title: Carbohydrate-reactive, pore-forming outer membrane proteins of Aeromonas hydrophila.
abstract: Two outer membrane proteins of Aeromonas hydrophila A6, isolated in a one-step affinity chromatography process based on carbohydrate reactivity, were found to be pore-forming molecules in artificial planar bilayer membranes. These carbohydrate-reactive outer membrane proteins (CROMPs; M(r)s, 40,000 and 43,000) were subjected to amino acid analysis. The amino acid profiles for these two outer membrane proteins were almost identical. A partial protein sequence of a 14-amino-acid fragment of the 40,000-Da protein revealed homology with outer membrane porins of Escherichia coli and A. hydrophila. CROMPs were compared with carbohydrate-reactive porins also extracted from outer membranes of A. hydrophila A6. These porins were isolated by using standard porin purification techniques (insolubility in 2% sodium dodecyl sulfate, solubility in 0.4 M NaCl, and Sephacryl S-200 gel filtration), and then Synsorb H type 2 affinity chromatography was done. The physical and functional properties of the carbohydrate-reactive porins and CROMPs were found to be identical. On the basis of pore-forming properties in planar lipid bilayers and channel inhibition with maltotriose solutions, a nonspecific, general diffusion porin and a LamB-like maltoporin were identified in both CROMP and carbohydrate-reactive porin preparations. To our knowledge, the use of carbohydrate reactivity to isolate channel-forming proteins from bacterial outer membranes has not been reported previously.
authors.affiliation: Centre for Advanced Biomedical Studies, School of Pharmacy and Medical Sciences, University of South Australia.
authors.forename: D M
authors.initials: DM
authors.lastname: Quinn
authors.forename: H M
authors.initials: HM
authors.lastname: Atkinson
authors.forename: A H
authors.initials: AH
authors.lastname: Bretag
authors.forename: M
authors.initials: M
authors.lastname: Tester
authors.forename: T J
authors.initials: TJ
authors.lastname: Trust
authors.forename: C Y
authors.initials: CY
authors.lastname: Wong
authors.forename: R L
authors.initials: RL
authors.lastname: Flower
mesh_terms: D016980:Aeromonas hydrophila / Q000737:chemistry* / Q000472:pathogenicity; D001425:Bacterial Outer Membrane Proteins; D002240:Carbohydrate Sequence; D002241:Carbohydrates / Q000494:pharmacology*; D007473:Ion Channels / Q000187:drug effects; D008969:Molecular Sequence Data; D018272:Porins / Q000032:analysis*; D011991:Receptors, Virus / Q000032:analysis; D014774:Virulence; D014871:Water Microbiology
chemical_list: D001425:Bacterial Outer Membrane Proteins; D002241:Carbohydrates; D007473:Ion Channels; D018272:Porins; D011991:Receptors, Virus; C016532:maltoporins