Phosphoproteome modulation by nucleoside diphosphate kinase affects photosynthesis & stress tolerance of Nostoc PCC 7120.

Nucleoside diphosphate kinase (Ndk/NDK/NDPK) is known to possess pleiotropic functions, one of which is that as a protein kinase, and has been shown to be involved in stress tolerance in plants. To assess its role in the cyanobacterium Nostoc PCC 7120, which is hitherto unreported, recombinant strain overexpressing Ndk, Anndk was generated. Phosphoproteomic analysis of Anndk and its comparison with that of the vector control, AnpAM, revealed differential phosphorylation at S/T/Y sites of proteins belonging to varied functional groups, with over 17 % phosphoproteins involved in photosynthesis.

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

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.

Thymidylate kinase (TMK) of the photosynthetic, nitrogen-fixing cyanobacterium Nostoc sp. strain PCC7120: Biophysical, biochemical and physiological characterisation.

Thymidylate kinase (TMK/TMPK) is an important enzyme in DNA biosynthesis and catalyses the conversion of dTMP to dTDP. Due to its therapeutic potential, the focus has been on characterizing the TMK proteins of pathogens and human origin, with very little information available on the TMK proteins of photosynthetic organisms and agriculturally important nitrogen-fixing organisms. In this work we report the characterisation of TMK in an evolutionarily ancient organism, cyanobacteria.

Rec(F/O/R) proteins of the nitrogen-fixing cyanobacterium Nostoc PCC7120: In silico and expression analysis.

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.

Double strand break (DSB) repair in Cyanobacteria: Understanding the process in an ancient organism.

Cyanobacterial species, Anabaena/Nostoc and Chroococcidiopsis are highly radio-resistant indicating the presence of a robust DNA repair system. However, unlike the establishment of multiple DNA repair pathways in the radio-resistant Deinococcus, research on DNA repair in cyanobacteria has lagged far behind. Being ancient organisms, it is likely that the DNA repair mechanisms have evolved from cyanobacteria to the modern day bacteria.

Regulation of multiple abiotic stress tolerance by LexA in the cyanobacterium Anabaena sp. strain PCC7120.

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.

The SbcC and SbcD homologs of the cyanobacterium Anabaena sp. strain PCC7120 (Alr3988 and All4463) contribute independently to DNA repair.

The ubiquitous SbcCD exonuclease complex has been shown to perform an important role in DNA repair across prokaryotes and eukaryotes. However, they have remained uncharacterized in the ancient and stress-tolerant cyanobacteria. In the cyanobacterium Anabaena sp.

Differential regulation of ssb genes in the nitrogen-fixing cyanobacterium, Anabaena sp. strain PCC7120.

Anabaena sp. PCC7120 possesses three genes coding for single-stranded DNA-binding (SSB) protein, of which ssb1 was a single gene, and ssb2 and ssb3 are the first genes of their corresponding operons. Regulation of the truncated ssb genes, ssb1 (alr0088) and ssb2 (alr7559), was unaffected by N-status of growth.

LexA protein of cyanobacterium Anabaena sp. strain PCC7120 exhibits in vitro pH-dependent and RecA-independent autoproteolytic activity.

The LexA protein of the nitrogen-fixing cyanobacterium, Anabaena sp. strain PCC7120 exhibits a RecA-independent and alkaline pH-dependent autoproteolytic cleavage. The autoproteolytic cleavage of Anabaena LexA occurs at pH 8.

The hypothetical protein 'All4779', and not the annotated 'Alr0088' and 'Alr7579' proteins, is the major typical single-stranded DNA binding protein of the cyanobacterium, Anabaena sp. PCC7120.

Single-stranded DNA binding (SSB) proteins are essential for all DNA-dependent cellular processes. Typical SSB proteins have an N-terminal Oligonucleotide-Binding (OB) fold, a Proline/Glycine rich region, followed by a C-terminal acidic tail. In the genome of the heterocystous nitrogen-fixing cyanobacterium, Anabaena sp.

High radiation and desiccation tolerance of nitrogen-fixing cultures of the cyanobacterium Anabaena sp. strain PCC 7120 emanates from genome/proteome repair capabilities.

The filamentous nitrogen-fixing cyanobacterium, Anabaena sp. strain PCC 7120 was found to tolerate very high doses of Co-gamma radiation or prolonged desiccation. Post-stress, cells remained intact and revived all the vital functions.

Characterization of two naturally truncated, Ssb-like proteins from the nitrogen-fixing cyanobacterium, Anabaena sp. PCC7120.

Single-stranded (ss) DNA-binding (Ssb) proteins are vital for all DNA metabolic processes and are characterized by an N-terminal OB-fold followed by P/G-rich spacer region and a C-terminal tail. In the genome of the heterocystous, nitrogen-fixing cyanobacterium, Anabaena sp. strain PCC 7120, two genes alr0088 and alr7579 are annotated as ssb, but the corresponding proteins have only the N-terminal OB-fold and no P/G-rich region or acidic tail, thereby rendering them unable to interact with genome maintenance proteins.