A Ras GTPase associated protein is involved in the phototropic and circadian photobiology responses in fungi.
Light is an environmental signal perceived by most eukaryotic organisms and that can have major impacts on their growth and development. The MadC protein in the fungus Phycomyces blakesleeanus (Mucoromycotina) has been postulated to form part of the photosensory input for phototropism of the fruiting body sporangiophores, but the madC gene has remained unidentified since the 1960s when madC mutants were first isolated. In this study the madC gene was identified by positional cloning. All madC mutant strains contain loss-of-function point mutations within a gene predicted to encode a GTPase activating protein (GAP) for Ras. The madC gene complements the Saccharomyces cerevisiae Ras-GAP ira1 mutant and the encoded MadC protein interacts with P. blakesleeanus Ras homologs in yeast two-hybrid assays, indicating that MadC is a regulator of Ras signaling. Deletion of the homolog in the filamentous ascomycete Neurospora crassa affects the circadian clock output, yielding a pattern of asexual conidiation similar to a ras-1 mutant that is used in circadian studies in N. crassa. Thus, MadC is unlikely to be a photosensor, yet is a fundamental link in the photoresponses from blue light perceived by the conserved White Collar complex with Ras signaling in two distantly-related filamentous fungal species.
Division of Cell Biology and Biophysics, School of Biological Sciences, University of Missouri-Kansas City, Kansas City, USA.
Silvia
S
Polaino
Laboratorio Nacional de Genómica para la Biodiversidad, CINVESTAV Sede Irapuato, Irapuato, Guanajuato, Mexico.
José M
JM
Villalobos-Escobedo
Division of Cell Biology and Biophysics, School of Biological Sciences, University of Missouri-Kansas City, Kansas City, USA.
Viplendra P S
VP
Shakya
Departamento de Genética, Universidad de Sevilla, Sevilla, Spain.
Alejandro
A
Miralles-Durán
Division of Cell Biology and Biophysics, School of Biological Sciences, University of Missouri-Kansas City, Kansas City, USA.
Suman
S
Chaudhary
Departamento de Microbiología y Genética, Universidad de Salamanca, Salamanca, Spain.
Catalina
C
Sanz
Departamento de Microbiología y Genética, Universidad de Salamanca, Salamanca, Spain.
Mahdi
M
Shahriari
Departamento de Genética, Universidad de Sevilla, Sevilla, Spain.
Eva M
EM
Luque
Departamento de Microbiología y Genética, Universidad de Salamanca, Salamanca, Spain.
Arturo P
AP
Eslava
Departamento de Genética, Universidad de Sevilla, Sevilla, Spain.
Luis M
LM
Corrochano
Laboratorio Nacional de Genómica para la Biodiversidad, CINVESTAV Sede Irapuato, Irapuato, Guanajuato, Mexico.
Alfredo
A
Herrera-Estrella
Division of Cell Biology and Biophysics, School of Biological Sciences, University of Missouri-Kansas City, Kansas City, USA.|School of BioSciences, University of Melbourne, Australia.
Alexander
A
Idnurm
D000483:Alleles; D001483:Base Sequence; D002874:Chromosome Mapping; D002940:Circadian Rhythm / Q000502:physiology* / Q000528:radiation effects; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism; D020869:Gene Expression Profiling; D015966:Gene Expression Regulation, Fungal / Q000528:radiation effects; D005800:Genes, Fungal; D005816:Genetic Complementation Test; D008027:Light; D000073658:Loss of Function Mutation / Q000235:genetics; D010641:Phenotype; D018462:Photobiology; D018524:Phototropism / Q000502:physiology* / Q000528:radiation effects; D010800:Phycomyces / Q000235:genetics / Q000378:metabolism* / Q000502:physiology* / Q000528:radiation effects; D012689:Sequence Homology, Nucleic Acid; D015398:Signal Transduction / Q000528:radiation effects; D014158:Transcription, Genetic / Q000528:radiation effects; D018631:ras Proteins / Q000378:metabolism*
D005656:Fungal Proteins; D018631:ras Proteins