Glucanosyltransglycosylase Activity of the Glucan-Remodeling Enzyme Bgl2p in the Yeast Cell Wall: Detection and Characterization

In isolated Saccharomyces cerevisiae cell walls (CWs) obtained without using denaturing agents, Bgl2p demonstrates hydrolysis of the laminaripentaose forming a disaccharide and generates the glucanosyltransglycosylase activity product, laminarioctaose, that confirms the results obtained previously for the enzyme isolated using denaturing conditions. Activity is detected in the CWs of the parental yeast strain and is not detected in the CWs of a strain with a deletion of BGL2 gene, that lacks Bgl2p. For the first time, Bgl2p activity was investigated under conditions as similar as possible to in vivo; the absence of the influence of high-molecular-weight polyphosphates, universal regulators of protein functioning, and resistance to the hydrolysis of trypsin together allow us to put forward a hypothesis about the significant protection of the Bgl2p molecule by the CW components.