• Title/Summary/Keyword: Bioengineering

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Asp97 is a Crucial Residue Involved in the Ligation of the [$Fe_4S_4$] Cluster of IscA from Acidithiobacillus ferrooxidans

  • Jiang, Huidan;Zhang, Xiaojian;Ai, Chenbing;Liu, Yuandong;Liu, Jianshe;Qiu, Guanahou;Zeng, Jia
    • Journal of Microbiology and Biotechnology
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    • v.18 no.6
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    • pp.1070-1075
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    • 2008

  • IscA was proposed to be involved in the iron-sulfur cluster assembly encoded by the iscSUA operon, but the role of IscA in the iron-sulfur cluster assembly still remains controversial. In our previous study, the IscA from A. ferrooxidans was successfully expressed in Escherichia coli, and purified to be a [$Fe_4S_4$] -cluster-containing protein. Cys35, Cys99, and Cys101 were important residues in ligating with the [$Fe_4S_4$] cluster. In this study, Asp97 was found to be another ligand for the iron-sulfur cluster binding according to site-directed mutagenesis results. Molecular modeling for the IscA also showed that Asp97 was a strong ligand with the [$Fe_4S_4$] cluster, which was in good agreement with the experimental results. Thus, the [$Fe_4S_4$] cluster in IscA from A. ferrooxidans was ligated by three cysteine residues and one aspartic acid.

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Biodegradation of Di-n-Butyl Phthalate by Rhodococcus sp. JDC-11 and Molecular Detection of 3,4-Phthalate Dioxygenase Gene

  • Jin, De-Cai;Liang, Ren-Xing;Dai, Qin-Yun;Zhang, Rui-Yong;Wu, Xue-Ling;Chao, Wei-Liang
    • Journal of Microbiology and Biotechnology
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    • v.20 no.10
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    • pp.1440-1445
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    • 2010

  • Rhodococcus sp. JDC-11, capable of utilizing di-n-butyl phthalate (DBP) as the sole source of carbon and energy, was isolated from sewage sludge and confirmed mainly based on 16S rRNA gene sequence analysis. The optimum pH, temperature, and agitation rate for DBP degradation by Rhodococcus sp. JDC-11 were 8.0, $30^{\circ}C$, and 175 rpm, respectively. In addition, low concentrations of glucose were found to inhibit the degradation of DBP, whereas high concentrations of glucose increased its degradation. Meanwhile, a substrate utilization test showed that JDC-11 was also able to utilize other phthalates. The major metabolites of DBP degradation were identified as monobutyl phthalate and phthalic acid by gas chromatography-mass spectrometry, allowing speculation on the tentative metabolic pathway of DBP degradation by Rhodococcus sp. JDC-11. Using a set of new degenerate primers, a partial sequence of the 3,4-phthalate dioxygenase gene was obtained from JDC-11. Moreover, a sequence analysis revealed that the phthalate dioxygenase gene of JDC-11 was highly homologous to the large subunit of the phthalate dioxygenase from Rhodococcus coprophilus strain G9.

  • https://doi.org/10.4014/jmb.1004.04034 인용 PDF KSCI