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Single stranded binding protein
From Proteopedia
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==Introduction== | ==Introduction== | ||
| - | The single-stranded DNA-binding protein (SSB) of Escherichia coli is involved in all aspects of DNA metabolism: replication, repair, and recombination. | ||
| - | In solution, the protein exists as a homotetramer of 18,843-kilodalton subunits. As it binds tightly and cooperatively to single-stranded DNA, it has become | ||
| - | a prototypic model protein for studying protein-nucleic acid interactions. The sequences of the gene and protein are known, and the functional domains of | ||
| - | subunit interaction, DNA binding, and protein-protein interactions have been probed by structure-function analyses of various mutations. The ssb gene has | ||
| - | three promoters, one of which is inducible because it lies only two nucleotides from the LexA-binding site of the adjacent uvrA gene. Induction of the SOS | ||
| - | response, however, does not lead to significant increases in SSB levels. The binding protein has several functions in DNA replication, including enhancement | ||
| - | of helix destabilization by DNA helicases, prevention of reannealing of the single strands and protection from nuclease digestion, organization and stabilization | ||
| - | of replication origins, primosome assembly, priming specificity, enhancement of replication fidelity, enhancement of polymerase processivity, and promotion | ||
| - | of polymerase binding to the template. E. coli SSB is required for methyl-directed mismatch repair, induction of the SOS response, and recombinational repair. | ||
| - | During recombination, SSB interacts with the RecBCD enzyme to find Chi sites, promotes binding of RecA protein, and promotes strand uptake. | ||
Copies of SSB bind to the unwound DNA strands, keeping the strands separated so that both strands can serve as templates. | Copies of SSB bind to the unwound DNA strands, keeping the strands separated so that both strands can serve as templates. | ||
Revision as of 15:55, 30 October 2013
Sandbox Single Stranded DNA-Binding Protein (SSB)
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Proteopedia Page Contributors and Editors (what is this?)
Refayat Ahsen, Rachel Craig, Michal Harel, Alexander Berchansky
