• Title, Summary, Keyword: Synechocystis PCC 6803

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Heterologous Expression and Characterization of Glycogen Branching Enzyme from Synechocystis sp. PCC6803

  • Lee, Byung-Hoo;Yoo, Young-Hee;Ryu, Je-Hoon;Kim, Tae-Jip;Yoo, Sang-Ho
    • Journal of Microbiology and Biotechnology
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    • v.18 no.8
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    • pp.1386-1392
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    • 2008
  • A gene (sll0158) putatively encoding a glycogen branching enzyme (GBE, E.C. 2.4.1.18) was cloned from Synechocystis sp. PCC6803, and the recombinant protein expressed and characterized. The PCR-amplified putative GBE gene was ligated into a pET-21a plasmid vector harboring a T7 promoter, and the recombinant DNA transformed into a host cell, E. coli BL21(DE3). The IPTG-induced enzymes were then extracted and purified using Ni-NTA affinity chromatography. The putative GBE gene was found to be composed of 2,310 nucleotides and encoded 770 amino acids, corresponding to approx. 90.7 kDa, as confirmed by SDS-PAGE and MALDI-TOF-MS analyses. The optimal conditions for GBE activity were investigated by measuring the absorbance change in iodine affinity, and shown to be pH 8.0 and $30^{\circ}C$ in a 50 mM glycine-NaOH buffer. The action pattern of the GBE on amylose, an $\alpha$-(1,4)-linked linear glucan, was analyzed using high-performance anion-exchange chromatography (HPAEC) after isoamylolysis. As a result, the GBE displayed $\alpha$-glucosyl transferring activity by cleaving the $\alpha$-(1,4)-linkages and transferring the cleaved maltoglycosyl moiety to form new $\alpha$-(1,6)-branch linkages. A time-course study of the GBE reaction was carried out with biosynthetic amylose (BSAM; $M_p{\cong}$8,000), and the changes in the branch-chain length distribution were evaluated. When increasing the reaction time up to 48 h, the weight- and number-average DP ($DP_w$ and $DP_n$) decreased from 19.6 to 8.7 and from 17.6 to 7.8, respectively. The molecular size ($M_p$, peak $M_w{\cong}2.45-2.75{\times}10^5$) of the GBE-reacted product from BSAM reached the size of amylose (AM) in botanical starch, yet the product was highly soluble and stable in water, unlike AM molecules. Thus, GBE-generated products can provide new food and non-food applications, owing to their unique physical properties.

Characterization of the Nickel Resistance Gene from Legionella pneumophila: Attenuation of Nickel Resistance by ppk (polyphosphate kinase) Disruption in Escherichia coli

  • Hahm, Dae-Hyun;Yeon, Mi-Jung;Ko, Whae-Min;Lee, Eun-Jooh;Lee, Hye-Jung;Shim, In-Sop;Kim, Hong-Yeoul
    • Journal of Microbiology and Biotechnology
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    • v.12 no.1
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    • pp.114-120
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    • 2002
  • A 1,989-bp genomic region encoding nickel resistance genes was isolated from Legionella pneumophila, a pathogen for legionellosis. From a sequencing and computer analysis, the region was found to harbor two structural genes, a nreB-like protein gene (1,149 bp) and a nreA-like protein gene (270 bp), in a row. Both genes exhibited a significant degree of similarity to the corresponding genes from Synechocystis sp. PCC6803 ($54\%$ amino acid sequence identity) and Achromobacter xylosoxidans 31A ($76\%$). The gene was successfully expressed in E. coli MG1655 and conferred a nickel resistance of up to 5 mM in an LB medium and 3 mM in a TMS medium including gluconate as the sole carbon source. E. coli harboring the nickel resistance gene also exhibited a substantial resistance to cobalt, yet no resistance to cadmium or zinc. Since the extracellular concentration of nickel remained constant during the whole period of cultivation, it was confirmed that the nickel resistance was provided by an efflux system like the $Ni^2+$permease (nrsD) of Synechocystis sp. strain PCC6803. Since polyphosphate (poly-P) is known as a global regulator for gene expression as well as a potential virulence factor in E. coli, the nickel resistance of a ppk mutant of E. coli MG 1655 harboring the nickel resistance gene from L. pneumophila was compared with that of its parental strain. The nickel resistance was significantly attenuated by ppk inactivation, which was more pronounced in an LB medium than in a TMS medium.

Cyanobacterial bioreporters for detection of heavy metals, herbicide, and antibiotics (중금속, 제초제 및 항생제 검출용 남세균 유래 바이오 리포터)

  • Kim, Soo-Youn;Jeong, Won-Joong;Suh, Kye-Hong;Liu, Jang-Ryol;Park, Youn-Il
    • Journal of Plant Biotechnology
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    • v.35 no.2
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    • pp.141-145
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    • 2008
  • In this study, glucose-inducible intergenic sequences were used to generate bioreporters of the cyanobacterium Synechocystis sp. PCC 6803 that could monitor environmental pollutants. Luciferase genes LuxAB from the marine bacterium Vibrio fischeri under the control of glucose-inducible intergenic seqeucens of eight genes (atpI, ndbA, ctaD1, tkt, pgi, pdh, ppc, and cydA) were successfully expressed in the cyano-bacterial transformants, showing 5-25 fold increases in biolumeniscence upon exposure to glucose. In addition, glucose-inducible cyanobacterial bioreporters were very sensitive to various chemicals such as heavy metals ($Hg^{2+}$, $Cu^{2+}$, $Zn^{2+}$), electron transport inhibitors (DCMU, DBMIB, $CN^-$), and antibiotics (chloramphenicol and rifampicin). These glucose-inducible cyanobacterial bioreporters would be useful to develop biosensors for rapid screening of environmental samples.

형질전환 벼에서 Cyanobacterial Sucrose-Phosphate Synthase 유전자의 발현

  • Sang-Kyu Lee;Soo-Jung Lee;Na-Yeon Ryoo;Jang-Wook Lee;Seok-Yoon Yoon;Woon-Chul Shin;Se-Ho Ko;Deok Chun Yang;Youn-Hyung Lee
    • Proceedings of the Plant Resources Society of Korea Conference
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    • pp.126-126
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    • 2003
  • Sucrose-phosphate synthase (SPS) is a key regulatory enzyme in sucrose synthesis. To investigate the role of SPS in carbon partitioning, we produced transgenic rice plants overexpressing a cyanobacterial SPS from Synechocystis sp. PCC 6803. The gene was expressed under the control of the maize Ubil promoter in transgenic plants. Southern and Northern blot analyses confirmed the integration and the expression of the transgene in four transgenic rice lines. All of the four transgenic! lines analyzed showed abnormal vegetative and reproductive developments. Analysis of SPS activities and primary metabolites in the transgenic rice plants will be presented.

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A NOVEL PHOTOHETEROTROPHIC MUTANT FOR psaB GENE OF Synechocystis sp. PCC 6803 GENERATED FROM TARGETED MUTAGENESIS

  • Kim, Soohyun;Kim, Seung-Il;Choi, Jong-Soon;Chung, Young-Ho;Chun, Soon-Bai;Park, Young-Mok
    • Journal of Photoscience
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    • v.3 no.1
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    • pp.23-28
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    • 1996
  • To investigate the structure and function of photosystem I, cartridge mutagenesis technique was used to inactivate the psaB gene of photosystem I. From the screen, many strains which have potential defects in photosystem I were generated. Biochemical analysis revealed that B2, one of the mutant, had a reduced amount of chlorophyll. Electron transfer activitx from photosystem II to photosystem I as oxygen uptake was the rate of 64 % of wild type. Also B2 showed a decreased photosystem I activity when measured by 77 K fluorescence emission spectrum. Particularly, immunodetection analysis showed that the B2 had reduced amount of PsaA/PsaB, but a normal range of PsaC and PsaD. Here we present a photoheterotrophic mutant for psaB gene as a unique model strain for future study of structural/functional relationship and biogenesis of photosystem I.

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