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The protein encoded by gvpC is a minor component of gas vesicles isolated from the cyanobacteria Anabaena flos‐aquae and Microcyctis sp.
Author(s) -
Hayes P. K.,
Lazarus C. M.,
Bees A.,
Walker J. E.,
Walsby A. E.
Publication year - 1988
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1111/j.1365-2958.1988.tb00062.x
Subject(s) - biology , anabaena , amino acid , vesicle , biochemistry , homology (biology) , peptide sequence , cyanobacteria , microbiology and biotechnology , gene , bacteria , genetics , membrane
Summary The proteins present in gas vesicles of the cyanobacteria Anabaena flos‐aquae and Microcystis sp. Were separated by SDS‐polyacrylamide gel electrophoresis. Each contained a protein of M r 22 K whose N‐terminal amino acid sequences showed homology with that of the Calothrix sp. PCC 7601 gvpC gene product. The gvpC gene from A. flos‐aquae was cloned and sequenced. The derived amino acid sequence for the gene product indicated a protein, GVPc, of 193 residues and M r 21985 containing five highly conserved 33 amino acid repeats. The sequence was identical at the N‐terminus to that of the M r 22K protein present in gas vesicles and showed correspondence to seven tryptic peptides isolated from gas vesicles. This establishes that GVPc forms a second protein component of the gas vesicle, in addition to the main constituent, the 70 residue GVPa. Quantitative amino acid analysis of entire gas vesicles reveals that GVPc accounts for only 2.9% of the protein molecules and 8.2% of the mass present: this is insufficient to form the conical end caps of the gas vesicles. It is suggested that GVPc provides the hydrophilic outer surface of the gas vesicle wall; the 33 amino acid repeats may interact with the periodic structure provided by GVPa.