title: A dominant mutation in the light-oxygen and voltage2 domain vicinity impairs phototropin1 signaling in tomato.
abstract: In higher plants, blue light (BL) phototropism is primarily controlled by the phototropins, which are also involved in stomatal movement and chloroplast relocation. These photoresponses are mediated by two phototropins, phot1 and phot2. Phot1 mediates responses with higher sensitivity than phot2, and phot2 specifically mediates chloroplast avoidance and dark positioning responses. Here, we report the isolation and characterization of a Nonphototropic seedling1 (Nps1) mutant of tomato (Solanum lycopersicum). The mutant is impaired in low-fluence BL responses, including chloroplast accumulation and stomatal opening. Genetic analyses show that the mutant locus is dominant negative in nature. In dark-grown seedlings of the Nps1 mutant, phot1 protein accumulates at a highly reduced level relative to the wild type and lacks BL-induced autophosphorylation. The mutant harbors a single glycine-1484-to-alanine transition in the Hinge1 region of a phot1 homolog, resulting in an arginine-to-histidine substitution (R495H) in a highly conserved A'α helix proximal to the light-oxygen and voltage2 domain of the translated gene product. Significantly, the R495H substitution occurring in the Hinge1 region of PHOT1 abolishes its regulatory activity in Nps1 seedlings, thereby highlighting the functional significance of the A'α helix region in phototropic signaling of tomato.
authors: Repository of Tomato Genomics Resources, Department of Plant Sciences, School of Life Sciences, University of Hyderabad, Hyderabad 500046, India.
authors: Sulabha
authors: S
authors: Sharma
authors: Eros
authors: E
authors: Kharshiing
authors: Ankanagari
authors: A
authors: Srinivas
authors: Kazunori
authors: K
authors: Zikihara
authors: Satoru
authors: S
authors: Tokutomi
authors: Akira
authors: A
authors: Nagatani
authors: Hiroshi
authors: H
authors: Fukayama
authors: Reddaiah
authors: R
authors: Bodanapu
authors: Rajendra K
authors: RK
authors: Behera
authors: Yellamaraju
authors: Y
authors: Sreelakshmi
authors: Rameshwar
authors: R
authors: Sharma
mesh_terms: D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D001483:Base Sequence; D002736:Chloroplasts / Q000378:metabolism; D018548:Cotyledon / Q000502:physiology / Q000528:radiation effects; D005799:Genes, Dominant; D018546:Hypocotyl / Q000254:growth & development / Q000528:radiation effects; D008027:Light; D018551:Solanum lycopersicum / Q000235:genetics* / Q000378:metabolism* / Q000502:physiology / Q000528:radiation effects; D008958:Models, Molecular; D008969:Molecular Sequence Data; D050505:Mutant Proteins / Q000737:chemistry / Q000378:metabolism; D009154:Mutation / Q000235:genetics*; D010641:Phenotype; D056949:Phototropins / Q000737:chemistry* / Q000235:genetics* / Q000378:metabolism; D018524:Phototropism / Q000528:radiation effects; D054046:Plant Stomata / Q000502:physiology / Q000528:radiation effects; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D017386:Sequence Homology, Amino Acid; D015398:Signal Transduction / Q000528:radiation effects
chemical_list: D050505:Mutant Proteins; D056949:Phototropins