BcIqg1, a fungal IQGAP homolog, interacts with NADPH oxidase, MAP kinase and calcium signaling proteins and regulates virulence and development in Botrytis cinerea. Issue 2 (29th April 2016)

• Record Type: Journal Article
• Authors: Marschall, Robert; Tudzynski, Paul
• Is Part Of: Molecular microbiology. Volume 101:Issue 2(2016)
• Page Start: 281
• Page End: 298
• Publication Date: 2016-04-29
• Subjects: Molecular microbiology -- Periodicals; 572.829
• DOI: 10.1111/mmi.13391
• Languages: English
• ISSNs: 0950-382X

Abstract

Summary: NADPH oxidases (Nox) produce reactive oxygen species (ROS) in multicellular eukaryotic organisms. They trigger defense reactions ('oxidative burst') – in phagocytes and plant cells –, and are involved in a broad range of differentiation processes. Fungal Nox‐complexes play a central role in vegetative, sexual and pathogenic processes. In contrast to mammalian systems, knowledge is limited about composition, localisation and connection to major signaling cascades in fungi. Here, we characterize a fungal homolog of the RasGAP scaffold protein IQGAP, which links several major signaling processes, including Nox in mammalian cell lines. We show that BcIqg1 interacts directly with a cytosolic, regulatory component (BcRac) and a membrane‐associated subunit (BcNoxD) of a Nox‐complex in the pathogen Botrytis cinerea . Thus, this protein may be a scaffold that mediates interaction of the catalytic subunits with the regulator BcNoxR. The protein interacts with modules of the MAP kinase‐ and calcium‐dependent signaling pathways. Functional analysis of BcIqg1 substantiated its involvement in different signaling pathways. It mediates the Ca 2+ ‐triggered nuclear translocation of − BcCRZ1 and the MAP kinase BcBmp1. BcIqg1 is involved in resistance against oxidative and membrane stress and is required for several developmental processes including formation of sclerotia, conidial anastomosis tubes and infection cushions as well as for virulence. Abstract : A homolog of the RasGAP scaffold protein IQGAP links cytosolic and catalytic NADPHoxidase subunits in the grey mold fungus Botrytis cinerea, interacts with modules of the MAP kinase‐ and calcium‐dependent signaling pathways, and is involved in resistance against oxidative and membrane stress and in several developmental processes such as formation of sclerotia, conidial anastomosis tubes and infection cushions as well as in virulence.