Regulatory role of LexA in modulating photosynthetic redox poise and cadmium stress tolerance in the cyanobacterium, Anabaena sp. PCC7120

Srivastava, Akanksha; Kumar, Arvind; Biswas, Subhankar; Srivastava, Vaibhav; Rajaram, Hema; Mishra, Yogesh

doi:10.1016/j.envexpbot.2022.104790

Cited by 9 publications

(41 citation statements)

References 77 publications

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“…Sequence analysis of P recF , P recO and P recR fragments revealed the presence of (i) two promoter elements, predicted using the BPROM software (http://www.softberry.com/berry, 45), designated as PI and PII in P recF and P recR and one (P) in P recO , (ii) two AnLexA-boxes based on the earlier defined consensus sequence (27,32), AnLexA-Box1 and AnLexA-Box2 in all three, with AnLexA-Box1 corresponding to the one identified earlier (5), (iii) NtcA-like boxes, based on the earlier defined consensus sequence (31), two upstream of recR and one each upstream of recF and recO , and (iv) two distinct heptamer repeats in P recF and P recO (Figs. 1C, S1).…”

Section: Resultsmentioning

confidence: 99%

“…In Anabaena PCC7120, ChIP Seq analysis revealed 2424 putative DNA regions of which 865 were in the promoter regions corresponding to a wide NtcA binding site defined mostly as GT-N 10 -AC, but also included a few wherein either only the left arm (GTA) or the right arm (TAC) is conserved, provided the end bases are invariant G and C and spacing between ‘G’ and ‘C’ is 12 (31). The well-known SOS-response regulator LexA transcriptionally regulates several genes beyond those involved in DNA repair through binding to the AnLexA-Box [AGT-N 4-11 -ACT] allowing for one base mismatch in case of a 4-base palindrome (27,32). In fact, in the unicellular cyanobacteria, Synechocystis PCC6803, LexA has been shown to regulate genes involved in C-metabolism but not those in DNA repair (33,34).…”

Section: Introductionmentioning

confidence: 99%

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NtcA, LexA and heptamer repeats involved in the multifaceted regulation of DNA repair genes recF, recO and recR in the cyanobacterium Nostoc PCC7120

Pradhan

Kumar

Kirti

et al. 2022

Preprint

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Regulation of DNA repair genes in cyanobacteria is an unexplored field despite some of them exhibit high radio-resistance. With the RecF pathway speculated to be the major double strand break repair pathway in Nostoc sp. strain PCC7120, the 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 on the involvement of NtcA and heptamer repeats in regulation of DNA repair genes in any organism.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

NtcA, LexA and heptamer repeats involved in the multifaceted regulation of DNA repair genes recF, recO and recR in the cyanobacterium Nostoc PCC7120

Pradhan

Kumar

Kirti

et al. 2022

Preprint

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“…The copyright holder for this this version posted September 23, 2022. ; https://doi.org/10.1101/2022.09.23.509143 doi: bioRxiv preprint al., 2017; Kumar et al, 2018;Pandey et al, 2018;Pradhan et al, 2022 PREPRINT), oxidative stress-alleviating and C-metabolism genes (Kumar et al, 2018), photosynthetic electron transport chain (pETC) components (Srivastava et al, 2022a), and a few γ-radiation response genes (Srivastava et al, 2022b PREPRINT). The global regulatory role of LexA, both as an activator and a repressor, may be the reason for the non-viable nature of the lexA mutant of Anabaena (Kumar et al, 2018).…”

Section: Introductionmentioning

confidence: 99%

“…On the other hand, LexA of Anabaena sp. PCC7120 (hereinafter referred to as Anabaena ), exhibited RecA-independent but pH-dependent cleavage (Kumar et al, 2015), and was found to function as a global regulator for genes belonging to several functional categories (Mazón et al, 2004; Sjöholm et al, 2007; Kirti et al, 2017; Kumar et al, 2018; Pandey et al, 2018; Rajaram et al, 2022; Pradhan et al, 2022 PREPRINT; Srivastava et al, 2022a; Srivastava et al, 2022b PREPRINT). The regulation by LexA in Anabaena was through binding to the AnLexA-Box defined as AGT-N 4-11 -ACT with one base mismatch allowed within a 4-base palindrome (Kumar et al, 2018; Srivastava et al, 2022a).…”

Section: Introductionmentioning

confidence: 99%

“…PCC7120 (hereinafter referred to as Anabaena ), exhibited RecA-independent but pH-dependent cleavage (Kumar et al, 2015), and was found to function as a global regulator for genes belonging to several functional categories (Mazón et al, 2004; Sjöholm et al, 2007; Kirti et al, 2017; Kumar et al, 2018; Pandey et al, 2018; Rajaram et al, 2022; Pradhan et al, 2022 PREPRINT; Srivastava et al, 2022a; Srivastava et al, 2022b PREPRINT). The regulation by LexA in Anabaena was through binding to the AnLexA-Box defined as AGT-N 4-11 -ACT with one base mismatch allowed within a 4-base palindrome (Kumar et al, 2018; Srivastava et al, 2022a). The binding has been shown for a few DNA repair genes (Kirti et al, 2017; Kumar et al, 2018; Pandey et al, 2018; Pradhan et al, 2022 PREPRINT), oxidative stress-alleviating and C-metabolism genes (Kumar et al, 2018), photosynthetic electron transport chain (pETC) components (Srivastava et al, 2022a), and a few γ-radiation response genes (Srivastava et al, 2022b PREPRINT).…”

Section: Introductionmentioning

confidence: 99%

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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

Srivastava

Kumar

Biswas

et al. 2022

Preprint

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LexA, a well-characterized transcriptional repressor of the 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, in light of 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 stress tolerance, with regulation over a variety of Cd stress-responsive genes in addition to the regulation on genes related with photosynthetic redox poising. 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, carbon metabolism, antioxidative defence, protein turnover, chaperones, post-transcriptional modifications, and a few unknown and hypothetical proteins. The regulation of LexA on corresponding genes, as well as 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 LexA on several genes and proteins of various functional categories in Anabaena that are responsive to Cd stress, hence expanding the regulatory role of LexA under Cd stress.

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NtcA, LexA and heptamer repeats involved in the multifaceted regulation of DNA repair genes recF, recO and recR in the cyanobacterium Nostoc PCC7120

Pradhan

Kumar

Kirti

et al. 2023

Biochimica et Biophysica Acta (BBA) - Gene Regulatory Mechanism

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Regulatory role of LexA in modulating photosynthetic redox poise and cadmium stress tolerance in the cyanobacterium, Anabaena sp. PCC7120

Cited by 9 publications

References 77 publications

NtcA, LexA and heptamer repeats involved in the multifaceted regulation of DNA repair genes recF, recO and recR in the cyanobacterium Nostoc PCC7120

NtcA, LexA and heptamer repeats involved in the multifaceted regulation of DNA repair genes recF, recO and recR in the cyanobacterium Nostoc PCC7120

Cd-induced cytosolic proteome changes in the cyanobacterium Anabaena sp. PCC7120 are mediated by LexA as one of the regulatory proteins

NtcA, LexA and heptamer repeats involved in the multifaceted regulation of DNA repair genes recF, recO and recR in the cyanobacterium Nostoc PCC7120

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