Isolation and structural proteins determination of gas vesicles from a bloom-forming cyanobacterium

Abstract:

[Objective] In order to isolate high-purity and intact gas vesicles from the cells of bloom-forming cyanobacterium Microcystis aeruginosa PCC 7806, and to identify structural proteins of gas vesicles. [Methods] Osmotic shock combined with lysozyme treatment and low speed centrifugation were used to isolate and purify gas vesicles. The purity, integrity and characteristic shape of gas vesicles were examined by negative staining and transmission electron microscope. The structural proteins of gas vesicles were detected and identified by SDS-PAGE electrophoresis and LC-MS. [Results] Electron microscopic examination indicated that the isolated gas vesicles had high purity and showed good integrity. They took a cylinder shape with conical end caps and had a similar diameter of about 120 nm and the variable lengths from 500 to 1 500 nm. GvpA and GvpC identified by SDS-PAGE electrophoresis and LC-MS were two main structural proteins of gas vesicles. [Conclusion] Our findings would have great significance to reveal the fine structure of gas vesicles and to further study the buoyancy regulation mechanism of bloom-forming cyanobacteria.