The carboxyl terminus of the bacteriophage T4 DNA polymerase contacts its sliding clamp at the subunit interface

Stephen C. Alley, A. Daniel Jones, Patrice Soumillion, Stephen J. Benkovic

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24 Scopus citations

Abstract

The location of the interaction of the COOH terminus of the bacteriophage T4 DNA polymerase with its trimeric, circular sliding clamp has been established. A peptide corresponding to the COOH terminus of the DNA polymerase was labeled with a fluorophore and fluorescence spectroscopy used to show that it forms a specific complex with the sliding clamp by virtue of its low K(D) value (7.1 ± 1.0 μM). The same peptide was labeled with a photoaffinity probe and cross-linked to the sliding clamp. Mass spectrometry of tryptic digests determined the sole linkage point to be Ala-159 on the sliding clamp, an amino acid that lies on the subunit interface. These results demonstrate that the COOH terminus of the DNA polymerase is inserted into the subunit interface of its sliding clamp, thereby conferring processivity to the DNA polymerase.

Original languageEnglish (US)
Pages (from-to)24485-24489
Number of pages5
JournalJournal of Biological Chemistry
Volume274
Issue number35
DOIs
StatePublished - Aug 27 1999

All Science Journal Classification (ASJC) codes

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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