Secretory phospholipase A2s(sPLA2s)are found in a wide range of organisms from bacteria to higher plants and animals and are involved in varied and cellular pro-cesses.However,roles of these enzymes in microbial patho...Secretory phospholipase A2s(sPLA2s)are found in a wide range of organisms from bacteria to higher plants and animals and are involved in varied and cellular pro-cesses.However,roles of these enzymes in microbial pathogens remain unclear.Here,an sPLA2(BbPLA2)was characterized in the filamentous insect pathogenic fungus,Beau-veria bassiana.BbPLA2was exclusively expressed in insect hemolymph-derived cells(hyphal bodies),and its expression was induced by insect-derived nutrients and lipids,and nutrient starvation.High levels of secretion of BbPLA2 were observed as well as its distri-bution in hyphal body lipid drops(LDs).Overexpression of BbPLA2 increased the ability of B.bassiana to utilize insect-derived nutrients and lipids,and promoted LD accumula-tion,indicating functions for BbPLA2 in mediating LD homeostasis and assimilation of insect-derived lipids.Strains overexpressing BbPLA2 showed moderately increased vir-ulence,including more efficient penetration of the insect cuticle and evasion of host im-mune responses as compared to the wild type strain.In addition,B.bassiana-activated host immune genes were downregulated in the BbPLA2 overexpression strain,but upregulated by infections with a△BbPLA2 strain.These data demonstrate that BbPLA2 contributes to LD homeostasis,assimilation of insect-derived lipids,and repression of host immune responses.展开更多
基金supported by a grant from the National Nature Science Foundation of China(31672080)。
文摘Secretory phospholipase A2s(sPLA2s)are found in a wide range of organisms from bacteria to higher plants and animals and are involved in varied and cellular pro-cesses.However,roles of these enzymes in microbial pathogens remain unclear.Here,an sPLA2(BbPLA2)was characterized in the filamentous insect pathogenic fungus,Beau-veria bassiana.BbPLA2was exclusively expressed in insect hemolymph-derived cells(hyphal bodies),and its expression was induced by insect-derived nutrients and lipids,and nutrient starvation.High levels of secretion of BbPLA2 were observed as well as its distri-bution in hyphal body lipid drops(LDs).Overexpression of BbPLA2 increased the ability of B.bassiana to utilize insect-derived nutrients and lipids,and promoted LD accumula-tion,indicating functions for BbPLA2 in mediating LD homeostasis and assimilation of insect-derived lipids.Strains overexpressing BbPLA2 showed moderately increased vir-ulence,including more efficient penetration of the insect cuticle and evasion of host im-mune responses as compared to the wild type strain.In addition,B.bassiana-activated host immune genes were downregulated in the BbPLA2 overexpression strain,but upregulated by infections with a△BbPLA2 strain.These data demonstrate that BbPLA2 contributes to LD homeostasis,assimilation of insect-derived lipids,and repression of host immune responses.
