Eukaryotic Cell, October 2009, p. 1465-1474, Vol. 8, No. 10
1535-9778/09/$08.00+0 doi:10.1128/EC.00371-08
Copyright © 2009, American Society for Microbiology. All Rights Reserved.
Protein O-Mannosyltransferases B and C Support Hyphal Development and Differentiation in Aspergillus nidulans
,
Masatoshi Goto,1*
Yuka Harada,1
Takuji Oka,1,
Sho Matsumoto,1
Kaoru Takegawa,1 and
Kensuke Furukawa2
Department of Bioscience and Biotechnology, Faculty of Agriculture, Kyushu University, Fukuoka 812-8581,1 Department of Food and Bioscience, Faculty of Food Science and Nutrition, Beppu University, Beppu 874-8501, Japan2
Received 19 November 2008/ Accepted 27 July 2009
Aspergillus nidulans possesses three pmt genes encoding protein O-D-mannosyltransferases (Pmt). Previously, we reported that PmtA, a member of the PMT2 subfamily, is involved in the proper maintenance of fungal morphology and formation of conidia (T. Oka, T. Hamaguchi, Y. Sameshima, M. Goto, and K. Furukawa, Microbiology 150:1973-1982, 2004). In the present paper, we describe the characterization of the pmtA paralogues pmtB and pmtC. PmtB and PmtC were classified as members of the PMT1 and PMT4 subfamilies, respectively. A pmtB disruptant showed wild-type (wt) colony formation at 30°C but slightly repressed growth at 42°C. Conidiation of the pmtB disruptant was reduced to approximately 50% of that of the wt strain; in addition, hyperbranching of hyphae indicated that PmtB is involved in polarity maintenance. A pmtA and pmtB double disruptant was viable but very slow growing, with morphological characteristics that were cumulative with respect to either single disruptant. Of the three single pmt mutants, the pmtC disruptant showed the highest growth repression; the hyphae were swollen and frequently branched, and the ability to form conidia under normal growth conditions was lost. Recovery from the aberrant hyphal structures occurred in the presence of osmotic stabilizer, implying that PmtC is responsible for the maintenance of cell wall integrity. Osmotic stabilization at 42°C further enabled the pmtC disruptant to form conidiophores and conidia, but they were abnormal and much fewer than those of the wt strain. Apart from the different, abnormal phenotypes, the three pmt disruptants exhibited differences in their sensitivities to antifungal reagents, mannosylation activities, and glycoprotein profiles, indicating that PmtA, PmtB, and PmtC perform unique functions during cell growth.
* Corresponding author. Mailing address: Department of Bioscience and Biotechnology, Faculty of Agriculture, Kyushu University, 6-10-1 Hakozaki, Fukuoka 812-8581, Japan. Phone and fax: 81-92-642-3959. E-mail: mgoto{at}brs.kyushu-u.ac.jp
Published ahead of print on 31 July 2009.
Supplemental material for this article may be found at http://ec.asm.org/.
Present address: Faculty of Biotechnology and Life Science, Sojo University, Kumamoto, Japan.
Eukaryotic Cell, October 2009, p. 1465-1474, Vol. 8, No. 10
1535-9778/09/$08.00+0 doi:10.1128/EC.00371-08
Copyright © 2009, American Society for Microbiology. All Rights Reserved.
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