title: The MrCYP52 cytochrome P450 monoxygenase gene of Metarhizium robertsii is important for utilizing insect epicuticular hydrocarbons.
abstract: Fungal pathogens of plants and insects infect their hosts by direct penetration of the cuticle. Plant and insect cuticles are covered by a hydrocarbon-rich waxy outer layer that represents the first barrier against infection. However, the fungal genes that underlie insect waxy layer degradation have received little attention. Here we characterize the single cytochrome P450 monoxygenase family 52 (MrCYP52) gene of the insect pathogen Metarhizium robertsii, and demonstrate that it encodes an enzyme required for efficient utilization of host hydrocarbons. Expressing a green florescent protein gene under control of the MrCYP52 promoter confirmed that MrCYP52 is up regulated on insect cuticle as well as by artificial media containing decane (C10), extracted cuticle hydrocarbons, and to a lesser extent long chain alkanes. Disrupting MrCYP52 resulted in reduced growth on epicuticular hydrocarbons and delayed developmental processes on insect cuticle, including germination and production of appressoria (infection structures). Extraction of alkanes from cuticle prevented induction of MrCYP52 and reduced growth. Insect bioassays against caterpillars (Galleria mellonella) confirmed that disruption of MrCYP52 significantly reduces virulence. However, MrCYP52 was dispensable for normal germination and appressorial formation in vitro when the fungus was supplied with nitrogenous nutrients. We conclude therefore that MrCYP52 mediates degradation of epicuticular hydrocarbons and these are an important nutrient source, but not a source of chemical signals that trigger infection processes.
authors.affiliation: State Key Laboratory of Bioreactor Engineering, Newworld Institute of Biotechnology, East China University of Science and Technology, Shanghai, China.
authors.forename: Liangcai
authors.initials: L
authors.lastname: Lin
authors.forename: Weiguo
authors.initials: W
authors.lastname: Fang
authors.forename: Xinggang
authors.initials: X
authors.lastname: Liao
authors.forename: Fengqing
authors.initials: F
authors.lastname: Wang
authors.forename: Dongzhi
authors.initials: D
authors.lastname: Wei
authors.forename: Raymond J
authors.initials: RJ
authors.lastname: St Leger
mesh_terms: D000473:Alkanes / Q000378:metabolism; D000595:Amino Acid Sequence; D000818:Animals; D001681:Biological Assay; D003577:Cytochrome P-450 Enzyme System / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D005656:Fungal Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D015966:Gene Expression Regulation, Fungal; D005800:Genes, Fungal / Q000235:genetics*; D049452:Green Fluorescent Proteins / Q000378:metabolism; D006838:Hydrocarbons / Q000378:metabolism*; D007313:Insecta / Q000378:metabolism*; D034582:Integumentary System / Q000502:physiology*; D052981:Metarhizium / Q000201:enzymology* / Q000235:genetics* / Q000254:growth & development; D008969:Molecular Sequence Data; D010802:Phylogeny; D016415:Sequence Alignment; D013997:Time Factors
chemical_list: D000473:Alkanes; D005656:Fungal Proteins; D006838:Hydrocarbons; D049452:Green Fluorescent Proteins; D003577:Cytochrome P-450 Enzyme System