Genetic evidence that PpsR from Rhodobacter sphaeroides 2.4.1 functions as a repressor of puc and bchF expression

Abstract

The ppsR gene (R. J. Penfold and J. M. Pemberton, J. Bacteriol. 176:2869-2876, 1994) from Rhodobacter sphaeroides 2.4.1 functions as a transcriptional repressor of puc and bchF expression. The carboxy terminus of PpsR, containing the putative DNA-binding domain, by itself possesses repressor activity. Intact palindromes having the motif TGT-N12-ACA are required for PpsR activity.

Identification and in vivo characterization of PpaA, a regulator of photosystem formation in Rhodobacter sphaeroides

“…Growth and genetic manipulations with strain PPA1 were conducted under anaerobic/dark conditions in presence 0?3 % (v/v) DMSO and 10 % (v/v) LB medium (Sambrook et al, 1989). P. denitrificans was grown in culture flasks as described previously (Gomelsky & Kaplan, 1995a). E. coli strains were grown in LB medium.…”

“…Pigments extracted from cell mass of equal protein content were assayed by UV-visible spectroscopy. Assays of b-galactosidase and catechol-2,3-dioxygenase activities in R. sphaeroides and P. denitrificans were performed as described previously (Gomelsky & Kaplan, 1995a;Dryden & Kaplan, 1990). b-Galactosidase activity in yeast was measured according to the protocol of the manufacturer of the MatchMaker kit (Stratagene).…”

“…Plasmid mobilization into R. sphaeroides and P. denitrificans was carried out from E. coli S17-1 as described previously (Gomelsky & Kaplan, 1995a) Construction of the PPA1 mutant. A deletion/substitution mutation in ppaA from R. sphaeroides 2.4.1 was constructed by replacing the internal NcoI fragment with an VKm r cartridge from pUI1637 (Gomelsky & Kaplan, 1995b) to generate plasmid p714BgHDNc : : Km (see Fig.…”

“…PpsR binds to the target sequences, TGTN 12 ACA (where N is a nucleotide), located upstream of puc and several crt and bch operons (Gomelsky & Kaplan, 1995a;Gomelsky et al, 2000). The DNA binding activity of PpsR is regulated in part through oxidation/ reduction of the thiol groups of its cysteine residues (Masuda et al, 2002;Masuda & Bauer, 2002) and in part through the anti-repressor AppA (Gomelsky & Kaplan, 1995c, 1997Braatsch et al, 2002;Masuda & Bauer, 2002).…”

“…Here we describe the characterization of the second gene identified in this screen. In our preliminary reports this gene was designated ppa for photopigment and puc activation (Gomelsky & Kaplan, 1994, 1995aHorne et al, 1997;Zelistra-Ryalls et al, 1998). It will be further referred to as ppaA.…”