| Research Abstract |
1. Using rpoS-deficient (rpoS:: Tn10) strains, an rpoS-dependent katE promoter was delimited in a region different from that previously reported by others. Furthermore, in the promoter region a -10 consensus hexamer sequence was found, but ?35 sequence was not. A carboxy-terminal region responsible for the σ ィイD138ィエD1-speeific salt-tolerance was identified by in vitro transcription experiments and named CTE (carboxy-terminal element). 2. Group 2 sigma factors of cyanobacterium Synechococcus sp. JPCC7942 were shown to recognize E. coli canonical promoters as well as cyanobacterial common promoters by in vitro, experiments. A proteome analysis, of Synechocystis sp. PCC6803 was performed and it was suggested that sigD and sigE genes were involved in the induction of specific genes during nitrogen-deficient growth condition. 3. Multiple nuclear genes (sig) encoding plastid RNA polymerase sigma factors were identified from red algae, Cyanidium caladium RK-1 and higher plants including Arabidopsis thaliana, tobacco and rice. Structural and functional analyses of these genes were carried out. The overexpressed and purified gene products were shown to have sigma activity in vitro. For A. thaliana, three new sig genes, named sigD, sigE, and sigE, besides sigA, sigB and sigC, were identified and chromosomal locations of these genes were determined. Furthermore, using uid and GFP gene fusion and transformation into Arabidopsis plants, light inducibility, localization of gene products and spacial and temporal expression of these genes during plastid development were analyzed.
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