Host-to-pathogen gene transfer facilitated infection of insects by a pathogenic fungus

Metarhizium robertsii is a plant root colonizing fungus that is also an insect pathogen. Its entomopathogenicity is a characteristic that was acquired during evolution from a plant endophyte ancestor. This transition provides a novel perspective on how new functional mechanisms important for host sw...

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Bibliographic Details
Published in:PLoS pathogens 2014-04, Vol.10 (4), p.e1004009-e1004009
Main Authors: Zhao, Hong, Xu, Chuan, Lu, Hsiao-Ling, Chen, Xiaoxuan, St Leger, Raymond J, Fang, Weiguo
Format: Article
Language:English
Subjects:
Animals
Beauveria - genetics
Beauveria - metabolism
Biology and Life Sciences
Carrier Proteins - biosynthesis
Carrier Proteins - genetics
Cholesterol - metabolism
Deoxyribonucleic acid
DNA
Fungal Proteins - biosynthesis
Fungal Proteins - genetics
Fungi
Fungi, Pathogenic
Gene expression
Gene Transfer, Horizontal - physiology
Genes
Genetic aspects
Genetic engineering
Genetic research
Genomes
Health aspects
Herbicides
Host-parasite relationships
Host-Pathogen Interactions - physiology
Insects
Medicine and Health Sciences
Metarhizium - physiology
Microbiological research
Moths - metabolism
Moths - microbiology
Phylogenetics
Phylogeny
Sterols
Trees
Tropical diseases
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Summary:Metarhizium robertsii is a plant root colonizing fungus that is also an insect pathogen. Its entomopathogenicity is a characteristic that was acquired during evolution from a plant endophyte ancestor. This transition provides a novel perspective on how new functional mechanisms important for host switching and virulence have evolved. From a random T-DNA insertion library, we obtained a pathogenicity defective mutant that resulted from the disruption of a sterol carrier gene (Mr-npc2a). Phylogenetic analysis revealed that Metarhizium acquired Mr-npc2a from an insect by horizontal gene transfer (HGT). Mr-NPC2a binds to cholesterol, an animal sterol, rather than the fungal sterol ergosterol, indicating it retains the specificity of insect NPC2 proteins. Mr-NPC2a is an intracellular protein and is exclusively expressed in the hemolymph of living insects. The disruption of Mr-npc2a reduced the amount of sterol in cell membranes of the yeast-like hyphal bodies that facilitate dispersal in the host body. These were consequently more susceptible to insect immune responses than the wild type. Transgenic expression of Mr-NPC2a increased the virulence of Beauveria bassiana, an endophytic insect-pathogenic fungus that lacks a Mr-NPC2a homolog.
ISSN:1553-7374
1553-7366
1553-7374
DOI:10.1371/journal.ppat.1004009