The multiple-stress responsive plastid sigma factor, SIG5, directs activation of the psbD blue light-responsive promoter (BLRP) in Arabidopsis thaliana.
Transcription in higher plant plastids is performed by two types of RNA polymerases called NEP and PEP, and expression of photosynthesis genes in chloroplasts is largely dependent on PEP, a eubacteria-type multi-subunit enzyme. The transcription specificity of PEP is modulated by six nuclear-encoded sigma factors (SIG1 to SIG6) in Arabidopsis thaliana. Here, we show that one of the six sigma factors, SIG5, is induced under various stress conditions, such as high light, low temperature, high salt and high osmotic conditions. Interestingly, transcription from the psbD blue light-responsive promoter (psbD-BLRP) was activated by not only light but also various stresses, and the transcription and the transcriptional activation of psbD-BLRP were abolished in a sig5-2 mutant. This suggests that the PEP holoenzyme containing SIG5 transcribes the psbD-BLRP in response to multiple stresses. Since the seed germination under saline conditions and recovery from damage to the PSII induced by high light were delayed in the sig5-2 mutant, we postulate that SIG5 protects plants from stresses by enhancing repair of the PSII reaction center.
Nagashima
Akitomo
A
Laboratory of Molecular Genetics, Department of Molecular Biology, Institute of Molecular and Cellular Biosciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo, 113-0032 Japan.
Hanaoka
Mitsumasa
M
Shikanai
Toshiharu
T
Fujiwara
Makoto
M
Kanamaru
Kengo
K
Takahashi
Hideo
H
Tanaka
Kan
K
D017360:Arabidopsis / Q000235:genetics* / Q000378:metabolism / Q000528:radiation effects; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D003624:Darkness; D003681:Dehydration; D018506:Gene Expression Regulation, Plant; D008027:Light; D045332:Photosystem II Protein Complex / Q000378:metabolism*; D030821:Plants, Genetically Modified; D018087:Plastids / Q000235:genetics* / Q000378:metabolism / Q000528:radiation effects; D011401:Promoter Regions, Genetic; D012808:Sigma Factor / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction; D012965:Sodium Chloride / Q000378:metabolism; D013696:Temperature; D014158:Transcription, Genetic
D029681:Arabidopsis Proteins; D045332:Photosystem II Protein Complex; C479885:PsbD protein, Arabidopsis; C486979:Sig5 protein, Arabidopsis; D012808:Sigma Factor; D012965:Sodium Chloride