Differential expression of G protein a and b subunit genes during development of Phytophthora infestans
Laxalt. A.M Latijnhouwers. M Hulten. M.V Govers. F
Fungal Genetics and Biology ; 2002 [Vol.36] Pages:137-146
Abstract
A G protein a subunit gene (pigpa1) and a G protein b subunit gene (pigpb1) were isolated from the oomycete Phytophthora infestans,/i>, the causal agent of potato late blight. Heterotrimeric G proteins are evolutionary conserved GTP-binding proteins that are composed of a, b, and y subunits and participate in diverse signal transduction pathways. The deduced amino acid sequence of both pigpa1 and pigpb1, showed the typical conserved motifs present in Ga or Gb proteins from other eukaryotes. Southern blot analysis revealed no additional copies of Ga or Gb subunit genes in P. infestans, suggesting that pigpa1 and pigpb1 are single copy genes. By cross-hybridization homologues of gpa1 and gpb1 were detected in other Phythophthora species. Expression analyses revealed that both genes are differentially expressed during asexual development, with the highest mRNA levels in sporangia. In mycelium, no pigpa1 mRNA was detected. Western blot analysis using a polyclonal GPA1 antibody confirmed the differential expression of pigpa1. These expression patterns suggest a role for G-protein-mediated signaling during formation and germination of asexual spores of P. infestans, developmental stages representing the initial steps of the infection process.
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