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Investigation of organisms having unique selenium metabolic pathways and its application to bioremediation

具有独特硒代谢途径的生物体的研究及其在生物修复中的应用

基本信息

批准号：
18405042
负责人：
ESAKI Nobuyoshi
金额：
$ 9.46万
依托单位：
Kyoto University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2006
资助国家：
日本
起止时间：
2006 至 2007
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-18405042/
关键词：
selenium selenoprotein selenocysteine essential trace element metabolism 微生物

项目摘要

Selenium is an essential trace element with a variety of physiological role and is strictly discriminated from its cognate sulfur to be incorporated into a specific position of proteins as a selenocysteine residue. In this study, we investigated organisms having unique selenium metabolism pathway and analyzed the structure and function of novel enzymes involved in selenium metabolism.1. It is suggested that the synthesis of O-phosphoseryl-tRNA from seryl-tRNA by the catalysis of O-phosphosery1-tRNA kinase, (PSTK) is essential for the biosynthesis of archaeal selenocystey1-tRNA. However, our in vitro study with PAD, PSTK, and selenocysteine synthase (SecS) from the methanogenic thermophile Methanocaldococcus jannaschii revealed that the synthesis of selenocystey1-tRNA is able to proceed via two independent pathways: one is dependent on PSTK and SelD, and another depends on SecS and SelD.2. We searched far a bacterium with a unique selenoprotein and found that Geobacter sulfurreducens probably contains a novel c-type cytochrome-like selenoprotein. This protein termed GSU2937-GSU2936 has 5 CXXCH motifs in its N-terminal region, which is encoded by the ORF upstream of a UGA codon for selenocysteine insertion. The GSU2937-GSU2936 protein shows only less than 12% sequence identity with cytochrome c nitrite reductase and hydroxylamine oxidoreductase, which are known as multi-heme proteins, suggesting that it belongs to a novel member of a protein family.

硒是一种具有多种生理作用的必需微量元素，与其同族硫严格区分，以硒代半胱氨酸残基的形式掺入蛋白质的特定位置。本研究对具有独特硒代谢途径的生物体进行了研究，并对参与硒代谢的新酶的结构和功能进行了分析.研究表明，在古细菌硒代半胱氨酸tRNA的生物合成过程中，O-磷酸丝氨酰-tRNA的合成是必需的。然而，我们在体外研究PAD，PSTK，硒代半胱氨酸合酶（SecS）从产甲烷嗜热菌詹氏甲烷球菌揭示，硒代半胱氨酸1-tRNA的合成能够通过两个独立的途径进行：一个是依赖于PSTK和SelD，另一个依赖于SecS和SelD。通过对一株具有独特硒蛋白的细菌的研究，发现硫还原菌中可能含有一种新的C型细胞色素样硒蛋白。该蛋白称为GSU 2937-GSU 2936，在其N-末端区域具有5个CXXCH基序，其由用于硒代半胱氨酸插入的UGA密码子上游的ORF编码。GSU 2937-GSU 2936蛋白与细胞色素c亚硝酸还原酶和羟胺氧化还原酶（称为多血红素蛋白）仅显示出不到12%的序列同一性，这表明它属于蛋白质家族的新成员。