ssbA

168

single-strand DNA-binding protein, part of the replisome, promoter of RecA DNA repair center assembly, required to internalize and to recombine ssDNA with homologous resident duplex

Locus: BSU_40900

Molecular weight: 18.60 kDa

Isoelectric point: 4.82

Protein length: 172 aa

Gene length: 519 bp

Function: DNA replication, DNA repair/ recombination

Product: single-strand DNA-binding protein

Essential: yes

Synonyms: ssbA, ssb

Genomic Context

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List of homologs in different organisms, belongs to COG0629 (Galperin et al., 2021)

Gene

Coordinates: 4,198,886  4,199,404

Phenotypes of a mutant

• essential PubMed

The protein

Catalyzed reaction/ biological activity

• SsbA inhibits ssDNA phosphorylase activity of PnpA PubMed
• SsbA co-assembles onto SsbB-coated ssDNA PubMed
• important for RecA DNA repair center assembly by recruiting RecO and RecR to the replisome PubMed
• RecA-ATP in concert with DprA and SsbA catalyzes DNA strand exchange, with SsbB as an accessory factor PubMed
• inhibits stable RecA nucleation and polymerization on ssDNA PubMed
• the SsbA-DprA mediator loads RecA onto any fragmented linear SPP1 ssDNAPubMed

Domains

• SSB domain (aa 1-104) (according to UniProt)

Structure

• 6BHX (PDB) (complex with ssDNA) PubMed
• 6BHW (PDB) PubMed
• P37455 (AlphaFold)

Modification

• phosphorylated on Arg-76 PubMed
• phosphorylated on Tyr-82 by PtkA, dephosphorylated by PtpZ PubMed

Effectors of protein activity

• Phosphorylation of Ssb increases binding to single-stranded DNA in vitro almost 200-fold PubMed

Paralogous protein(s)

• SsbB

Localization

• forms foci PubMed
• Nucleoid (Mid-cell) PubMed

Expression and Regulation

Operons

• Genes: yyzM-yyaE-yyaF-rpsF-ssbA-rpsR

  Description: PubMed

• Genes: yyaF-rpsF-ssbA-rpsR

  Description: PubMed

  Regulation

  • ComK: transcription activation PubMed

  Regulatory mechanism

  • ComK: activation, in comK regulon
  • stringent response: negative regulation, in stringent response

  Sigma factors

  • SigA: sigma factor, PubMed, in sigA regulon

• Genes: rpsF-ssbA-rpsR

  Description: PubMed

  Regulation

  • ComK: transcription activation PubMed

Biological materials

Two-hybrid system

• B. pertussis adenylate cyclase-based bacterial two hybrid system (BACTH), available in Fabian Commichau's lab

References

Reviews

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Original Publications

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