描述的大肠杆菌RNA 3 '末端磷酸环化酶及其sigma54-regulated操纵子。
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Genschik P, Drabikowski K, Filipowicz W
描述的大肠杆菌RNA 3 '末端磷酸环化酶及其sigma54-regulated操纵子。
生物化学杂志。1998年9月25日,273(39):25516 - 26所示。
- PubMed ID
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9738023 (在PubMed]
- 文摘
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RNA 3 '末端磷酸环化酶催化的ATP-dependent转换3 '磷酸的2 ',3 '环磷酸二酯的各种RNA基质。最近的cDNA克隆人类环化酶编码表示,基因编码cyclase-like真核生物蛋白质是守恒的,细菌和古生菌。大肠杆菌的蛋白质编码基因过表达和RNA的3所示的磷酸酸环化酶活性(Genschik, P。比利,E。Swianiewicz, M。,Filipowicz EMBO j . 16 w (1997) 2955 - 2967)。分析需求和底物特异性的大肠杆菌蛋白质,提出了工作,表明人类细菌和酶的性质是相似的。ATP是最好的辅助因子(公里= 20 microM),而三磷酸鸟苷(公里= 100 microM)和其他核苷三磷酸腺苷(国家结核控制规划)法有效地减少。酶经历nucleotidylation alpha-32P ATP和的存在,一定程度上,也在其他国家结核控制规划。比较3 '磷酸化oligoribonucleotides和oligodeoxyribonucleotides相同的序列表明,后者至少300倍贫穷酶的底物。大肠杆菌环化酶基因,名叫rtcA形式的一部分,但一个个操纵子包含两个额外的开放阅读框(orf)。 The ORF positioned immediately upstream, named rtcB, encodes a protein that is also highly conserved between Eucarya, Bacteria, and Archaea. Another ORF, called rtcR, is positioned upstream of the rtcA/rtcB unit and is transcribed in the opposite direction. It encodes a protein having features of sigma54-dependent regulators. By overexpressing the N-terminally truncated form of RtcR, we demonstrate that this regulator indeed controls expression of rtcA and rtcB in a sigma54-dependent manner. Also consistent with the involvement of sigma54, the region upstream of the transcription start site of the rtcA/rtcB mRNA contains the -12 and -24 elements, TTGCA and TGGCA, respectively, characteristic of sigma54-dependent promoters. The cyclase gene is nonessential as demonstrated by knockout experiments. Possible functions of the cyclase in RNA metabolism are discussed.