The light-responsive promoter of cyanobacterial ORF76 gene overlaps with the htpG terminator (original) (raw)
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Archives of Microbiology, 1996
We designed a strategy to isolate and characterize response regulator genes from the cyanobacterium Synechococcus sp. strain PCC 7942 based on the premise that cyanobacterial response regulators would bear strong similarity to their counterparts from other eubacteria. Two response regulator genes, srrA and srrB, were isolated from Synechococcus and found to encode proteins similar to the OmpR subclass of response regulators. Disruption of either gene by insertional mutagenesis did not produce an obvious phenotype and did not affect the accumulation of psbAII mRNA under high-light conditions, indicating that these gene products are not involved in mediating the well characterized standard- to high-light transition response of photosystem II genes in this cyanobacterium. Analysis of the chromosomal region adjacent to srrA revealed the presence of another presumptive transcriptional activator gene. This gene, named lrrA, belongs to the lysR family. Attempts to disrupt lrrA or an adjacent ORF (orfG) were not successful, suggesting that these genes are important for the growth of Synechococcus.
Journal of Bacteriology, 2004
The high-light-inducible proteins (HLIPs) of cyanobacteria are polypeptides involved in protecting the cells from high-intensity light (HL). The hliA gene encoding the HLIP from Synechococcus elongatus strain PCC 7942 is expressed in response to HL or low-intensity blue or UV-A light. In this study, we explore via Northern analysis details of the transcriptional regulation and transcript stability of the hliA gene under various light conditions. Transcript levels of the hliA gene increased dramatically upon a shift to HL or UV-A light to similar levels, followed by a rapid decrease in UV-A light, but not in HL, consistent with blue/UV-A light involvement in early stages of HL-mediated expression. A 3-min pulse of low-intensity UV-A light was enough to trigger hliA mRNA accumulation, indicating that a blue/UV-A photoreceptor is involved in upregulation of the gene. Low-intensity red light was found to cause a slight, transient increase in transcript levels (raising the possibility of...
Plant physiology, 1998
Transcription regulation and transcript stability of a light-repressed transcript, lrtA, from the cyanobacterium Synechococcus sp. PCC 7002 were studied using ribonuclease protection assays. The transcript for lrtA was not detected in continuously illuminated cells, yet transcript levels increased when cells were placed in the dark. A lag of 20 to 30 min was seen in the accumulation of this transcript after the cells were placed in the dark. Transcript synthesis continued in the dark for 3 h and the transcript levels remained elevated for at least 7 h. The addition of 10 microM rifampicin to illuminated cells before dark adaptation inhibited the transcription of lrtA in the dark. Upon the addition of rifampicin to 3-h dark-adapted cells, lrtA transcript levels remained constant for 30 min and persisted for 3 h. A 3-h half-life was estimated in the dark, whereas a 4-min half-life was observed in the light. Extensive secondary structure was predicted for this transcript within the 5&#...
Molecular Microbiology, 1998
The Synechocystis PCC6803 secA gene was found to be essential for cell viability and to be transcriptionally controlled by the redox state of the cells. The basic promoter (BP, ¹71 to þ47 relative to the transcription start site) is controlled by three cis-acting elements, which together mediate the fourfold light induction of BP activity. The positively acting element (PE1, ¹361 to ¹71) upstream of BP exerts a twofold stimulation of BP; the negative element (NE, þ47 to þ104) downstream of BP decreases BP strength about sixfold. The PE2 element (þ104 to þ175) lying in the coding sequence overcomes NE-dependent downregulation of BP. BP harbours Escherichia coli 70 -like promoter elements ¹35 (5Ј-TTGAat-3Ј) and
Promoters of the Phycocyanin Gene Clusters of the Cyanobacterium Synechococcus sp. Strain PCC 7942
Plant and Cell Physiology, 1998
The cyanobacterium Synechococcus sp. strain PCC 7942 has duplicated phycocyanin subunit gene clusters cpcBlAl and cpcB2A2, which are identical to each other and to those of Synechococcus sp. strain PCC 6301 (Anacystis nidulans). Nucleotide sequences of the 428 and 286 bases of the 5' non-coding regions of the cpcBlAl and cpcB2A2 clusters, respectively, of strain PCC 7942 were identical to those of strain PCC 6301. As in strain PCC 6301, cpcBlAl yielded two major transcripts of 1.4 and 1.3 kb and cpcB2A2 yielded a single transcript of 1.3 kb in strain PCC 7942. Thus, the structure and expression of cpcBA gene clusters in the two strains are essentially the same. Using bacterial luciferase encoded by luxAB as a reporter, cpcBlAl was shown to have two promoters corresponding to the two major transcripts. Luminescence from the Synechococcus reporter strains carrying the fusions of the cpcBA promoters to luxAB showed circadian oscillation. Similar to the promoter of psbAl encoding the Dl protein of PSH, the two cpcBlAl promoters and the cpcB2A2 promoter showed the peak of activity at the end of the subjective day and the trough at the end of the subjective night.
Gene, 1993
The regulation of the light-harvesting antennae, the phycobil~some (Pbs), and the cpcBIAI-epcH-cpc-cpc-cpcD operon encoding the structural proteins of the Pbs rod, was studied in the cyanobact~r~um, ~~~~e~~ococc~s sp. PCC 6301, when grown at different light intensities (Ii). Pbs were purified and their linker protein (LP) profiles analyzed on SDS-polyacrylamide gels. At increasing Ii, the amount of the distal 30-kDa LP decreased prior to any change in the amount of the proximal 33-kDa LP, indicating a sequential increase in the Pbs rod length. While the amount of LP in the rod decreased with increasing ii, the levels of the LP mRNAs increased, Post-transcriptional regulation of the expression of the polycistronic cpcBlAI-cpcH-cpcf-cpcD mRNA was inferred from these observations. The half-life of the mRNAs studied was typically found to be 7 min with four exceptions: (I and 2) the half-lives for the 3.4-and 3.7-kb polycistroni~ LP mRNAs were 16 and 1 min at the low (lli) and high li (hli), respectively; (3) the half-life of the 1.4-kb cpcBlAi mRNA was 2 min at hi; and (4) the 1.3-kb cpcBfAI transcript had a half-life of 10 min at lli. At hli, it was found that the 1.3kb cpd?ZAl transcript did not start to disappear until the amount of the 1.4-kb cpcBIAl transcript had reached the level equal to that of the 1.3-kb mRNA, implying that the 1.4-kb transcript might be processed to the 1.3-kb form. The phycobilisome (Pbs), which functions as the lightharvesting antennae in cyanobacteria, is a water-soluble, macromolecular complex composed of phycobjliprot~ins and linker proteins (LP) (Glazer, 1981; 1983; 1984). The phycobiliproteins have chromophores, bilins, covale~tly attached to Cys residues in the aa backbone and are directly involved in the light-harvesting and transport of
A Novel Expression Vector for the Cyanobacterium, Synechococcus PCC 6301
DNA Research, 1994
A cyanobacterial expression vector was constructed using ribulose-l,5-bisphosphate carboxylase/oxygenase (RuBisCO) promoter and terminator sequences derived from Synechococcus PCC 6301. The recombinant plasmid, designated pARUB19, has an ampicillin-resistant (Ap R) gene as a selectable marker and four unique restriction sites to allow the insertion of foreign genes. Using this vector, the luciferase gene from the firefly, Photinus pyralis, was introduced into Synechococcus PCC 6301 cells. The luciferase expression vector could be maintained stably in the host cells. Light production of luciferin/luciferase was detected in the transformants. Luciferase amounted to 1.2% of the total soluble protein. This plasmid may facilitate higher levels of foreign gene expression in Synechococcus PCC 6301.
A promoter-probe vector-host system for the cyanobacterium, Synechocystis PCC6803
Gene, 1989
A vector-host system for testing promoters in the cyanobacterium Synechocystis PCC6803 has been constructed. It relies on a small Escherichiu coli promoter-probe plasmid, pFF11, which has four unique restriction sites in a polylinker upstream from the cat reporter gene. This plasmid is able to obtain a cyanobacterial origin of replication by homologous recombination with the resident plasmid of the recipient host, generating a new E. coli-Synechocystzk PCC6803 shuttle vector. This plasmid does not confer any detectable chloramphenicol acetyl transferase activity to this cyanobacterium in the absence of a promoter insert. Several heterologous promoters were tested in Synechocystis PCC6803 using this system. Results obtained with the ApR promoter and the repressor-encoding ~1857 gene demonstrate that these elements can be used for high-level and tightly regulated gene expression in Synechocystis PCC6803.