title: An investigation into the ability of C-terminal homologues of Escherichia coli low molecular mass penicillin-binding proteins 4, 5 and 6 to undergo membrane interaction.
abstract: The Escherichia coli low molecular mass penicillin-binding proteins (PBP4, PBP5 and PBP6) are a group of penicillin-sensitive enzymes involved in the final stages of cell wall assembly. It has been suggested that these proteins may interact with the periplasmic face of the inner membrane via C-terminal amphiphilic alpha-helices. Theoretical analysis has predicted that these C-terminal helical regions may be membrane interactive. We have tested this hypothesis by assaying PBP C-terminal homologues (P4, P5 and P6) for haemolytic activity. Our results show that the PBP5 and PBP6 C-terminal homologues readily lyse sheep erythrocytes in a pH-dependent manner with LD50's of 3.5 x 10(-6) M and 6.8 x 10(-7) M respectively at pH 7. These results appear to support the present model for the membrane anchoring of PBP5 and PBP6. The PBP4 C-terminal homologue shows no evidence of haemolytic activity which could imply a different means of membrane association for PBP4.
authors.affiliation: Department of Applied Biology, University of Central Lancashire, Preston, United Kingdom.
authors.forename: F
authors.initials: F
authors.lastname: Harris
authors.forename: D A
authors.initials: DA
authors.lastname: Phoenix
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001426:Bacterial Proteins / Q000737:chemistry / Q000378:metabolism*; D002352:Carrier Proteins / Q000737:chemistry / Q000378:metabolism*; D004910:Erythrocyte Membrane / Q000378:metabolism*; D004926:Escherichia coli / Q000201:enzymology*; D006461:Hemolysis / Q000187:drug effects; D006602:Hexosyltransferases; D006863:Hydrogen-Ion Concentration; D008555:Melitten / Q000494:pharmacology; D008969:Molecular Sequence Data; D002267:Muramoylpentapeptide Carboxypeptidase / Q000737:chemistry / Q000378:metabolism*; D046915:Penicillin-Binding Proteins; D010455:Peptides / Q000737:chemistry / Q000378:metabolism*; D010458:Peptidyl Transferases; D017433:Protein Structure, Secondary; D012756:Sheep
chemical_list: D001426:Bacterial Proteins; D002352:Carrier Proteins; D046915:Penicillin-Binding Proteins; D010455:Peptides; D008555:Melitten; D010458:Peptidyl Transferases; D006602:Hexosyltransferases; D002267:Muramoylpentapeptide Carboxypeptidase