Functional analysis of glycoside hydrolase family 18 and 20 genes in Neurospora crassa.
Glycoside hydrolase family 18 contains hydrolytic enzymes with chitinase or endo-N-acetyl-β-D-glucosaminidase (ENGase) activity, while glycoside hydrolase family 20 contains enzymes with β-N-acetylhexosaminidase (NAGase) activity. Chitinases and NAGases are involved in chitin degradation. Chitinases are phylogenetically divided into three main groups (A, B and C), each further divided into subgroups. In this study, we investigated the functional role of 10 Neurospora crassa genes that encode chitinases, 2 genes that encode ENGases and 1 gene that encode a NAGase, using gene deletion and gene expression techniques. No phenotypic effects were detected for any of the studied group A chitinase gene deletions. Deletion of the B group member chit-1 resulted in reduced growth rate compared with the wild type (WT) strain. In combination with the presence of a predicted glycosylphosphatidylinositol anchor motif in the C-terminal of chit-1, indicating cell wall localization, these data suggest a role in cell wall remodeling during hyphal growth for chit-1. Deletion of the ENGase gene gh18-10 resulted in reduced growth rate compared with WT, increased conidiation, and increased abiotic stress tolerance. In addition, Δgh18-10 strains displayed lower secretion of extracellular proteins compared to WT and reduced levels of extracellular protease activity. The connection between gh18-10 ENGase activity and the endoplasmic reticulum associated protein degradation process, a stringent quality control of glycoprotein maturation, is discussed. N. crassa group C chitinase genes gh18-6 and gh18-8 were both induced during fungal-fungal interactions. However, gh18-6 was only induced during interspecific interactions, while gh18-8 displayed the highest induction levels during self-self interactions. These results provide new information on functional differentiation of fungal chitinases.
Uppsala BioCenter, Department of Forest Mycology and Plant Pathology, Swedish University of Agricultural Sciences, 75007 Uppsala, Sweden. georgios.tzelepis@slu.se
Georgios D
GD
Tzelepis
Petter
P
Melin
Dan Funck
DF
Jensen
Jan
J
Stenlid
Magnus
M
Karlsson
D002473:Cell Wall / Q000737:chemistry / Q000201:enzymology / Q000235:genetics; D005656:Fungal Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D006026:Glycoside Hydrolases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D005810:Multigene Family; D009492:Neurospora crassa / Q000737:chemistry / Q000201:enzymology* / Q000235:genetics; D017434:Protein Structure, Tertiary; D021381:Protein Transport
D005656:Fungal Proteins; D006026:Glycoside Hydrolases