title: Initial characterization of the Streptococcus gordonii htpX gene.
abstract: Examination of the Streptococcus gordonii chromosomal region, which lies immediately upstream of the glucosyltransferase positive regulatory determinant rgg, revealed two open reading frames. Based on nucleotide sequences, these genes were similar to the Listeria monocytogenes lemA gene, which is involved in antigen presentation, and the Escherichia coli htpX heat shock gene, which has an unknown function. Northern hybridization analysis indicated that S. gordonii lemA and htpX genes were associated with a ca. 1.7-kb polycistronic transcript. Although levels of the lemA/htpX transcript did not increase in response to heat to levels seen with dnaK controls, insertional inactivation of htpX resulted in changes in adhesiveness, cellular morphology and detergent-extractable surface antigens in cells grown at 41 degrees C, implying that htpX may be involved in surface protein expression. Insertional inactivation of lemA and htpX indicated that, despite their proximity to rgg and the structural gene, gtfG, these upstream genes do not affect S. gordonii glucosyltransferase activity.
authors.affiliation: Department of Oral Surgery and Hospital Dentistry, School of Dentistry, Indiana University, 1121 West Michigan Street, Indianapolis, IN 46202, USA.
authors.forename: M M
authors.initials: MM
authors.lastname: Vickerman
authors.forename: N M
authors.initials: NM
authors.lastname: Mather
authors.forename: P E
authors.initials: PE
authors.lastname: Minick
authors.forename: C A
authors.initials: CA
authors.lastname: Edwards
mesh_terms: D000595:Amino Acid Sequence; D000942:Antigens, Bacterial; D001422:Bacterial Adhesion / Q000235:genetics*; D001426:Bacterial Proteins / Q000235:genetics / Q000502:physiology; D001483:Base Sequence; D002462:Cell Membrane; D004269:DNA, Bacterial / Q000032:analysis; D029968:Escherichia coli Proteins; D005798:Genes, Bacterial; D006360:Heat-Shock Proteins / Q000235:genetics* / Q000502:physiology; D045726:Metalloproteases; D008969:Molecular Sequence Data; D016254:Mutagenesis, Insertional; D015183:Restriction Mapping; D017422:Sequence Analysis, DNA; D013298:Streptococcus sanguis / Q000235:genetics*; D014157:Transcription Factors / Q000235:genetics / Q000502:physiology
chemical_list: D000942:Antigens, Bacterial; D001426:Bacterial Proteins; D004269:DNA, Bacterial; D029968:Escherichia coli Proteins; D006360:Heat-Shock Proteins; D014157:Transcription Factors; C068607:HtpX protein, E coli; C074165:lemA protein, bacterial; D045726:Metalloproteases