title: Analysis of tryptic digests indicates regions of GvpC that bind to gas vesicles of Anabaena flos-aquae.
abstract: The gas vesicles of the cyanobacterium Anabaena flos-aquae contain two main proteins: GvpA, which forms the ribs of the hollow cylindrical shell, and GvpC, which occurs on the outer surface. Analysis by MALDI-TOF MS shows that after incubating Anabaena gas vesicles in trypsin, GvpA was cleaved only at sites near the N-terminus, whereas GvpC was cleaved at most of its potential tryptic sites. Many of the resulting tryptic peptides from GvpC remained attached to the underlying GvpA shell: the pattern of attachment indicated that there are binding sites to GvpA at both ends of the 33-residue repeats (33RRs) in GvpC, although one of the tryptic peptides within the 33RR did not remain attached. Tryptic peptides near the two ends of the GvpC molecule were also lost. The mean critical collapse pressure of Anabaena gas vesicles decreased from 0.63 MPa to 0.20 MPa when GvpC was removed with urea or fully digested with trypsin; partial digestion resulted in partial decrease in critical pressure.
authors.affiliation: School of Biological Sciences, University of Bristol, Bristol BS8 1UG, UK.
authors.forename: Peter G
authors.initials: PG
authors.lastname: Dunton
authors.affiliation: Department of Biochemistry, University of Bristol, Bristol BS8 1UG, UK.
authors.forename: William J
authors.initials: WJ
authors.lastname: Mawby
authors.affiliation: Department of Biochemistry, University of Bristol, Bristol BS8 1UG, UK.
authors.forename: Virginia A
authors.initials: VA
authors.lastname: Shaw
authors.affiliation: School of Biological Sciences, University of Bristol, Bristol BS8 1UG, UK.
authors.forename: Anthony E
authors.initials: AE
authors.lastname: Walsby
mesh_terms: D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D001665:Binding Sites; D046869:Dolichospermum flos-aquae / Q000235:genetics / Q000378:metabolism* / Q000648:ultrastructure; D005740:Gases; D008565:Membrane Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D010455:Peptides / Q000737:chemistry / Q000378:metabolism; D011506:Proteins / Q000737:chemistry / Q000378:metabolism; D014357:Trypsin / Q000378:metabolism*; D014617:Vacuoles / Q000737:chemistry / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; D005740:Gases; C076193:GvpC protein, Anabaena flos-aquae; D008565:Membrane Proteins; D010455:Peptides; D011506:Proteins; C038524:gas vesicle protein; D014357:Trypsin