A Serpin Released by an Entomopathogen Impairs Clot Formation in Insect Defense System

被引：46

作者：

Toubarro, Duarte ^{[1
]}

Avila, Monica M. ^{[1
]}

Hao, YouJin ^{[1
]}

Balasubramanian, Natesan ^{[1
]}

Jing, Yingjun ^{[1
]}

Montiel, Rafael ^{[2
]}

Faria, Tiago Q. ^{[3
]}

Brito, Rui M. ^{[3
]}

Simoes, Nelson ^{[1
]}

机构：

[1] Univ Azores, Ctr Invest Recursos Nat, Ctr Biotecnol Acores, Associate Lab Inst Biotechnol & Bioengn,Dept Biol, Ponta Delgada, Portugal

[2] Inst Politecn Nacl, Lab Nacl Genom Biodiversidad, Ctr Invest & Estudios Avanzados, Guanajuato, Mexico

[3] Univ Coimbra, Ctr Neurosci & Cell Biol, Coimbra, Portugal

来源：

PLOS ONE | 2013年 / 8卷 / 07期

关键词：

PROTEIN SECONDARY STRUCTURE; STEINERNEMA; HOST; COAGULATION; ENCAPSULATION; CARPOCAPSAE; SUPPRESSION; XENORHABDUS;

D O I：

10.1371/journal.pone.0069161

中图分类号：

O [数理科学和化学]; P [天文学、地球科学]; Q [生物科学]; N [自然科学总论];

学科分类号：

07 ; 0710 ; 09 ;

摘要：

Steinernema carpocapsae is an entomopathogenic nematode widely used for the control of insect pests due to its virulence, which is mainly attributed to the ability the parasitic stage has to overcome insect defences. To identify the mechanisms underlying such a characteristic, we studied a novel serpin-like inhibitor (sc-srp-6) that was detected in a transcriptome analysis. Recombinant Sc-SRP-6 produced in Escherichia coli had a native fold of serpins belonging to the alpha-1-peptidase family and exhibited inhibitory activity against trypsin and alpha-chymotrypsin with Ki of 0.426x10(-7) M and 1.226x10(-7) M, respectively. Functional analysis revealed that Sc-SRP-6 inhibits insect digestive enzymes, thus preventing the hydrolysis of ingested particles. Moreover, Sc-SRP-6 impaired the formation of hard clots at the injury site, a major insect defence mechanism against invasive pathogens. Sc-SRP-6 does not prevent the formation of clot fibres and the activation of prophenoloxidases but impairs the incorporation of the melanin into the clot. Binding assays showed a complex formation between Sc-SRP-6 and three proteins in the hemolymph of lepidopteran required for clotting, apolipophorin, hexamerin and trypsin-like, although the catalytic inhibition occurred exclusively in trypsin-like. This data allowed the conclusion that Sc-SRP-6 promotes nematode virulence by inhibiting insect gut juices and by impairing immune clot reaction.

引用

页数：12

共 47 条

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