RT Journal Article SR Electronic(1) A1 Lortie, Louis-André A1 Pelletier, Michel A1 Vadeboncoeur, Christian A1 Frenette, Michel YR 2000 T1 The gene encoding IIABLMan in Streptococcus salivarius is part of a tetracistronic operon encoding a phosphoenolpyruvate:mannose/glucose phosphotransferase systemThe GenBank accession number for the sequence reported in this paper is AF130465. JF Microbiology, VO 146 IS 3 SP 677 OP 685 DO https://doi.org/10.1099/00221287-146-3-677 PB Microbiology Society, SN 1465-2080, AB Glucose and mannose are transported in streptococci by the mannose-PTS (phosphoenolpyruvate:mannose phosphotransferase system), which consists of a cytoplasmic IIAB protein, called IIABMan, and an uncharacterized membrane permease. This paper reports the characterization of the man operon encoding the specific components of the mannose-PTS of Streptococcus salivarius. The man operon was composed of four genes, manL, manM, manN and manO. These genes were transcribed from a canonical promoter (Pman) into a 3·6 kb polycistronic mRNA that contained a 5′-UTR (untranslated region). The predicted manL gene product encoded a 35·5 kDa protein and contained the amino acid sequences of the IIA and IIB phosphorylation sites already determined from purified S. salivarius . Expression of manL in Escherichia coli generated a 35 kDa protein that reacted with antibodies. The predicted ManM protein had an estimated size of 27·2 kDa. ManM had similarity with IIC domains of the mannose-EII family, but did not possess the signature proposed for mannose-IIC proteins from Gram-negative bacteria. From multiple alignment analyses of sequences available in current databases, the following modified IICMan signature is proposed: GX3G[DNH]X3G[LIVM]2XG2[STL][LT][EQ]. The deduced product of manN was a hydrophobic protein with a predicted molecular mass of 33·4 kDa. The ManN protein contained an amino acid sequence similar to the signature sequence of the IID domains of the mannose-EII family. manO encoded a 13·7 kDa protein. This gene was also transcribed as a monocistronic mRNA from a promoter located in the manN–manO intergenic region. A search of current databases revealed the presence of , ManM, ManN and ManO orthologues in Streptococcus mutans, Streptococcus pyogenes, Streptococcus pneumoniae and Enterococcus faecalis. This work has elucidated the molecular structure of the mannose PTS in streptococci and enterococci, and demonstrated the presence of a putative regulatory protein (ManO) within the man operon., UL https://www.microbiologyresearch.org/content/journal/micro/10.1099/00221287-146-3-677