title: Structure-function analyses of the Pth11 receptor reveal an important role for CFEM motif and redox regulation in rice blast.
abstract: The interaction of Magnaporthe oryzae, the rice blast fungus, and rice begins when M. oryzae establishes contact with the host plant surface. On perception of appropriate surface signals, M. oryzae forms appressoria and initiates host invasion. Pth11, an important G-protein-coupled receptor necessary for appressorium formation in M. oryzae, contains seven transmembrane regions and a CFEM (common in several fungal extracellular membrane proteins) domain with the characteristic eight cysteine residues. We focused on gaining further insight into the role of the CFEM domain in the putative surface sensing/response function of Pth11. Increased/constitutive expression of CFEM resulted in precocious, albeit defective, appressoria formation in wild-type M. oryzae. The Pth11C63A/C65Amutant, probably with disrupted disulfide bonds in the CFEM, showed delayed appressorium formation and reduced virulence. Furthermore, the accumulation of reactive oxygen species (ROS) was found to be altered in the pth11Δ strain. Strikingly, antioxidant treatment induced appressorium formation in pth11Δ. The Gα subunit MagB and the mitogen-activated protein (MAP) kinase Pmk1 were required for the formation of antioxidant-induced appressoria. We conclude that the CFEM domain of Pth11 is required for proper development of the appressoria, appressoria-like structures and pathogenicity. Highly regulated ROS homeostasis is important for Pth11-mediated appressorium formation in M. oryzae.
authors.affiliation: Temasek Life Sciences Laboratory, and Department of Biological Sciences, 1 Research Link, National University of Singapore, 117604, Singapore.|State Key Laboratory of Rice Biology, China National Rice Research Institute, Hangzhou, 117596, China.
authors.forename: Yanjun
authors.initials: Y
authors.lastname: Kou
authors.affiliation: Department of Biochemistry, National University of Singapore, 8 Medical Drive, 117596, Singapore.
authors.forename: Yi Han
authors.initials: YH
authors.lastname: Tan
authors.affiliation: Temasek Life Sciences Laboratory, and Department of Biological Sciences, 1 Research Link, National University of Singapore, 117604, Singapore.
authors.forename: Ravikrishna
authors.initials: R
authors.lastname: Ramanujam
authors.affiliation: Temasek Life Sciences Laboratory, and Department of Biological Sciences, 1 Research Link, National University of Singapore, 117604, Singapore.|School of Biological Sciences, Nanyang Technological University, 637551, Singapore.
authors.forename: Naweed I
authors.initials: NI
authors.lastname: Naqvi
mesh_terms: D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D000975:Antioxidants / Q000494:pharmacology; D017124:Conserved Sequence; D003545:Cysteine; D005656:Fungal Proteins / Q000737:chemistry* / Q000378:metabolism*; D044385:GTP-Binding Protein alpha Subunits / Q000378:metabolism; D057927:Hydrophobic and Hydrophilic Interactions; D020082:Magnaporthe / Q000378:metabolism* / Q000472:pathogenicity; D012275:Oryza / Q000382:microbiology*; D010084:Oxidation-Reduction; D010935:Plant Diseases / Q000382:microbiology*; D000072417:Protein Domains; D017382:Reactive Oxygen Species / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects; D013172:Spores, Fungal / Q000187:drug effects / Q000254:growth & development; D013329:Structure-Activity Relationship; D013347:Subcellular Fractions / Q000378:metabolism
chemical_list: D000975:Antioxidants; D005656:Fungal Proteins; D044385:GTP-Binding Protein alpha Subunits; D017382:Reactive Oxygen Species; D003545:Cysteine
keywords: 
  Magnaporthe oryzae
  ; CFEM domain; Pth11; antioxidant; appressorium; redox regulation; rice blast; surface recognition