Aspergillus nidulans Protein O-Mannosyltransferases Play Roles in Cell Wall Integrity and Developmental Patterning

作者：Kriangkripipat Thanyanuch; Momany Michelle^*

来源：Eukaryotic Cell, 2009, 8(10): 1475-1485.

DOI：10.1128/EC.00040-09

Protein O-mannosyltransferases (Pmts) initiate O-mannosyl glycan biosynthesis from Ser and Thr residues of target proteins. Fungal Pmts are divided into three subfamilies, Pmt1, -2, and -4. Aspergillus nidulans possesses a single representative of each Pmt subfamily, pmtA (subfamily 2), pmtB (subfamily 1), and pmtC (subfamily 4). In this work, we show that single Delta pmt mutants are viable and have unique phenotypes and that the Delta pmtA Delta pmtB double mutant is the only viable double mutant. This makes A. nidulans the first fungus in which all members of individual Pmt subfamilies can be deleted without loss of viability. At elevated temperatures, all A. nidulans Delta pmt mutants show cell wall-associated defects and increased sensitivity to cell wall-perturbing agents. The Delta pmt mutants also show defects in developmental patterning. Germ tube emergence is early in Delta pmtA and more frequent in Delta pmtC mutants than in the wild type. In Delta pmtB mutants, intrahyphal hyphae develop. All Delta pmt mutants show distinct conidiophore defects. The Delta pmtA strain has swollen vesicles and conidiogenous cells, the Delta pmtB strain has swollen conidiophore stalks, and the Delta pmtC strain has dramatically elongated conidiophore stalks. We also show that AN5660, an ortholog of Saccharomyces cerevisiae Wsc1p, is modified by PmtA and PmtC. The Delta pmt phenotypes at elevated temperatures, increased sensitivity to cell wall-perturbing agents and restoration to wild-type growth with osmoticum suggest that A. nidulans Pmts modify proteins in the cell wall integrity pathway. The altered developmental patterns in Delta pmt mutants suggest that A. nidulans Pmts modify proteins that serve as spatial cues.

• 出版日期2009-10