Surface location of HPr, a phosphocarrier of the phosphoenolpyruvate: sugar phosphotransferase system in Streptococcus suis.
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 I 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.
Dubreuil
J D
JD
Department of Pathology and Microbiology, Faculty of Veterinary Medicine, Université de Montréal, PO Box 5000, Saint Hyacinthe, Québec J2S 7C6, Canada.
Jacques
M
M
Department of Pathology and Microbiology, Faculty of Veterinary Medicine, Université de Montréal, PO Box 5000, Saint Hyacinthe, Québec J2S 7C6, Canada.
Brochu
D
D
Groupe de Recherche en Ecologie Buccale (GREB), Department of Biochemistry (Sciences) and Faculty of Dentistry, Université Laval, Québec G1K 7P4, Canada.
Frenette
M
M
Groupe de Recherche en Ecologie Buccale (GREB), Department of Biochemistry (Sciences) and Faculty of Dentistry, Université Laval, Québec G1K 7P4, Canada.
Vadeboncoeur
C
C
Groupe de Recherche en Ecologie Buccale (GREB), Department of Biochemistry (Sciences) and Faculty of Dentistry, Université Laval, Québec G1K 7P4, Canada.
D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism / Q000648:ultrastructure; D016253:Microscopy, Immunoelectron; D008969:Molecular Sequence Data; D008970:Molecular Weight; D010731:Phosphoenolpyruvate Sugar Phosphotransferase System / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D017386:Sequence Homology, Amino Acid; D013045:Species Specificity; D013291:Streptococcus / Q000235:genetics; D017011:Streptococcus suis / Q000235:genetics / Q000378:metabolism* / Q000648:ultrastructure
D001426:Bacterial Proteins; D010731:Phosphoenolpyruvate Sugar Phosphotransferase System; C030182:phosphocarrier protein HPr