Jiang Rays H Y, Tripathy Sucheta, Govers Francine, Tyler Brett M
Virginia Bioinformatics Institute, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061, USA.
Proc Natl Acad Sci U S A. 2008 Mar 25;105(12):4874-9. doi: 10.1073/pnas.0709303105. Epub 2008 Mar 14.
Pathogens secrete effector molecules that facilitate the infection of their hosts. A number of effectors identified in plant pathogenic Phytophthora species possess N-terminal motifs (RXLR-dEER) required for targeting these effectors into host cells. Here, we bioinformatically identify >370 candidate effector genes in each of the genomes of P. sojae and P. ramorum. A single superfamily, termed avirulence homolog (Avh) genes, accounts for most of the effectors. The Avh proteins show extensive sequence divergence but are all related and likely evolved from a common ancestor by rapid duplication and divergence. More than half of the Avh proteins contain conserved C-terminal motifs (termed W, Y, and L) that are usually arranged as a module that can be repeated up to eight times. The Avh genes belong to the most rapidly evolving part of the genome, and they are nearly always located at synteny breakpoints. The superfamily includes all experimentally identified oomycete effector and avirulence genes, and its rapid pace of evolution is consistent with a role for Avh proteins in interaction with plant hosts.
病原体分泌促进其感染宿主的效应分子。在植物致病疫霉物种中鉴定出的许多效应分子具有将这些效应分子靶向宿主细胞所需的N端基序（RXLR-dEER）。在这里，我们通过生物信息学方法在大豆疫霉和樟疫霉的每个基因组中鉴定出超过370个候选效应基因。一个称为无毒同源物（Avh）基因的单一超家族占了大多数效应分子。Avh蛋白显示出广泛的序列差异，但都相关，并且可能通过快速复制和分化从一个共同祖先进化而来。超过一半的Avh蛋白含有保守的C端基序（称为W、Y和L），这些基序通常排列成一个模块，可重复多达八次。Avh基因属于基因组中进化最快的部分，并且它们几乎总是位于同线性断点处。该超家族包括所有通过实验鉴定的卵菌效应分子和无毒基因，其快速的进化速度与Avh蛋白在与植物宿主相互作用中的作用一致。
