title: Penicillin-binding protein 5 can form a homo-oligomeric complex in the inner membrane of Escherichia coli.
abstract: Penicillin-binding protein 5 (PBP5) is a DD-carboxypeptidase, which cleaves the terminal D-alanine from the muramyl pentapeptide in the peptidoglycan layer of Escherichia coli and other bacteria. In doing so, it varies the substrates for transpeptidation and plays a key role in maintaining cell shape. In this study, we have analyzed the oligomeric state of PBP5 in detergent and in its native environment, the inner membrane. Both approaches indicate that PBP5 exists as a homo-oligomeric complex, most likely as a homo-dimer. As the crystal structure of the soluble domain of PBP5 (i.e., lacking the membrane anchor) shows a monomer, we used our experimental data to generate a model of the homo-dimer. This model extends our understanding of PBP5 function as it suggests how PBP5 can interact with the peptidoglycan layer. It suggests that the stem domains interact and the catalytic domains have freedom to move from the position observed in the crystal structure. This would allow the catalytic domain to have access to pentapeptides at different distances from the membrane.
authors.affiliation: Centre for Biomembrane Research, Department of Biochemistry and Biophysics, Stockholm University, Stockholm SE-106 91, Sweden.
authors.forename: Karl
authors.initials: K
authors.lastname: Skoog
authors.forename: Filippa Stenberg
authors.initials: FS
authors.lastname: Bruzell
authors.forename: Aurélie
authors.initials: A
authors.lastname: Ducroux
authors.forename: Mårten
authors.initials: M
authors.lastname: Hellberg
authors.forename: Henrik
authors.initials: H
authors.lastname: Johansson
authors.forename: Janne
authors.initials: J
authors.lastname: Lehtiö
authors.forename: Martin
authors.initials: M
authors.lastname: Högbom
authors.forename: Daniel O
authors.initials: DO
authors.lastname: Daley
mesh_terms: D002462:Cell Membrane / Q000378:metabolism*; D004591:Electrophoresis, Polyacrylamide Gel; D004926:Escherichia coli / Q000378:metabolism*; D029968:Escherichia coli Proteins / Q000737:chemistry* / Q000378:metabolism*; D008565:Membrane Proteins / Q000737:chemistry* / Q000378:metabolism*; D046915:Penicillin-Binding Proteins / Q000737:chemistry* / Q000378:metabolism*; D010457:Peptidoglycan / Q000737:chemistry / Q000378:metabolism; D011485:Protein Binding; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary
chemical_list: D029968:Escherichia coli Proteins; D008565:Membrane Proteins; D046915:Penicillin-Binding Proteins; D010457:Peptidoglycan