PROMOTER PREFERENCE AND LIGHT-RESPONSIVE TRANSCRIPTION OF PLASTID delta FACTORS IN ARABIDOPSIS

摘要

In chloroplasts, the primary photosynthesis-related genes, such as psbA and psbD encoding D1 and D2 proteins of the photosystem II reaction centre, are transcribed by plastid-encoded plastid RNA polymerase (PEP) (Allison et al 1996, Legen et al 2002).PEP is a niuiti-subunit RNA polymerase, whose catalytically competent core enzyme consists of the plastid-encoded subunits (alpha_2 beta beta' beta''). The promoter-specific transcription initiation requires a nuclear-encoded & factor, which assembles with PEP core to form the holoenzyme (Hu & Bogorad 1990). PEP a factors, which belong to a superfamily of E.coli delta~(70), recognize two consensus hexamers of delta~(70)-type promoter. -10 and -35 elements, such as 5'-TacaaT-3' and 5'-TTGagc-3', respectively (small letters: variable bases among the genes). Genetic and crystal structure analyses of bacterial cy-DNA complex indicate that the binding determinants of a factor to —10 and -35 elements are regions 2.4 and 4.2, respectively (Gross et al 1998, Campbell et al 2002, Murakami et al 2002).