nucleoids segregation, resulting delayed, or non-complete closure of the septum between the two daughter cells. This study uncovers a link between DNA replication process and heterocyst differentiation, paving the way for further studies on the relationship between cell cycle and cell development.
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Affiliation(s)
- Wei-Yue Xing
- State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, China.,Key Laboratory of Algal Biology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, China.,University of Chinese Academy of Sciences, Beijing, China
| | - Li-Rui Xie
- State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, China.,Key Laboratory of Algal Biology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, China
| | - Xiaoli Zeng
- State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, China.,Key Laboratory of Algal Biology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, China
| | - Yiling Yang
- State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, China.,Key Laboratory of Algal Biology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, China
| | - Cheng-Cai Zhang
- State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, China.,Key Laboratory of Algal Biology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, China.,Institut WUT-AMU, Aix-Marseille Université and Wuhan University of Technology, Wuhan, China
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8
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Leaden L, Silva LG, Ribeiro RA, Dos Santos NM, Lorenzetti APR, Alegria TGP, Schulz ML, Medeiros MHG, Koide T, Marques MV. Iron Deficiency Generates Oxidative Stress and Activation of the SOS Response in Caulobacter crescentus. Front Microbiol 2018; 9:2014. [PMID: 30210482 PMCID: PMC6120978 DOI: 10.3389/fmicb.2018.02014] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2018] [Accepted: 08/09/2018] [Indexed: 01/18/2023] Open
Abstract
In C. crescentus, iron metabolism is mainly controlled by the transcription factor Fur (ferric uptake regulator). Iron-bound Fur represses genes related to iron uptake and can directly activate the expression of genes for iron-containing proteins. In this work, we used total RNA sequencing (RNA-seq) of wild type C. crescentus growing in minimal medium under iron limitation and a fur mutant strain to expand the known Fur regulon, and to identify novel iron-regulated genes. The RNA-seq of cultures treated with the iron chelator 2-2-dypiridyl (DP) allowed identifying 256 upregulated genes and 236 downregulated genes, being 176 and 204 newly identified, respectively. Sixteen transcription factors and seven sRNAs were upregulated in iron limitation, suggesting that the response to low iron triggers a complex regulatory network. Notably, lexA along with most of its target genes were upregulated, suggesting that DP treatment caused DNA damage, and the SOS DNA repair response was activated in a RecA-dependent manner, as confirmed by RT-qPCR. Fluorescence microscopy assays using an oxidation-sensitive dye showed that wild type cells in iron limitation and the fur mutant were under endogenous oxidative stress, and a direct measurement of cellular H2O2 showed that cells in iron-limited media present a higher amount of endogenous H2O2. A mutagenesis assay using the rpoB gene as a reporter showed that iron limitation led to an increase in the mutagenesis rate. These results showed that iron deficiency causes C. crescentus cells to suffer oxidative stress and to activate the SOS response, indicating an increase in DNA damage.
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Affiliation(s)
- Laura Leaden
- Departamento de Microbiologia, Instituto de Ciências Biomédicas, Universidade de São Paulo, São Paulo, Brazil
| | - Larissa G Silva
- Departamento de Microbiologia, Instituto de Ciências Biomédicas, Universidade de São Paulo, São Paulo, Brazil
| | - Rodolfo A Ribeiro
- Departamento de Microbiologia, Instituto de Ciências Biomédicas, Universidade de São Paulo, São Paulo, Brazil
| | - Naara M Dos Santos
- Departamento de Microbiologia, Instituto de Ciências Biomédicas, Universidade de São Paulo, São Paulo, Brazil
| | - Alan P R Lorenzetti
- Departamento de Bioquímica e Imunologia, Faculdade de Medicina de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, Brazil
| | - Thiago G P Alegria
- Departamento de Genética e Biologia Evolutiva, Instituto de Biociências, Universidade de São Paulo, São Paulo, Brazil
| | - Mariane L Schulz
- Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, São Paulo, Brazil
| | - Marisa H G Medeiros
- Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, São Paulo, Brazil
| | - Tie Koide
- Departamento de Bioquímica e Imunologia, Faculdade de Medicina de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, Brazil
| | - Marilis V Marques
- Departamento de Microbiologia, Instituto de Ciências Biomédicas, Universidade de São Paulo, São Paulo, Brazil
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Kumar A, Kirti A, Rajaram H. Regulation of multiple abiotic stress tolerance by LexA in the cyanobacterium Anabaena sp. strain PCC7120. BIOCHIMICA ET BIOPHYSICA ACTA. GENE REGULATORY MECHANISMS 2018; 1861:S1874-9399(18)30185-8. [PMID: 30055321 DOI: 10.1016/j.bbagrm.2018.07.007] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/02/2018] [Revised: 07/15/2018] [Accepted: 07/19/2018] [Indexed: 11/28/2022]
Abstract
The paradigm of involvement of LexA in regulation of only SOS-response in bacteria through the down-regulation of DNA repair genes was challenged in the unicellular cyanobacterium, Synechocystis PCC6803, wherein it was originally shown not to be associated with DNA repair and later also involved in management of carbon-starvation through up-regulation of C-metabolism genes. In the filamentous cyanobacterium, Anabaena sp. strain PCC7120, global stress management role for LexA and a consensus LexA-binding box (AnLexA-box) has been established using a LexA-overexpressing recombinant strain, AnlexA+. High levels of LexA rendered Anabaena cells sensitive to different DNA damage and oxidative stress-inducing agents, through the transcriptional down-regulation of the genes involved in DNA repair and alleviation of oxidative stress. LexA overexpression enhanced the ability of Anabaena to tolerate C-depletion, induced by inhibiting photosynthesis, by up-regulating genes involved in C-fixation and down-regulating those involved in C-breakdown, while maintaining the overall photosynthetic efficiency. A consensus LexA-binding box, AnLexA-box [AGT-N4-11-ACT] was identified upstream of both up- and down-regulated genes using a subset of Anabaena genes identified on the basis of proteomic analysis of AnlexA+ strain along with a few DNA repair genes. A short genome search revealed the presence of AnLexA box in at least 40 more genes, with functional roles in fatty acid biosynthesis, toxin-antitoxin systems in addition to DNA repair, oxidative stress, metal tolerance and C-metabolism. Thus, Anabaena LexA modulates the tolerance to multitude of stresses through transcriptional up/down-regulation of their functional genes directly by binding to the AnLexA Box present in their promoter region.
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Affiliation(s)
- Arvind Kumar
- Molecular Biology Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085, India; Homi Bhabha National Institute, Training School Complex, Anushakti Nagar, Trombay, Mumbai 400094, India
| | - Anurag Kirti
- Molecular Biology Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085, India
| | - Hema Rajaram
- Molecular Biology Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085, India; Homi Bhabha National Institute, Training School Complex, Anushakti Nagar, Trombay, Mumbai 400094, India.
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Pandey S, Kirti A, Kumar A, Rajaram H. The SbcC and SbcD homologs of the cyanobacterium Anabaena sp. strain PCC7120 (Alr3988 and All4463) contribute independently to DNA repair. Funct Integr Genomics 2018. [DOI: 10.1007/s10142-018-0599-7] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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