PMID:20375019
| Citation |
Ghosh, S, Hamdan, SM and Richardson, CC (2010) Two modes of interaction of the single-stranded DNA-binding protein of bacteriophage T7 with the DNA polymerase-thioredoxin complex. J. Biol. Chem. 285:18103-12 |
|---|---|
| Abstract |
The DNA polymerase encoded by bacteriophage T7 has low processivity. Escherichia coli thioredoxin binds to a segment of 76 residues in the thumb subdomain of the polymerase and increases the processivity. The binding of thioredoxin leads to the formation of two basic loops, loops A and B, located within the thioredoxin-binding domain (TBD). Both loops interact with the acidic C terminus of the T7 helicase. A relatively weak electrostatic mode involves the C-terminal tail of the helicase and the TBD, whereas a high affinity interaction that does not involve the C-terminal tail occurs when the polymerase is in a polymerization mode. T7 gene 2.5 single-stranded DNA-binding protein (gp2.5) also has an acidic C-terminal tail. gp2.5 also has two modes of interaction with the polymerase, but both involve the C-terminal tail of gp2.5. An electrostatic interaction requires the basic residues in loops A and B, and gp2.5 binds to both loops with similar affinity as measured by surface plasmon resonance. When the polymerase is in a polymerization mode, the C terminus of gene 2.5 protein interacts with the polymerase in regions outside the TBD. gp2.5 increases the processivity of the polymerase-helicase complex during leading strand synthesis. When loop B of the TBD is altered, abortive DNA products are observed during leading strand synthesis. Loop B appears to play an important role in communication with the helicase and gp2.5, whereas loop A plays a stabilizing role in these interactions. |
| Links |
PubMed PMC2878571 Online version:10.1074/jbc.M110.107656 |
| Keywords |
Bacteriophage T7/metabolism; DNA-Binding Proteins/chemistry; DNA-Binding Proteins/genetics; DNA-Directed DNA Polymerase/chemistry; Escherichia coli/metabolism; Kinetics; Lysine/chemistry; Models, Molecular; Molecular Conformation; Protein Binding; Protein Structure, Tertiary; Recombinant Proteins/chemistry; Static Electricity; Surface Plasmon Resonance; Thioredoxins/chemistry |
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