GPCR-bigrams: Enigmatic signaling components in oomycetes

Abstract

Oomycetes are diverse eukaryotic microorganisms, comprising important pathogens as well as free-living saprophytes [1]. Plant pathogenic oomycetes cause enormous yield losses in crop plants but also threaten natural vegetation. Phytophthora infestans, the causal agent of potato late blight, is without a doubt the most (in)famous. Other important plant pathogenic oomycetes include downy mildews and Albugo [2]. Animal pathogenic oomycetes (such as Saprolegnia, Aphanomyces, and Pythium) primarily affect marine organisms such as fish and crustaceans but can also cause harmful diseases in humans and cattle. Here, we outline unique features of oomycetes and their cellular signaling systems. We focus on one particularly interesting class of signaling components, the so-called GPCR-bigrams, in which a typical signaling domain is preceded by a G-protein coupled receptor (GPCR) domain and propose future directions to elucidate the function and activity of this exceptional group of signaling proteins.