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Journal of Bacteriology, May 1999, p. 2782-2788, Vol. 181, No. 9
Department of Microbiology and Molecular
Genetics, Oklahoma State University, Stillwater, Oklahoma 74078
Received 16 November 1998/Accepted 24 February 1999
Streptococcus pneumoniae Rx1 is capable of repairing
lesions caused by DNA-damaging agents in an error-free manner but lacks a UV-inducible error-prone repair system due to the absence of chromosomally encoded UmuDC-like proteins. We have identified an
operon-like structure 8 kb from the left end of the pneumococcal conjugative transposon Tn5252 that confers SOS function in
the host cells. DNA sequence analysis of this region revealed the presence of four open reading frames (ORFs). The deduced amino acid
sequence of one of them, ORF13, which is capable of encoding a protein
of 49.7 kDa, showed significant homology to UmuC, MucB, and other
proteins involved in the SOS response. The carboxy-terminal region of
another, ORF14, which is predicted to encode a 26-kDa polypeptide,
shared similarity with UmuD- and MucA-like proteins that carry the
amino acid residues recognized by the activated RecA* protein for
proteolytic cleavage. The presence of plasmids carrying subcloned DNA
from this region was found to restore UV-inducible mutagenic repair of
chromosomal DNA in Escherichia coli cells defective in
error-prone repair as well as in pneumococcus and Enterococcus
faecalis UV202. Mutations within ORF13 abolished UV-induced
mutagenesis but did not affect the conjugal transposition of the element.
0021-9193/99/$04.00+0
Copyright © 1999, American Society for Microbiology. All rights reserved.
An Operon That Confers UV Resistance by Evoking the
SOS Mutagenic Response in Streptococcal Conjugative Transposon
Tn5252
*
Corresponding author. Mailing address: 315 LSE,
Department of Microbiology and Molecular Genetics, Oklahoma State
University, Stillwater, OK 74078. Phone: (405) 744-7730. Fax: (405)
744-6790. E-mail: nirmal{at}okstate.edu.
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