Molecular weight of gas-vesicle protein from the planktonic cyanobacterium Anabaena flos-aquae and implications for structure of the vesicle

Abstract

The gas vesicle of the planktonic cyanobacterium A. flos-aquae is a cylindrical shell made of protein enclosing a gas-filled space. Protein sequence analysis shows that the vesicle is made from a single protein. By gel electrophoresis and amino acid analysis, its MW was estimated as 20,600. Taken with previously obtained X-ray data, a simple interpretation of its molecular structure is of the polypeptide snaking in 6 pairs of antiparallel chains, 3 in each layer. The molecule would repeat along the ribs of the vesicle at intervals of 3.4 nm.