Aspergillus fumigatus Mnn9 is responsible for mannan synthesis and required for covalent linkage of mannoprotein to the cell wall.

ABSTRACT: Owing to the essential role in protection of the Aspergillus fumigatus cell against human defense reactions, its cell wall has long been taken as a promising antifungal target. The cell wall of A. fumigatus composed of chitin, glucan and galactomannan and mannoproteins. Although galactomannan has been used as a diagnostic target for a long time, its biosynthesis remains unknown in A. fumigatus. In this study, a putative ?1,6-mannosyltransferase gene mnn9 was identified in A. fumigatus. Deletion of the mnn9 gene resulted in an increased sensitivity to calcofluor white, Congo red, or hygromycin B as well as in reduced cell wall components and abnormal polarity. Although there was no major effect on N-glycan synthesis, covalently-linked cell wall mannoprotein Mp1 was significantly reduced in the mutant. Based on our results, we propose that Mnn9p is a mannosyltransferase responsible for the formation of the ?-mannan in cell wall mannoproteins, potentially via elongation of O-linked mannose chains.

SUBMITTER: Du T 

PROVIDER: S-EPMC6858276 | biostudies-literature | 2019 Jul

REPOSITORIES: biostudies-literature