Influence of light on accumulation of photosynthesis-specific transcripts in the cyanobacterium Synechocystis 6803

Abstract

Transcript accumulation for the psbA, psbD, psbD-C, rbcL-S and rrn genes in Synechocystis 6803 was followed under different light conditions. psbA, psbD, psbD-C and rbcL-S transcripts required light to accumulate and the relative abundance of these transcripts differed between high and low light conditions. Under high light conditions, steady-state levels of psbA, psbD and psbD-C transcripts were higher while levels of rbcL-S transcripts were lower than under low light conditions. rrn transcripts accumulated in the dark and the transcript levels were the same under illuminated conditions. Analyses of constructed Synechocystis 6803 mutants showed that both psbA-2 and psbA-3 could produce high levels of transcripts under illuminated conditions. No psbA-1 transcripts were detected.

Activation of the silent psbA1 gene in the cyanobacterium Synechocystis sp strain 6803 produces a novel and functional D1 protein.

“…Expression analyses have led us to conclude Jansson, 1989,1991;Mohamed et al, 1993) that the -35 and -10 motifs of psbA2 constitute a strong light-inducible promoter in Synechocystis sp 6803. No expression of thepsbA7 gene has been detected (Mohamed and Jansson, 1989), and alignment of the upstream regions of-the three psbA genes (Figure 2) has shown that the two putative psbA 7 promoters (Osiewacz and Mclntosh, 1987;Mohamed et al, 1993;Nixon and Jansson, 1996) differ significantly from the psbA2 and psbA3 promoters, particularly in the -35 element, which is identical in psbA2 and psbA3.…”

“…Because psbA2 is highly expressed under normal growth conditions (Mohamed and Jansson, 1989), we first tried to activate the psbAl gene by engineering -35 and -10 promoter elements identical in The psbA7 sequence is from Osiewacz and Mclntosh (1987), the psbA2 sequence is from Mohamed et al (1993), and the psbA3 sequence is from Metz et al (1990) and Mohamed et al (1993). Distances are given relative to the ATG start codon (italics).…”

“…RNA gel blot analyses using psbA1-and psb/42/3-specific probes ( Figure 5) confirmed that the psbA1 transcript is specific for the A1 -K mutant and that this strain contains no other full-length psbA transcripts. The short psbA fragment in A1-K that hybridized with the psbA2/3 probe corresponds to a truncated psbA2 transcript produced by the inactivated psbA2 gene (Mohamed and Jansson, 1989 1993). The psbA1-K gene was amplified by polymerase chain reaction (PCR) from A1-K cultures at three independent times and sequenced over the entire coding region and the 250-nucleotide flanking 5' end.…”

“…The psbAP and psbA3 coding regions share 99% nucleotide identity, and they encode an identical D1 protein (Ravnikar et al, 1989;Metz et al, 1990). 60th genes are expressed in a light-regulated manner (Mohamed and Jansson, 1989, with psbAP accounting for >90% of the produced psbA transcripts (Mohamed et al, 1993).…”

Expression of holo-proteorhodopsin in Synechocystis sp. PCC 6803

“…MED134 (6). The drop in PR content during the stationary phase may be in part due to the promoter we selected, because it is known that psbA2 expression and transcript stability are light-intensity dependent (68)(69)(70)(71)(72)(73), and so is heterologous expression driven by this promoter (74,75). It is worth noting that several of the recently discovered proteorhodopsins in 'chemotrophic', often psychrophilic, bacteria only contribute detectably to growth rate or cell yield when the cells are stressed and/or in stationary phase (6,(14)(15)(16)(18)(19)(20).…”