%0 Journal Article %A Dubreuil, J. D. %A Jacques, M. %A Brochu, D. %A Frenette, M. %A Vadeboncoeur, C. %T Surface location of HPr, a phosphocarrier of the phosphoenolpyruvate: sugar phosphotransferase system in Streptococcus suis %D 1996 %J Microbiology, %V 142 %N 4 %P 837-843 %@ 1465-2080 %R https://doi.org/10.1099/00221287-142-4-837 %K phospotransferase system %K methionine aminopeptidase %K cell surface proteins %K Streptococcus suis. %K HPr %I Microbiology Society, %X HPr is a low-molecular-mass phosphocarrier protein of the bacterial phosphoenolpyruvate (PEP): sugar phosphotransferase system (PTS) found in the cytoplasm or associated with the inner surface of the cytoplasmic membrane. Treatment of Streptococcus suis cells with a Sorvall Omnimixer, a technique used to extract cell surface components, resulted in the extraction of a major protein with a molecular mass of 9 kDa. Several lines of evidence suggested that this protein was HPr: (i) the S. suis protein showed homology over the first 35 N-terminal amino acid residues with the HPrs of Streptococcus salivarius and Streptococcus mutans, including the signature sequence for the site of PEP-dependent phosphorylation; (ii) it cross-reacted with the S. salivarius anti-HPr antibody preparation; (iii) it could be phosphorylated by enzyme 1 at the expense of PEP, and by a membrane-associated kinase at the expense of ATP; and (iv) it possessed phosphocarrier activity when used as a source of HPr in an in vitro PTS assay. The data suggested that a portion of the cellular HPr is associated with the external cell surface in S. suis, a result that was confirmed by immunogold electron microscopy. The cellular HPr of S. suis consisted of two forms that could be distinguished by the presence or the absence of the N-terminal methionine. Amino acid sequence analysis indicated that the cell-surface-associated HPr of S. suis lacked the N-terminal methionine residue. %U https://www.microbiologyresearch.org/content/journal/micro/10.1099/00221287-142-4-837