title: Aberrant protein N-glycosylation impacts upon infection-related growth transitions of the haploid plant-pathogenic fungus Mycosphaerella graminicola.
abstract: The ascomycete fungus Mycosphaerella graminicola is the causal agent of Septoria Tritici Blotch disease of wheat and can grow as yeast-like cells or as hyphae depending on environmental conditions. Hyphal growth is however essential for successful leaf infection. A T-DNA mutagenesis screen performed on haploid spores identified a mutant, which can undergo yeast-like growth but cannot switch to hyphal growth. For this reason the mutant was non-pathogenic towards wheat leaves. The gene affected, MgAlg2, encoded a homologue of Saccharomyces cerevisiae ScAlg2, an alpha-1,2-mannosyltransferase, which functions in the early stages of asparagine-linked protein (N-) glycosylation. Targeted gene deletion and complementation experiments confirmed that loss of MgAlg2 function prevented the developmental growth switch. MgAlg2 was able to functionally complement the S. cerevisiae ScAlg2-1 temperature sensitive growth phenotype. Spores of ΔMgAlg2 mutants were hypersensitive to the cell wall disrupting agent Calcofluor white and produced abnormally hypo-N-glycosylated proteins. Gene expression, proteome and glycoproteome analysis revealed that ΔMgAlg2 mutant spores show responses typically associated with the accumulation of mis-folded proteins. The data presented highlight key roles for protein N-glycosylation in regulating the switch to hyphal growth, possibly as a consequence of maintaining correct folding and localization of key proteins involved in this process.
authors.affiliation: Department of Plant Pathology and Microbiology, Rothamsted Research, Harpenden, Herts AL52JQ, UK.
authors.forename: Juliet
authors.initials: J
authors.lastname: Motteram
authors.forename: Alison
authors.initials: A
authors.lastname: Lovegrove
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Pirie
authors.forename: Justin
authors.initials: J
authors.lastname: Marsh
authors.forename: Jean
authors.initials: J
authors.lastname: Devonshire
authors.forename: Allison
authors.initials: A
authors.lastname: van de Meene
authors.forename: Kim
authors.initials: K
authors.lastname: Hammond-Kosack
authors.forename: Jason J
authors.initials: JJ
authors.lastname: Rudd
mesh_terms: D000595:Amino Acid Sequence; D001203:Ascomycota / Q000254:growth & development / Q000378:metabolism* / Q000472:pathogenicity; D017353:Gene Deletion; D020869:Gene Expression Profiling; D005816:Genetic Complementation Test; D006031:Glycosylation; D025301:Hyphae / Q000254:growth & development / Q000378:metabolism* / Q000472:pathogenicity; D008364:Mannosyltransferases / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D016254:Mutagenesis, Insertional; D010935:Plant Diseases / Q000382:microbiology*; D018515:Plant Leaves / Q000382:microbiology; D020543:Proteome / Q000032:analysis; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics; D017386:Sequence Homology, Amino Acid; D014908:Triticum / Q000382:microbiology*; D014774:Virulence; D037521:Virulence Factors / Q000235:genetics / Q000378:metabolism*
chemical_list: D020543:Proteome; D029701:Saccharomyces cerevisiae Proteins; D037521:Virulence Factors; C083733:ALG2 protein, S cerevisiae; D008364:Mannosyltransferases