D
IPR012339

Bacteriophage T4, Gp32, single-stranded DNA-binding domain

InterPro entry
Short namePhage_T4_Gp32_ssDNA-bd
Overlapping
homologous
superfamilies
 

Description

This entry represents the Bacteriophage T4, Gp32, single-stranded DNA-binding domain. The characteristics of the protein distribution suggest prophage matches in addition to the phage matches.

Single-stranded DNA-binding protein (also known as Gp32 or SSB) is essential for bacteriophage T4 DNA replication, recombination and repair, acting to stimulate replisome processing and accuracy through its binding to ssDNA as the replication fork advances
[2]
. The crystal structure of Gp32 shows an ssDNA binding cleft comprised of regions from three structural subdomains, through which ssDNA can slide freely
[1]
. The structure of Gp32 is similar to other phage ssDNA-binding proteins such as Gp2.5 from bacteriophage T4, and gene V protein, both of which have a nucleic acid-binding OB-type fold. However, Gp32 contains a zinc-finger subdomain at residues 63-111 that is not found in the other two phage proteins.

This protein stimulates the activities of viral DNA polymerase and DnaB-like SF4 replicative helicase, probably via its interaction with the helicase assembly factor
[4]
, and together with DnaB-like SF4 replicative helicase and the helicase assembly factor, promotes pairing of two homologous DNA molecules containing complementary single-stranded regions and mediates homologous DNA strand exchange
[3]
.

References

1.Crystal structure of a replication fork single-stranded DNA binding protein (T4 gp32) complexed to DNA. Shamoo Y, Friedman AM, Parsons MR, Konigsberg WH, Steitz TA. Nature 376, 362-6, (1995). View articlePMID: 7630406

2.Role of the bacteriophage T7 and T4 single-stranded DNA-binding proteins in the formation of joint molecules and DNA helicase-catalyzed polar branch migration. Kong D, Nossal NG, Richardson CC. J Biol Chem 272, 8380-7, (1997). PMID: 9079662

3.Mediator proteins orchestrate enzyme-ssDNA assembly during T4 recombination-dependent DNA replication and repair. Bleuit JS, Xu H, Ma Y, Wang T, Liu J, Morrical SW. Proc Natl Acad Sci U S A 98, 8298-305, (2001). PMID: 11459967

4.Dual functions of single-stranded DNA-binding protein in helicase loading at the bacteriophage T4 DNA replication fork. Ma Y, Wang T, Villemain JL, Giedroc DP, Morrical SW. J Biol Chem 279, 19035-45, (2004). PMID: 14871889

GO terms

biological process

  • None

cellular component

  • None
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