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Mutant forms of the Escherichia coli β sliding clamp that distinguish between its roles in replication and DNA polymerase V‐dependent translesion DNA synthesis
Author(s) -
Sutton Mark D.,
Duzen Jill M.,
Maul Robert W.
Publication year - 2005
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1111/j.1365-2958.2005.04500.x
Subject(s) - dna polymerase , biology , processivity , dna clamp , dna replication , dna polymerase delta , dna polymerase ii , mutant , polymerase , dna polymerase i , dna polymerase beta , prokaryotic dna replication , clamp , microbiology and biotechnology , dna synthesis , dna , dna repair , biophysics , genetics , circular bacterial chromosome , gene , base excision repair , polymerase chain reaction , mechanical engineering , reverse transcriptase , clamping , engineering
Summary The Escherichia coli β sliding clamp is proposed to play an important role in regulating DNA polymerase traffic at the replication fork. As part of an ongoing effort to understand how organisms manage the actions of their multiple DNA polymerases, we examined the ability of several mutant forms of the β clamp to function in DNA polymerase V‐ (pol V‐) dependent translesion DNA synthesis (TLS) in vivo . Our results indicate that a dnaN159 strain, which expresses a temperature sensitive form of the β clamp, was impaired for pol V‐dependent TLS at the permissive temperature of 37°C. This defect was complemented by a plasmid that expressed near‐physiological levels of the wild‐type clamp. Using a dnaN159 mutant strain, together with various plasmids expressing mutant forms of the clamp, we determined that residues H148 through R152, which comprise a portion of a solvent exposed loop, as well as position P363, which is located in the C‐terminal tail of the β clamp, are critically important for pol V‐dependent TLS in vivo . In contrast, these same residues appear to be less critical for pol III‐dependent replication. Taken together, these findings indicate that: (i) the β clamp plays an essential role in pol V‐dependent TLS in vivo and (ii) pol III and pol V interact with non‐identical surfaces of the β clamp.