The gene for the heat-shock protein HSP100 is induced by blue light and heat-shock in the fungus Phycomyces blakesleeanus.
We cloned and sequenced the Phycomyces hspA gene. The hspA gene product is a 901-amino-acid protein member of the clpB/HSP100 family. HSP100 proteins are ATPases involved in high-temperature tolerance, proteolysis, and protein disaggregation. Phycomyces HSP100 is composed of a domain presumably involved in protein-protein interactions and two ATP-binding domains. The hspA promoter contains three heat-shock elements that are presumably involved in the activation of hspA after heat-shock. In addition, four short sequences are present in the hspA promoter and in the promoter of the photoinducible genes carB and carRA; and these are candidates as binding sites for light-regulated transcription factors. Blue light can increase transcription of the hspA gene 10-fold, with a threshold of 1 J/m2. The threshold for hspA photoactivation is 10(4) times higher than the thresholds for blue-light regulation of sporangiophore development and photocarotenogenesis, which suggests that there are differences in the photosensory systems for gene photoactivation and mycelial photoresponses. A heat-shock of 30 min at 34 degrees C or 42 degrees C increased hspA gene activity 160-fold. The differences in maximum hspA gene transcription by blue light and heatshock suggest the presence of different regulatory mechanisms.
Rodríguez-Romero
Julio
J
Departamento de Genética, Facultad de Biología, Universidad de Sevilla, Avenida Reina Mercedes 6, Apartado 1095, 41080 Sevilla, Spain.
Corrochano
Luis M
LM
D000251:Adenosine Triphosphatases / Q000378:metabolism; D000595:Amino Acid Sequence; D001426:Bacterial Proteins; D001483:Base Sequence; D001665:Binding Sites; D002338:Carotenoids / Q000096:biosynthesis / Q000528:radiation effects; D003001:Cloning, Molecular; D015966:Gene Expression Regulation, Fungal / Q000528:radiation effects*; D006360:Heat-Shock Proteins / Q000235:genetics* / Q000378:metabolism*; D018869:Heat-Shock Response; D006358:Hot Temperature; D008027:Light; D008969:Molecular Sequence Data; D010777:Photochemistry; D010800:Phycomyces / Q000737:chemistry* / Q000528:radiation effects; D011401:Promoter Regions, Genetic / Q000235:genetics; D017386:Sequence Homology, Amino Acid; D014158:Transcription, Genetic
D001426:Bacterial Proteins; D006360:Heat-Shock Proteins; D002338:Carotenoids; D000251:Adenosine Triphosphatases