Polypeptide pattern of the insoluble wall component of Chlamydomonas reinhardii and its variation during the vegetative cell cycle

Abstract

The cell wall of the unicellular green alga Chlamydomonas reinhardii consists of several salt-soluble glycoproteins and a framework of insoluble glycoproteins (K. Roberts, Phil. Trans. R. Soc. London B268 (1974) 129–146). This insoluble framework of the Chlamydomonas cell wall was completely solubilized by chemical deglycosylation with either trifluoromethanesulfonic acid or hydrogen fluoride in pyridine. Mild treatments with alkali or acid, however, did not destroy the insoluble wall component. Our findings suggest that the polypeptide subunits of the insoluble glycoprotein framework may be cross-linked through carbohydrate side chains. We demonstrate here that the pattern of polypeptides released from the insoluble wall component during chemical deglycosylation varies in a cell-cycle dependent manner. The insoluble wall component of all the analyzed cell cycle stages contained relatively constant amounts of polypeptides subunits with apparent molecular weights of >300, 150 and 64 kDa. Polypeptides with apparent molecular weights of 47 kDa and 22 kDa accumulated during cell growth, but were not present in the insoluble wall component of released zoospores. After apparent cytokinesis, increasing amounts of a 60-kDa and a 43-kDa polypeptide were detected. These polypeptides disappeared during liberation of zoospores.