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 Da). The deduced amino acid sequence exhibited significant similarity to Era, G protein of Escherichia coli. The nucleotide binding assay demonstrated that recombinant Sgg bound [32P]GTP but not [32P]ATP, [32P]CTP, or [32P]UTP. These findings indicate that Sgg is a member of the G protein superfamily in the genus Streptococcus.