• Journal of Microbiology
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• 제45권6호
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• pp.583-589
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• 2007

The promoter region of pyrC (dihydroorotase) gene of Escherichia coli was shown to have Fur protein binding properties by gel retardation assay. In vivo regulation of the pyrC expression was studied by measuring dihydroorotase activity and ${\beta}$-galactosidase level in the $fur^+$ and $fur^-$ genetic background. The expression of chromosomal dihydroorotase activity and ${\beta}$-galactosidase activity of pyrC-lacZ fusion plasmid was repressed to about 30% and 17%, respectively in the $fur^+$ strain compared to those in the $fur^-$ strain. Divalent ions such as $Fe^{2+}$ and $Zn^{2+}$ were not required for the repression. PyrC expression was also reduced to one half by 1 mM uracil. The effect of uracil was independent on the fur gene.

• Biotechnology and Bioprocess Engineering:BBE
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• 제7권3호
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• pp.155-162
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• 2002

The cyclic amidohydrolase family enzymes, which include allantoinase, dihydroorotase, dihydropyrimidinase and (phenyl)hydantoinase, are metal-dependent hydrolases and play a crucial role in the metabolism of purine and pyrimidine in vivo. Each enzyme has been independently characterized, and thus well documented, but studies on the higher structural traits shared by members of this enzyme family are rare due to the lack of comparative study. Here, we report upon the expression in E. coli cells of maltose-binding protein (MBP)- and glutathione S-transferase (GST)-fused cyclic amidohydrolase family enzymes, facilitating also for both simple purification and high-level expression. Interestingly, the native quaternary structure of each enzyme was maintained even when fused with MBP and GST. We also found that in fusion proteins the favorable biochemical properties of family enzymes such as, their optimal pHs, specific activities and kinetic properties were conserved compared to the native enzymes. In addition, MBP-fused enzymes showed remarkable folding ability in-vitro. Our findings, therefore, suggest that a previously unrecognized trait of this family, namely the ability to functional fusion with some other protein but yet to retain innate properties, is conserved. We described here the structural and evolutionary implications of the properties in this family enzyme.

• 한국미생물·생명공학회지
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• 제30권4호
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• pp.312-319
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• 2002

저온성 균인 Sporosarcina psychrophilia의 염색체 DNA를 추출하여 Sau3AI으로 부분 절단하고 pUC19 vector에 ligation 시킨 후, Escherichia coli pyrB mutant 균주에 형질전환하여 uracil이 없는 AB배지에서 생존하는 균주를 선택한 후, 그 plasmid를 분리하여 pSMI과 pSM2라고 명명하였다. 두 plasmid의 염기배열을 결정한 결과 pSM2 insert DNA는 pSMl insert DNA 부분을 포함하는 2,606 nucleotide 단편이었다. 염기서열을 분석하였을 때 이것은 1개의 완전한 open reading frame(ORF)과 2개의 부분 ORFs를 포함하고 있었다. 두 번째 위치한 완전한 ORF는 Bacillus caldolyticus aspartate transcarbamylase(pyrB)와 아미노산 서열 수준에서 59% 상동성을 보였고, 첫 번째와 세 번째 위치한 부분적 ORFs는 각각 Bacillus속의 uracil permease(pyrP)와 dihydoorotase(pyrC)와 높은 상동성을 보였다. 그리고 pyrB와 pyrP사이에 intergenic 부분에는 잠재적인 terminator, antiterminator, anti-antiterminator 구조를 포함하고 있었다. 이러한 결과는 S. psychrophilia pyrimidine 생합성에 관련된 유전자들은 다른 Bacillus속에서 알려진 바와 같이 유전자군을 형성하고 있을 것으로 추정했다. S. psychrophilia pyrB 유전자의 생성물을 과다발현 시키고 정제해서 그 단백질을 SDS-PAGE로 확인한 결과 27 kDa 부근에서 band를 확인할 수 있었으며, 정제한 단백질도 ATCase 효소활성을 지니고 있었다.