Structure and function of DNA-binding proteins that are present in plastid envelope.

点击翻译按钮获取中文摘要

1.Dynamics of cpDNA.Observation by fluorescence microscopy of the binding of cpDNA with plastid envelope at various stages of development of etioplast and chloroplast indicated that cpDNA binds to plastid envelope in young plastids active in division and that this binding was not affected by light or the presence of thylakoid membrane.2.Identification of a cpDNA-specific DNA-binding protein in plastid envelope. A 130 kDa DNA-binding protein was detected in plastid envelop by South-western technique. The protein named PEND protein was localized in the inner envelope, and was able to bind to several (at least four) distinct regions of cpDNA.PEND protein was detected in the envelope of young plastid but not in the envelop of mature chloroplast.3.Effort to purify PEND protein. PEND protein was partially affinty-purified using a biotin-labelled DNA probe and streptavidin-coated magnetic particles. The protein was detected as a 115kDa polypeptide in the standard SDS-PAGE.4.cDNA cloning of plastid DNA-binding proteins. A series of South-western screening yielded 3 clones of cDNA.The antibody against one of these proteins (PD1) detected 50kDa and 87kDa polypeptides in the plastid. The accumulation of these polypeptides was markedly reduced by a cytokinin.