Previous Article | Next Article 
Journal of Bacteriology, May 2004, p. 2774-2780, Vol. 186, No. 9
0021-9193/04/$08.00+0 DOI: 10.1128/JB.186.9.2774-2780.2004
The
Subunit of Escherichia coli DNA Polymerase III: a Role in Stabilizing the
Proofreading Subunit
Sharon A. Taft-Benz
and Roel M. Schaaper*
Laboratory of Molecular Genetics, National Institute of Environmental Health Sciences, Research Triangle Park, North Carolina 27709
Received 18 December 2003/
Accepted 16 January 2004
The function of the
subunit of Escherichia coli DNA polymerase III holoenzyme is not well established.
is a tightly bound component of the DNA polymerase III core, which contains the
subunit (polymerase), the
subunit (3'
5' exonuclease), and the
subunit, in the linear order
-
-
. Previous studies have shown that the
subunit is not essential, as strains carrying a deletion of the holE gene (which encodes
) proved fully viable. No significant phenotypic effects of the holE deletion could be detected, as the strain displayed normal cell health, morphology, and mutation rates. On the other hand, in vitro experiments have indicated the efficiency of the 3'-exonuclease activity of
to be modestly enhanced by the presence of
. Here, we report a series of genetic experiments that suggest that
has a stabilizing role for the
proofreading subunit. The observations include (i) defined
holE mutator effects in mismatch-repair-defective mutL backgrounds, (ii) strong
holE mutator effects in certain proofreading-impaired dnaQ strains, and (iii) yeast two- and three-hybrid experiments demonstrating enhancement of
-
interactions by the presence of
.
appears conserved among gram-negative organisms which have an exonuclease subunit that exists as a separate protein (i.e., not part of the polymerase polypeptide), and the presence of
might be uniquely beneficial in those instances where the proofreading 3'-exonuclease is not part of the polymerase polypeptide.
* Corresponding author. Mailing address: NIEHS, Laboratory of Molecular Genetics, MD E3-01, P.O. Box 12233, 111 T. W. Alexander Dr., Research Triangle Park, NC 27709. Phone: (919) 541-4250. Fax: (919) 541-7613. E-mail: schaaper{at}niehs.nih.gov.
Present address: Department of Microbiology and Immunology, University of North Carolina, Chapel Hill, NC 27599.
Journal of Bacteriology, May 2004, p. 2774-2780, Vol. 186, No. 9
0021-9193/04/$08.00+0 DOI: 10.1128/JB.186.9.2774-2780.2004
This article has been cited by other articles:
-
Ozawa, K., Jergic, S., Park, A. Y., Dixon, N. E., Otting, G.
(2008). The proofreading exonuclease subunit {varepsilon} of Escherichia coli DNA polymerase III is tethered to the polymerase subunit {alpha} via a flexible linker. Nucleic Acids Res
36: 5074-5082
[Abstract]
[Full Text]
-
Gawel, D., Pham, P. T., Fijalkowska, I. J., Jonczyk, P., Schaaper, R. M.
(2008). Role of Accessory DNA Polymerases in DNA Replication in Escherichia coli: Analysis of the dnaX36 Mutator Mutant. J. Bacteriol.
190: 1730-1742
[Abstract]
[Full Text]
-
Jergic, S., Ozawa, K., Williams, N. K., Su, X.-C., Scott, D. D., Hamdan, S. M., Crowther, J. A., Otting, G., Dixon, N. E.
(2007). The unstructured C-terminus of the {tau} subunit of Escherichia coli DNA polymerase III holoenzyme is the site of interaction with the {alpha} subunit. Nucleic Acids Res
35: 2813-2824
[Abstract]
[Full Text]
-
Kirby, T. W., Harvey, S., DeRose, E. F., Chalov, S., Chikova, A. K., Perrino, F. W., Schaaper, R. M., London, R. E., Pedersen, L. C.
(2006). Structure of the Escherichia coli DNA Polymerase III {epsilon}-HOT Proofreading Complex. J. Biol. Chem.
281: 38466-38471
[Abstract]
[Full Text]
-
Chikova, A. K., Schaaper, R. M.
(2006). Mutator and Antimutator Effects of the Bacteriophage P1 hot Gene Product.. J. Bacteriol.
188: 5831-5838
[Abstract]
[Full Text]
-
Keniry, M. A., Park, A. Y., Owen, E. A., Hamdan, S. M., Pintacuda, G., Otting, G., Dixon, N. E.
(2006). Structure of the {theta} Subunit of Escherichia coli DNA Polymerase III in Complex with the {varepsilon} Subunit.. J. Bacteriol.
188: 4464-4473
[Abstract]
[Full Text]
-
Mueller, G. A., Kirby, T. W., DeRose, E. F., Li, D., Schaaper, R. M., London, R. E.
(2005). Nuclear Magnetic Resonance Solution Structure of the Escherichia coli DNA Polymerase III {theta} Subunit. J. Bacteriol.
187: 7081-7089
[Abstract]
[Full Text]
-
Chikova, A. K., Schaaper, R. M.
(2005). The Bacteriophage P1 hot Gene Product Can Substitute for the Escherichia coli DNA Polymerase III {theta} Subunit. J. Bacteriol.
187: 5528-5536
[Abstract]
[Full Text]
Copyright © 2004 by the American Society for Microbiology. All rights reserved.