Sequencing, chromosomal inactivation, and functional expression in Escherichia coli of ppsR, a gene which represses carotenoid and bacteriochlorophyll synthesis in Rhodobacter sphaeroides.

摘要: Sequencing of a DNA fragment that causes trans suppression bacteriochlorophyll and carotenoid levels in Rhodobacter sphaeroides revealed two genes: orf-192 ppsR. The ppsR gene alone is sufficient for photopigment suppression. Inactivation the R. chromosomal copy results overproduction both pigments. deduced 464-amino-acid protein product homologous to CrtJ capsulatus contains helix-turn-helix domain found various DNA-binding proteins. Removal renders PpsR nonfunctional. promoter located within coding region upstream gene. When this replaced by lacZ promoter, expressed Escherichia coli. An carrying crtD', -E, -F bchC, -X, -Y, -Z' exhibited putative activity E. This could be suppressed coli sphaeroides. These suggest transcriptional repressor. It potentially act binding regulatory palindrome 5' flanking regions number photosynthesis genes.