SsbA

• Description: 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
  
  

Gene name	ssbA
Synonyms	ssb
Essential	yes PubMed
Product	single-strand DNA-binding protein
Function	DNA replication, DNA repair/ recombination
Gene expression levels in SubtiExpress: ssbA
Interactions involving this protein in SubtInteract: SsbA
MW, pI	18 kDa, 4.822
Gene length, protein length	516 bp, 172 aa
Immediate neighbours	rpsR, rpsF
Sequences	Protein DNA DNA_with_flanks
Genetic context This image was kindly provided by SubtiList
Expression at a glance   PubMed

Categories containing this gene/protein

DNA replication, DNA repair/ recombination, essential genes, phosphoproteins

This gene is a member of the following regulons

ComK regulon, stringent response

The gene

Basic information

• Locus tag: BSU40900

Phenotypes of a mutant

essential PubMed

Database entries

• BsubCyc: BSU40900

• DBTBS entry: [1]

• SubtiList entry: [2]

The protein

Basic information/ Evolution

• 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

• Protein family:

• Paralogous protein(s): SsbB

Extended information on the protein

• Kinetic information:

• Domains:

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

• Cofactors:

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

• Interactions:
  • forms tetramers PubMed
  • part of the replisome: PolC-HolA-HolB-DnaX-DnaN-DnaG-DnaC-DnaI-DnaD-SsbA-DnaE-PriA-DnaB PubMed
  • SsbA-SbcC PubMed
  • SsbA-RecG PubMed
  • SsbA-YrvE PubMed
  • SsbA-YrvN PubMed
  • SsbA (bound to ssDNA) -RecO, this helps to dislodge SsbA and SsbB from ssDNA PubMed
  • SsbA-YqiB PubMed
  • SsbA-Ung PubMed
  • SsbA-YpbB PubMed
  • SsbA-RecD2 PubMed
  • SsbA-DnaN PubMed
  • SsbA (bound to ssDNA) -RecO, this helps to dislodge SsbA and SsbB from ssDNA PubMed
  • SsbA-YocI according to PubMed
  • SsbA-RecQ according to PubMed

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

Database entries

• BsubCyc: BSU40900

• Structure: 3VDY 3VDY (SsbB in complex with ssDNA, 63% identity, 87% similarity) PubMed

• UniProt: P37455

• KEGG entry: [3]

• E.C. number:

Expression and regulation

• Operon:
  • yyaF-rpsF-ssbA-rpsR PubMed
  • rpsF-ssbA-rpsR PubMed

• Expression browser: ssbA PubMed

• Sigma factor:
  • rpsF: SigA PubMed

• Regulation:
  • RelA dependent downregulation (Class I) during stringent response PubMed
  • ComK: transcription activation PubMed

• Additional information:
  • the mRNA contains a structured motif in the 5' UTR upstream of the rpsF ORF that is bound by RpsF-RpsR heterodimers and may be implicated in autogenous regulation PubMed
  • number of protein molecules per cell (minimal medium with glucose and ammonium): 279 PubMed
  • number of protein molecules per cell (complex medium with amino acids, without glucose): 2199 PubMed
  • number of protein molecules per cell (minimal medium with glucose and ammonium, exponential phase): 263 PubMed
  • number of protein molecules per cell (minimal medium with glucose and ammonium, early stationary phase after glucose exhaustion): 147 PubMed
  • number of protein molecules per cell (minimal medium with glucose and ammonium, late stationary phase after glucose exhaustion): 3701 PubMed

Biological materials

• Mutant:

• Expression vector:

• lacZ fusion:

• GFP fusion:

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

• Antibody:

References

Reviews

Dusica Vujaklija, Boris Macek
Detecting posttranslational modifications of bacterial SSB proteins.
Methods Mol Biol: 2012, 922;205-18
[PubMed:22976189] [WorldCat.org] [DOI] (I p)

Justin S Lenhart, Jeremy W Schroeder, Brian W Walsh, Lyle A Simmons
DNA repair and genome maintenance in Bacillus subtilis.
Microbiol Mol Biol Rev: 2012, 76(3);530-64
[PubMed:22933559] [WorldCat.org] [DOI] (I p)