• 한국약용작물학회지
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• 제13권5호
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• pp.276-283
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• 2005

Ascorbic acid is a great antioxidant and helps protect the body against pollutants. GDP-mannose pyrophosphorylase (GMPase) is a key enzyme in manufacturing GDP-mannose, a glycosyl donor for ascorbate and cell wall biosynthesis as well as for protein glycosylation. In this study, we described molecular cloning of a full-length cDNA from Potato (Solanum tuberosum L. cv. Jasim), using tuber. The cDNA isolated encoded a GDP-mannose pyrophosphrylase. The nucleotide sequence of pGMPC showed about 95%, 89% and 80% homology with S. tuberosum (AF022716), N. tabacum (AB066279) and A. thaliana (AF076484) cDNAs clone known as GMPase, respectively. We detected the expression of GMPase using RT-PCR. The highest expression of GMPase was found in stems, and the largest amount of ascorbic acid was also presented in stems. In contrast, the leaf showed minimal level of GMPase transcript and ascorbic acid content. We propose that GMPase expression patterns were similar to the changes of ascorbic acid content in the leaves treated with diverse stresses.

• BMB Reports
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• 제42권8호
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• pp.523-528
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• 2009

Phosphomannose isomerase (PMI) catalyzes the interconversion of fructose-6-phosphate and mannose-6-phosphate in the extracellular polysaccharide (EPS) synthesis pathway. The gene encoding PMI in Sphingomonas chungbukensis DJ77 was cloned and expressed in E. coli. The pmi gene is 1,410 nucleotides long and the deduced amino acid sequence shares high homology with other bifunctional proteins that possess both PMI and GDP-mannose pyrophosphorylase (GMP) activities. The sequence analysis of PMI revealed two domains with three conserved motifs: a GMP domain at the N-terminus and a PMI domain at the C-terminus. Enzyme assays using the PMI protein confirmed its bifunctional activity. Both activities required divalent metal ions such as $Co^{2+}$, $Ca^{2+}$, $Mg^{2+}$, $Ni^{2+}$ or $Zn^{2+}$. Of these ions, $Co^{2+}$ was found to be the most effective activator of PMI. GDP-D-mannose was found to inhibit the PMI activity, suggesting feedback regulation of this pathway.

• Journal of Microbiology and Biotechnology
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• 제16권6호
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• pp.961-964
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• 2006

GDP-mannosyltransferase (GMT) is an enzyme responsible for the addition of a mannose to glucose ($\alpha$[1$\rightarrow$3]) during biosynthesis of the water-soluble branched polysaccharide acetan in Acefobacter species. In an effort to obtain a cellulose-overproducing bacterium, a mutant defective in GMT of Acetobacter xylinum KCCM 10100 was constructed by single crossover homologous recombination using part of the aceA gene encoding GMT amplified by polymerase chain reaction. The GMT-disrupted mutant produced 23% more cellulose, but 16% less water-soluble polysaccharide than those of the wild-type strain. Analysis of the sugar composition by gel permeation chromatography revealed that water-soluble polysaccharides produced by the GMT-defective mutant contained no mannose molecule.

• 한국생물공학회:학술대회논문집
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• 한국생물공학회 2003년도 생물공학의 동향(XIII)
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• pp.509-510
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• 2003

• 한국생물공학회:학술대회논문집
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• 한국생물공학회 2003년도 생물공학의 동향(XII)
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• pp.588-588
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• 2003

• Journal of Microbiology and Biotechnology
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• 제28권8호
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• pp.1293-1298
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• 2018

Phosphomannomutase (ManB) converts mannose-6-phosphate (M-6-P) to mannose-1-phosphate (M-1-P), which is a key metabolic precursor for the production of GDP-D-mannose used for production of glycoconjugates and post-translational modification of proteins. The aim of this study was to express the manB gene from Escherichia coli in Lactococcus lactis subsp. cremoris NZ9000 and to characterize the encoded enzyme. The manB gene from E. coli K12, of 1,371 bp and encoding 457 amino acids (52 kDa), was cloned and overexpressed in L. lactis NZ9000 using the nisin-controlled expression system. The enzyme was purified by Ni-NTA column chromatography and exhibited a specific activity of 5.34 units/mg, significantly higher than that of other previously reported ManB enzymes. The pH and temperature optima were 8.0 and $50^{\circ}C$, respectively. Interestingly, the ManB used in this study had two substrate specificity for both mannose-1-phosphate and glucose-1-phosphate, and the specific activity for glucose-1-phosphate was 3.76 units/mg showing 70% relative activity to that of mannose-1-phosphate. This is the first study on heterologous expression and characterization of ManB in lactic acid bacteria. The ManB expression system constructed in this study canbe used to synthesize rare sugars or glycoconjugates.

• 한국미생물·생명공학회지
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• 제33권2호
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• pp.84-89
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• 2005

Phosphomannomutase는 진핵 생물과 원핵 생물에 있어서 중요한 효소로, ${\alpha}$-D-mannose 6-phosphate를 ${\alpha}$-D-mannose 1-phosphate로 전환시켜 GDP-mannose를 생산한다. 이 기질은 여러 대사 경로에서 중요하게 작용하는 mannosyl기를 제공하도록 돕는다. 본 논문에서는 Sphingomonas chungbukensis DJ77에서 phosphomannomutase를 암호화하는 유전자를 유전체 library로부터 동정하고 이를 pmmC로 명명하였으며, 이를 발현 vector에 클로닝하고 염기서열을 분석하였다. 유전자 pmmC는 ATG를 개시 코돈으로 사용하고, TAG를 종결 코돈으로 사용하는 750 bp의 open reading frame임을 확인하였고, 이 ORF의 5 bp앞쪽으로 리보좀 결합 부위가 존재한다. 이 ORF로부터 유추되는 아미노산은 249개이며, 단백질 분자량은 약 27.4 kDa이다. 이 유전자를 구성하는 아미노산 서열은 NCBI의 conserved domain search를 통한 분석으로 eukaryotic phosphomannomutase와 약 $86.9\%$ 유사성이 있음을 나타냈고, 기질에 대한 활성을 측정한 결과 pmmC 유전자가 암호화하는 단백질이 phosphomannomutase임을 확인할 수 있었다.

• Parasites, Hosts and Diseases
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• 제44권1호
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• pp.15-20
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• 2006

Free-living amoebae of the genus Acanthamoeba are causative agents of granulomatous amebic encephalitis and amebic keratitis. Because the virulence of Acanthamoeba culbertsoni cultured in the laboratory is restored by consecutive brain passages, we examined the genes induced in mouse brain-passaged A. culbertsoni by differential display reverse transcriptase polymerase chain reaction (DDRT-PCR). Enhanced A. culbertsoni virulence was observed during the second mouse brain passage, i.e., infected mouse mortality increased from $5\%\;to\;70\%.$ Ten cDNAs induced during mouse brain passage were identified by DDRT-PCR and this was confirmed by northern blot analysis. BlastX searches of these cDNAs indicated the upregulations of genes encoding predictive NADH-dehydrogenase, proteasomal ATPase, and GDP-mannose pyrophosphorylase B, which have previously been reported to be associated with A. culbertsoni virulence factors.

• Journal of Microbiology
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• 제45권1호
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• pp.69-74
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• 2007

Escherichia coli is a clonal species, and occurs as both commensal and pathogenic strains, which are normally classified on the basis of their O, H, and K antigens. The O-antigen (O-specific polysaccharide), which consists of a series of oligosaccharide (O-unit) repeats, contributes major antigenic variability to the cell surface. The O-antigen gene cluster of E. coli O66 was sequenced in this study. The genes putatively responsible for the biosynthesis of dTDP-6-deoxy-L-talose and GDP-mannose, as well as those responsible for the transfer of sugars and for O-unit processing were identified based on their homology. The function of the wzy gene was confirmed by the results of a mutation test. Genes specific for E. coli O66 were identified via PCR screening against representatives of 186 E. coli and Shigella O type strains. The comparison of intergenic sequences located between galF and the O-antigen gene cluster in a range of E. coli and Shigella showed that this region may perform an important function in the homologous recombination of the O-antigen gene clusters.

• Journal of Microbiology and Biotechnology
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• 제22권10호
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• pp.1324-1329
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• 2012

Phosphomannomutase (ManB) is involved in the biosynthesis of GDP-mannose, which is vital for numerous processes such as synthesis of carbohydrates, production of alginates and ascorbic acid, and post-translational modification of proteins. Here, we discovered that a deletion mutant of manB (BG101) in Streptomyces coelicolor (S. coelicolor) showed higher sensitivity to bacteriostatic chloramphenicol (CM) than the wild-type strain (M145), along with decreased production of CM metabolites. Deletion of manB also decreased the mRNA expression level of drug efflux pumps (i.e., cmlR1 and cmlR2) in S. coelicolor, resulting in increased sensitivity to CM. This is the first report on changes in antibiotic sensitivity to CM by deletion of one glycolysis-related enzyme in S. coelicolor, and the results suggest different approaches for studying the antibiotic-resistant mechanism and its regulation.