Genes for the alpha and beta subunits of phycocyanin.

Lorimier, Robert de; Bryant, Donald A.; Porter, Ronald D.; Liu, W Y; Jay, Ernest; Stevens, S. E.

doi:10.1073/pnas.81.24.7946

Cited by 125 publications

(53 citation statements)

References 31 publications

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“…To explore the reasons that the lrtA transcript is more stable in the dark, differences in RNase activity between dark-adapted and illuminated cells were measured by the degradation of in vitro-labeled RNA visualized on acrylamide gels. Several RNAs were used to monitor RNase activity, including petCA (Brand et al, 1992), cpcBAC (de Lorimier et al, 1984), ndhB (M. Varughese and W.R. Widger, unpublished data), both sense and antisense lrtA fragments, and the fulllength sense lrtA message. Figure 4 shows the time course for RNA digestion by cell extracts obtained from light-and dark-adapted cells.…”

Section: Rnase Activities Of Cell Extracts From Dark-or Lightadapted mentioning

confidence: 99%

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Transcriptional and Posttranscriptional Control of mRNA fromlrtA, a Light-Repressed Transcript inSynechococcus sp. PCC 70021

Samartzidou

Widger

1998

Plant Physiology

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Transcription regulation and transcript stability of a lightrepressed 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 M 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 untranslated region, which is also present in the 5 untranslated region of lrtA from a different cyanobacterium, Synechocystis sp. PCC 6803. Evidence suggests that lrtA transcript stability is not the result of differences in ribonuclease activity from dark to light. Small amounts of lrtA transcript were detected in illuminated cells upon the addition of 25 g mL ؊1 chloramphenicol. The addition of chloramphenicol to dark-adapted cells before illumination allowed detection of the lrtA transcript for longer times in the light relative to controls without chloramphenicol. These results suggest that lrtA mRNA processing in the light is different from that in the dark and that protein synthesis is required for light repression of the lrtA transcript.

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Section: Rnase Activities Of Cell Extracts From Dark-or Lightadapted mentioning

confidence: 99%

“…Templates for the probes included the 0.89-kb BamHI fragment from lrtA (Fig. 1), the 1.6-kb BamHI fragment from petCA (Brand et al, 1992), and the 880-bp XhoI-BamHI fragment from cpcBAC (de Lorimier et al, 1984). The full-length sense lrtA probe was synthesized using E. coli RNA polymerase.…”

Section: Rnase Assaysmentioning

confidence: 99%

Transcriptional and Posttranscriptional Control of mRNA fromlrtA, a Light-Repressed Transcript inSynechococcus sp. PCC 70021

Samartzidou

Widger

1998

Plant Physiology

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“…Total genomic DNA Synechococcus sp. strain PCC 7002 was prepared as previously described (9). For the construction of the Agtwes library of Synechococcus sp.…”

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confidence: 99%

“…DNA ligations, plasmid transformations, nick translations, and Southern (43) and plaque hybridizations were done by using standard procedures (27). All hybridizations included at least a 6-h prehybridization in 6x SET (lx SET is 150 mM NaCl, 30 (4,9).…”

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confidence: 99%

Molecular cloning and characterization of the recA gene from the cyanobacterium Synechococcus sp. strain PCC 7002

Murphy¹,

Bryant²,

Porter³

et al. 1987

J Bacteriol

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The recA gene of Synechococcus sp. strain PCC 7002 was detected and cloned from a lambda gtwes genomic library by heterologous hybridization by using a gene-internal fragment of the Escherichia coli recA gene as the probe. The gene encodes a 38-kilodalton polypeptide which is antigenically related to the RecA protein of E. coli. The nucleotide sequence of a portion of the gene was determined. The translation of this region was 55% homologous to the E. coli protein; allowances for conservative amino acid replacements yield a homology value of about 74%. The cyanobacterial recA gene product was proficient in restoring homologous recombination and partial resistance to UV irradiation to recA mutants of E. coli. Heterologous hybridization experiments, in which the Synechococcus sp. strain PCC 7002 recA gene was used as the probe, indicate that a homologous gene is probably present in all cyanobacterial strains.

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“…The genes encoding the a and 13 subunits of PC (cpcA and cpcB, respectively) are linked in tandem with those encoding LR33 (cpcC) and LR9 (cpcD) (7)(8)(9)20) (Fig. 4).…”

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Regulation of Phycobilisome Structure and Gene Expression by Light Intensity

Lorimier

Smith²,

Stevens³

1992

Plant Physiol.

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The cyanobacterium Agmenellum quadruplicatum PR-6 (Synechococcus sp PCC 7002) was grown turbidostatically in white light at three levels of irradiance: 20, 200, and 1260 microeinsteins per square meter per second. Phycobilisomes were isolated from each culture and analyzed by absorbance, gel electrophoresis, and electron microscopy. The ratio of phycocyanin to allophycocyanin decreased 1.8-fold from the lowest to highest irradiance. This change was due entirely to an approximately 2.5-fold decrease in one structural unit of rod domains, the complex of phycocyanin, and a 33-kilodalton linker polypeptide (LR33). For a given irradiance, phycobilisomes from cells grown on ammonium as the nitrogen source had 10 to 20% more phycocyanin than those from nitrate cultures. Total RNA was isolated from all cultures and probed with gene fragments specific to phycocyanin and allophycocyanin subunits and LR33. The relative level of RNAs encoding phycocyanin and allophycocyanin was found to vary with light intensity in parallel with the phycobiliprotein ratio. Hence, the light-harvesting capacity of phycobilisomes is directly regulated by relative levels of phycobiliprotein mRNA. The LR33 transcript occurs as a 3' extension on about 10% of phycocyanin transcripts. The ratio of RNA encoding LR33 to that encoding phycocyanin did not vary with irradiance, although the protein ratio changed 1.7-to twofold between extremes. Based on these and other observations, we propose that the LR33 protein is constitutively synthesized at a rate higher than that required to complex with available phycocyanin.The cyanobacterium Agmenellum quadruplicatum (Synechococcus sp PCC 7002) was chosen for this study. The phycobilisomes of this organism are well described in terms ofoverall structure and the function ofindividual polypeptide components (reviewed in refs. 2 and 6). The major components of this complex are the pigmented proteins, PC' and AP. The former is localized in rod substructures, where it is bound to linker polypeptides called LRC29, LR33, and LR9. Rods are linked to a central core domain by LRC29. The core contains AP and its associated linker polypeptides.The genes encoding the a and 13 subunits of PC (cpcA and cpcB, respectively) are linked in tandem with those encoding LR33 (cpcC) and LR9 (cpcD) (7-9, 20) (Fig. 4). Genes encoding AP a and ,B subunits (apcA and apcB, respectively) and one linker polypeptide (LC8.5) are similarly clustered (4). Transcripts encoding these cpc and apc loci have been mapped (12). The major transcript of each locus encodes only the a and ,B subunits of the respective phycobiliproteins. Minor transcripts extend further in the 3' direction to encode linker polypeptides. Having this knowledge of phycobilisome structure and gene organization in A. quadruplicatum, we could readily investigate responses to changes in light intensity.In addition to irradiance, we simultaneously examined the effect of nitrogen source on phycobilisome structure. This is of interest because phycobiliproteins are strongly...

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Genes for the alpha and beta subunits of phycocyanin.

Cited by 125 publications

References 31 publications

Transcriptional and Posttranscriptional Control of mRNA fromlrtA, a Light-Repressed Transcript inSynechococcus sp. PCC 70021

Transcriptional and Posttranscriptional Control of mRNA fromlrtA, a Light-Repressed Transcript inSynechococcus sp. PCC 70021

Molecular cloning and characterization of the recA gene from the cyanobacterium Synechococcus sp. strain PCC 7002

Regulation of Phycobilisome Structure and Gene Expression by Light Intensity

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