Nucleotide sequence of the hexA gene for DNA mismatch repair in Streptococcus pneumoniae and homology of hexA to mutS of Escherichia coli and Salmonella typhimurium

Journal Article · Fri Jan 01 04:00:00 EST 1988 · J. Bacteriol.; (United States)

OSTI ID:5317604

Priebe, S D; Hadi, S M; Greenberg, B; Lacks, S A

The Hex system of heteroduplex DNA base mismatch repair operates in Streptococcus pneumoniae after transformation and replication to correct donor and nascent DNA strands, respectively. A functionally similar system, called Mut, operates in Escherichia coli and Salmonella typhimurium. The nucleotide sequence of a 3.8-kilobase segment from the S. pneumoniae chromosome that includes the 2.7-kilobase hexA gene was determined. Chromosomal DNA used as donor to measure Hex phenotype was irradiated with UV light. An open reading frame that could encode a 17-kilodalton polypeptide (OrfC) was located just upstream of the gene encoding a polypeptide of 95 kilodaltons corresponding to HexA. Shine-Dalgarno sequences and putative promoters were identified upstream of each protein start site. Insertion mutations showed that only HexA functioned in mismatch repair and that the promoter for hexA transcription was located within the OrfC-coding region. The HexA polypeptide contains a consensus sequence for ATP- or GTP-binding sites in proteins. Comparison of the entire HexA protein sequence to that of MutS of S. typhimurium, showed the proteins to be homologous, inasmuch as 36% of their amino acid residues were identical. This homology indicates that the Hex and Mut systems of mismatch repair evolved from an ancestor common to the gram-positive streptococci and the gram-negative enterobacteria. It is the first direct evidence linking the two systems.

• Research Organization: Brookhaven National Lab., Upton, NY (USA)
• OSTI ID: 5317604
• Journal Information: J. Bacteriol.; (United States), Journal Name: J. Bacteriol.; (United States) Vol. 170:1; ISSN JOBAA
• Country of Publication: United States
• Language: English

Related Subjects

550200* -- Biochemistry
560130 -- Radiation Effects on Microorganisms
59 BASIC BIOLOGICAL SCIENCES
63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
BACTERIA
BIOLOGICAL RECOVERY
BIOLOGICAL REPAIR
DNA MISMATCH
DNA REPAIR
DNA SEQUENCING
ELECTROMAGNETIC RADIATION
ESCHERICHIA COLI
GENE REPRESSORS
MICROORGANISMS
NUCLEOPROTEINS
ORGANIC COMPOUNDS
PROTEINS
RADIATIONS
RECOVERY
REPAIR
SALMONELLA
SALMONELLA TYPHIMURIUM
STREPTOCOCCUS
STRUCTURAL CHEMICAL ANALYSIS
TRANSCRIPTION
ULTRAVIOLET RADIATION