Identification of another surface protein antigen I/II gene, paaB, and a putative transcriptional regulator gene, par, from Streptococcus cricetus.
The flanking region of the antigen I/II gene, paaA, in Streptococcus cricetus was examined using the gene-walking technique. In the region downstream of the paaA gene, another antigen I/II gene designated as paaB was found. The paaB gene was disrupted at the alanine-rich region (A region) by a novel insertion sequence element, ISScr1. ISScr1 is a member of the IS982 family and is composed of a 962-bp sequence and duplicated target DNA (the sequence 5'-TAGCTAAAT-3') resulting from its insertion. To clarify the structural divergence of the two antigen I/II proteins (PAaA and PAaB), computational analysis of the paaB gene was performed and the two structures were compared. The amino acid sequence homology indicated that PAaB resembled PAaA, but the middle region showed little similarity to that of PAaA. Phylogenetic analysis showed that PAaB was better classified in a major group with S. mutans PAc and S. gordonii SspA and SspB than with PAaA. The transcriptional expression of paaA and paaB was demonstrated by reverse transcription (RT)-PCR. In the region upstream of the paaA gene, three genes homologous to the genes located in the region upstream of the S. sobrinus antigen I/II gene (pag) were found. Of the three genes, ORF3 showed homology to the par gene encoding a transcriptional repressor for the pag gene in S. sobrinus. Therefore, ORF3 was designated the par gene of S. cricetus. Southern hybridization revealed that the par gene of S. cricetus was not found in other oral streptococci examined in this study.
Department of Dental Pharmacology, School of Dentistry, Iwate Medical University, Morioka, Japan.
Haruki
H
Tamura
Arisa
A
Yamada
Hiroko
H
Saito
Shigeo
S
Murai
Hirohisa
H
Kato
D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism; D003001:Cloning, Molecular; D004251:DNA Transposable Elements; D021901:DNA, Intergenic; D015964:Gene Expression Regulation, Bacterial; D005809:Genes, Regulator; D008562:Membrane Glycoproteins / Q000235:genetics* / Q000378:metabolism; D008969:Molecular Sequence Data; D016366:Open Reading Frames; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017386:Sequence Homology, Amino Acid; D013291:Streptococcus / Q000235:genetics* / Q000378:metabolism; D014158:Transcription, Genetic
D001426:Bacterial Proteins; D004251:DNA Transposable Elements; D021901:DNA, Intergenic; D008562:Membrane Glycoproteins; C055764:S-layer proteins