title: Investigations into the mechanisms used by the C-terminal anchors of Escherichia coli penicillin-binding proteins 4, 5, 6 and 6b for membrane interaction.
abstract: Escherichia coli low molecular mass penicillin-binding proteins (PBPs) include PBP4, PBP5, PBP6 and PBP6b. Evidence suggests that these proteins interact with the inner membrane via C-terminal amphiphilic alpha-helices. Nonetheless, the membrane interactive mechanisms utilized by the C-terminal anchors of PBP4 and PBP6b show differences to those utilized by PBP5 and PBP6. Here, hydrophobic moment-based analyses have predicted that, in contrast to the PBP4 and PBP6b C-termini, those of PBP5 and PBP6 are candidates to form oblique orientated alpha-helices. Consistent with these predictions, Fourier transform infrared spectroscopy (FTIR) has shown that peptide homologs of the PBP4 and PBP5 C-terminal regions, P4 and P5, respectively, both possessed the ability to adopt alpha-helical structure in the presence of lipid. However, whereas P4 appeared to show a preference for interaction with the surface regions of dimyristoylglycerophosphoethanolamine and dimyristoylglycerophosphoglycerol membranes, P5 appeared to show deep penetration of both these latter membranes and dimyristoylglycerophosphocholine membranes. Based on these results, we have suggested that in contrast to the membrane anchoring of the PBP4 and PBP6b C-terminal alpha-helices, the PBP5 and PBP6 C-terminal alpha-helices may possess hydrophobicity gradients and penetrate membranes in an oblique orientation.
authors.affiliation: Department of Forensic and Investigative Science, University of Central Lancashire, Preston, UK.
authors.forename: Frederick
authors.initials: F
authors.lastname: Harris
authors.forename: Klaus
authors.initials: K
authors.lastname: Brandenburg
authors.forename: Ulrich
authors.initials: U
authors.lastname: Seydel
authors.forename: David
authors.initials: D
authors.lastname: Phoenix
mesh_terms: D000595:Amino Acid Sequence; D001426:Bacterial Proteins; D002352:Carrier Proteins / Q000737:chemistry / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism; D004926:Escherichia coli / Q000378:metabolism*; D006602:Hexosyltransferases; D008969:Molecular Sequence Data; D002267:Muramoylpentapeptide Carboxypeptidase / Q000737:chemistry / Q000378:metabolism*; D046915:Penicillin-Binding Proteins; D010458:Peptidyl Transferases; D010743:Phospholipids / Q000737:chemistry; D011487:Protein Conformation; D017550:Spectroscopy, Fourier Transform Infrared; D013696:Temperature
chemical_list: D001426:Bacterial Proteins; D002352:Carrier Proteins; D046915:Penicillin-Binding Proteins; D010743:Phospholipids; D010458:Peptidyl Transferases; D006602:Hexosyltransferases; D002267:Muramoylpentapeptide Carboxypeptidase