Comparative proteomic analysis of an Aspergillus fumigatus mutant deficient in glucosidase I (AfCwh41).
Alpha-glucosidase I regulates trimming of the terminal alpha-1,2-glucose residue in the N-glycan processing pathway, which plays an important role in quality control systems in mammalian cells. Previously, we identified the gene encoding alpha-glucosidase I in the opportunistic human fungal pathogen Aspergillus fumigatus, namely Afcwh41. Deletion of the Afcwh41 gene results in a severe reduction of conidia formation, a temperature-sensitive deficiency of cell wall integrity, and abnormalities of polar growth and septation. An upregulation of the genes encoding Rho-type GTPases was also observed, which suggests activation of the cell wall integrity pathway in the mutant. Using 2D gel analysis, we revealed that the proteins involved in protein assembly, ubiquitin-mediated degradation and actin organization are altered in the DeltaAfcwh41 mutant. Evidence was obtained for a defect in the polarized localization of the actin cytoskeleton in the mutant. Our results suggest that blocking of the glucose trimming in A. fumigatus might induce accumulation of misfolded proteins in the endoplasmic reticulum; these misfolded proteins are probably required for cell wall synthesis and thus activate the cell wall integrity pathway, which then causes the abnormal polarity associated with the DeltaAfcwh41 mutant.
Zhang
Lei
L
Key Laboratory of Systematic Mycology and Lichenology, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China.
Feng
Deqin
D
State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China.
Fang
Wenxia
W
Key Laboratory of Systematic Mycology and Lichenology, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China.
Ouyang
Haomiao
H
Key Laboratory of Systematic Mycology and Lichenology, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China.
Luo
Yuanming
Y
State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China.
Du
Ting
T
Key Laboratory of Systematic Mycology and Lichenology, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China.
Jin
Cheng
C
Key Laboratory of Systematic Mycology and Lichenology, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China.
D000199:Actins / Q000378:metabolism; D001232:Aspergillus fumigatus / Q000187:drug effects / Q000502:physiology*; D037281:Calnexin / Q000096:biosynthesis; D016764:Cell Polarity; D002473:Cell Wall / Q000378:metabolism; D004229:Dithiothreitol / Q000494:pharmacology; D015180:Electrophoresis, Gel, Two-Dimensional; D004721:Endoplasmic Reticulum / Q000187:drug effects; D005656:Fungal Proteins / Q000096:biosynthesis; D008840:Microfilament Proteins / Q000096:biosynthesis; D017510:Protein Folding; D020543:Proteome / Q000032:analysis*; D013172:Spores, Fungal / Q000378:metabolism; D053719:Tandem Mass Spectrometry; D000520:alpha-Glucosidases / Q000172:deficiency*; D020741:rho GTP-Binding Proteins / Q000096:biosynthesis
D000199:Actins; D005656:Fungal Proteins; D008840:Microfilament Proteins; D020543:Proteome; D037281:Calnexin; C042059:glucosidase I; D000520:alpha-Glucosidases; D020741:rho GTP-Binding Proteins; D004229:Dithiothreitol