Nucleotide sequence and molecular characterization of a gene encoding GTP-binding protein from Streptococcus gordonii

A 1286-bp fragment of chromosomal DNA from Streptococcus gordonii strain Challis was cloned and sequenced. The gene sgg consisted of 897-bp nucleotides encoding a 299-amino acid polypeptide (33 200 Dal. The deduced amino acid sequence exhibited significant similarity to Era, G protein of Escherichia coli. The nucleotide binding assay demonstrated that recombinant Sgg bound [P-32]GTP but not [P-32]ATP, [P-32]CTP, or [P-32]UTP. These findings indicate that Sgg is a member of the G protein superfamily in the genus Streptococcus.