Restriction barrier composed of an extracellular nuclease and restriction endonuclease in the unicellular cyanobacterium<i>Microcystis</i>sp.

Takahashi, Ikuo; Hayano, Daisuke; Asayama, Munehiko; Futagami, Masahiro; Watahiki, Masanori; Shirai, Makoto

doi:10.1111/j.1574-6968.1996.tb08564.x

Cited by 23 publications

(2 citation statements)

References 11 publications

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“…Members of the genus Microcystis (Synechocystis) are cyanobacteria (blue-green algae) which can perform oxygenic photosynthesis involving two photosystems, PS I and PS II, as in higher plants. One such member, the unicellular, colonyforming Microcystis aeruginosa K-81 (hereafter referred to as K-81) strain was isolated (1) and characterized with regard to its biological and genetic properties (2,3). The K-81 strain possesses multiple psbA genes in its chromosome.…”

Section: Introductionmentioning

confidence: 99%

An AU-box motif upstream of the SD sequence of light-dependent psbA transcripts confers mRNA instability in darkness in cyanobacteria

Agrawal

Kato

Asayama

et al. 2001

Nucleic Acids Research

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The psbA2 gene of a unicellular cyanobacterium, Microcystis aeruginosa K-81, encodes a D1 protein homolog in the reaction center of photosynthetic Photosystem II. The expression of the psbA2 transcript has been shown to be light-dependent as assessed under light and dark (12/12 h) cycling conditions. We aligned the 5'-untranslated leader regions (UTRs) of psbAs from different photosynthetic organisms and identified a conserved sequence, UAAAUAAA or the 'AU-box', just upstream of the SD sequences. To clarify the role of 5'-upstream cis-elements containing the AU-box for light-dependent expression of psbA2, a series of deletion and point mutations in the region were introduced into the genome of heterologous cyanobacterium Synechococcus sp. strain PCC 7942, and psbA2 expression was examined. A clear pattern of light-dependent expression was observed in recombinant cyanobacteria carrying the K-81 psbA2 -38/+36 region (which includes the minimal promoter element and a light-dependent cis-element with the AU-box), +1 indicating the transcription start site. A constitutive pattern of expression, in which the transcripts remained almost stable under dark conditions, was obtained in cells harboring the -38/+14 region (the minimal element), indicating that the +14/+36 region with the AU-box is important for the observed light-dependent expression. Point mutations analyses within the AU-box also revealed that changes in number, direction and identity (as assayed by adenine/uridine nucleotide substitutions) influenced the light-dependent pattern of expression. The level of psbA2 transcripts increased markedly in CG- or deletion-box mutants in the dark, strongly indicating that the AU- (AT-) box acts as a negative cis-element. Furthermore, characterization of transcript accumulation in cells treated with rifampicin suggests that psbA2 5'-mRNA is unstable in the dark, supporting the view that the light-dependent expression is controlled at the post-transcriptional level. We discuss various mechanisms that may lead to altered mRNA stability such as the binding of factor(s) or ribosomes to the 5'-UTR and possible roles of the AU-box motif and the SD sequence.

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Section: Introductionmentioning

confidence: 99%

An AU-box motif upstream of the SD sequence of light-dependent psbA transcripts confers mRNA instability in darkness in cyanobacteria

Agrawal

Kato

Asayama

et al. 2001

Nucleic Acids Research

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“…In cyanobacteria, possible transformation methods include natural transfer, the electroporation of extraneous DNA, and the transfer of foreign DNA by bacterial conjugation (Golden et al 1987; Heidorn et al 2011; Kuhlemeier and van Arkel 1987; Marraccini et al 1993; Simon 1984; Thiel 1994; Thiel and Wolk 1987). The efficiency of the transformation depends on the donor DNA form and on the competency of the cyanobacterial recipient cells and, as well as in conjugation, on the restriction–modification barriers of the cells (Takahashi et al 1996). Furthermore, the transferred DNA is classified by fate.…”

Section: Introductionmentioning

confidence: 99%

Overproduction and easy recovery of target gene products from cyanobacteria, photosynthesizing microorganisms

Asayama

2012

Appl Microbiol Biotechnol

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New cyanobacterial expression vectors, possessing an origin of replication that functions in a broad range of Gram-negative bacteria, were constructed. To inspect the shuttle vectors, the gene gfp was cloned downstream from the expression control element (ECE) originating from the regulatory region of the Microcystis aeruginosa gene psbA2 (for photosystem II D1 protein), and the vectors were introduced into three kinds of cyanobacteria ( Synechocystis sp. PCC 6803, Synechococcus elongatus PCC 7942, and Limnothrix / Pseudanabaena sp. ABRG5-3) by conjugation. Multiple copy numbers of the expression vectors (in the range of 14–25 copies per cell) and a high expression of green fluorescent protein (GFP) at the RNA/protein level were observed in the cyanobacterial transconjugants. Importantly, GFP was observed in a supernatant from the autolysed transconjugants of ABRG5-3 and easily collected from the supernatant without centrifugation and/or further cell lysis. These results indicate the vectors together with the recombinant cells to be useful for overproducing and recovering target gene products from cyanobacteria. Electronic supplementary material The online version of this article (doi:10.1007/s00253-012-3989-0) contains supplementary material, which is available to authorized users.

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Evidence for Recombination in the Microcystin Synthetase (mcy) Genes ofToxic Cyanobacteria Microcystis spp

2004

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Recombination has been suggested to be an important factor for the genetic variation of bacterial genes, but few studies have dealt with intragenic recombination between the same or closely related species of cyanobacteria. Here we provide strong evidence for recombination in the microcystin synthetase (mcy) gene cluster of the toxic cyanobacteria Microcystis spp. This gene cluster contains 10 genes (mcyA to J) that encode a mixed polyketide synthase (PKS)/nonribosomal peptide synthetase (NRPS) complex. mcy gene sequences were determined for four selected regions (within mcyA, D, G, and J) within the mcy gene cluster from 1 Canadian and 10 Asian toxic Microcystis and compared with previously published mcy sequences. Split decomposition analysis indicated a reticulate phylogeny of mcyA, and several potential recombination tracts of mcyA were identified by the RDP analysis and a runs test implemented in GENECONV. In contrast, no recombination was detected in the mcyD, G, and J sequences. However, discrepancies among the four mcy gene genealogies were evident from the results of independent split decomposition analyses, which were further supported by incongruence length difference (ILD) tests. Taken together, these findings suggest that both intragenic and intergenic recombination within the mcy gene cluster contributes to the genetic diversity of the mcy genes of Microcystis spp.

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Restriction barrier composed of an extracellular nuclease and restriction endonuclease in the unicellular cyanobacteriumMicrocystissp.

Cited by 23 publications

References 11 publications

An AU-box motif upstream of the SD sequence of light-dependent psbA transcripts confers mRNA instability in darkness in cyanobacteria

An AU-box motif upstream of the SD sequence of light-dependent psbA transcripts confers mRNA instability in darkness in cyanobacteria

Overproduction and easy recovery of target gene products from cyanobacteria, photosynthesizing microorganisms

Evidence for Recombination in the Microcystin Synthetase (mcy) Genes ofToxic Cyanobacteria Microcystis spp

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