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Protein FULL name:
DNA polymerase IV
Protein SHORT name:
DinB (Escherichia coli strain K-12 substr. MG1655) is product of expression of dinB gene.
DinB is involved in:
TLS in Escherichia coli strain K-12 substr. MG1655
FUNCTION: Poorly processive, error-prone DNA polymerase involved in untargeted mutagenesis. Copies undamaged DNA at stalled replication forks, which arise in vivo from mismatched or misaligned primer ends. These misaligned primers can be extended by polIV. Exhibits no 3'-5' exonuclease (proofreading) activity. Overexpression of polIV results in increased frameshift mutagenesis. It is required for stationary-phase adaptive mutation, which provides the bacterium with flexibility in dealing with environmental stress, enhancing long-term survival and evolutionary fitness. May be involved in translesional synthesis, in conjunction with the beta clamp from polIII.
CATALYTIC ACTIVITY: Deoxynucleoside triphosphate + DNA(n) = diphosphate + DNA(n+1).
COFACTOR: Binds 2 magnesium ions per subunit (By similarity).
SUBUNIT: Monomer (Potential).
SUBCELLULAR LOCATION: Cytoplasm (Probable).
INDUCTION: By SOS response.
DOMAIN: The catalytic core consists of fingers, palm and thumb subdomains, but the fingers and thumb subdomains are much smaller than in high-fidelity polymerases; residues from five sequence motifs of the Y-family cluster around an active site cleft that can accommodate DNA and nucleotide substrates with relaxed geometric constraints, with consequently higher rates of misincorporation and low processivity. It lacks the O helices present in high-fidelity DNA polymerases in the fingers domain (By similarity).
SIMILARITY: Belongs to the DNA polymerase type-Y family.
SIMILARITY: Contains 1 umuC domain.
Links to other databases:
Last modification of this entry: Oct. 15, 2010.
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