Linkages between macromolecules in Candida albicans cell wall.

Wall mannoproteins can be divided into two major groups depending upon their degree of interaction with the structural network: one type interacts by non-covalent bonds while the second group seems covalently bound to other wall components (intrinsic or structural mannoproteins). Cytological and biochemical studies have shown that mannoproteins are distributed randomly throughout cell wall interacting with glucan, chitin and other mannoproteins. Experimental results obtained using regenerating protoplasts have shown that building of the wall occurs in two steps: during the first one the skeleton of chitin is formed retaining protein molecules by non-covalent bonds. The second steps take place by deposition of glucan molecules that allows incorporation of mannoproteins probably by covalent linkages. Using two monoclonal antibodies, one of them reacting with a mycelial specific antigen and a second one with an epitope found in yeast and mycelial cells, two families of proteins are detected, that are secreted independently. The antigens reacting with both monoclonal antibodies are solubilized from the walls of each morphologic structure forming part of supramolecular structures.

Evidence for the formation of covalent bonds between macromolecules in the domain of the wall of Candida albicans mycelial cells.

An O-glycosylated mannoprotein, after its incorporation into the wall, showed an increase in its molecular weight, due at least to its association with N-glycosidic sugar chain(s). This was shown by rendering the material soluble after partial degradation of the wall structure. At present it is unknown whether this phenomenon is due to an additional transglycosylation process or whether the partial degradation of the wall solubilizes a supramolecular structure formed between the original O-glycosylated protein which becomes linked either directly or indirectly through a protein to the N-sugar chain(s).