Abstract
Chloroplasts have their own DNA and gene expression systems. In order to study transcriptional regulation, biochemical and genetic approaches have been historically used. However, biochemical approaches does not usually demonstrate functions under physiological conditions, and genetic approaches may include some indirect effects, which make it difficult to understand specific regulation by the transcription factors. Chromatin immunoprecipitation (ChIP) is a powerful and useful tool that can obtain information for binding sites for transcription factors, and directly detect dynamic changes of their interaction patterns in vivo.
To further understand transcriptional regulation in Arabidopsis thaliana chloroplasts, we here developed ChIP-based method, and analyzed binding pattern of SIG5, a stress-induced chloroplast sigma factor. We found SIG5 specifically binds to target promoters such as psbA or psbD BLRP, and this binding depends on several kinds of stress conditions. This result suggests that ChIP analysis is useful to understand transcriptional regulation of chloroplast genes, which can overcome several problems from traditional methods.
