Rife Chris L, Parsons James F, Xiao Gaoyi, Gilliland Gary L, Armstrong Richard N
Department of Biochemistry and the Center in Molecular Toxicology, Vanderbilt University School of Medicine, Nashville Tennessee 37232-0146, USA.
Proteins. 2003 Dec 1;53(4):777-82. doi: 10.1002/prot.10452.
Multiple sequence alignments of the eight glutathione (GSH) transferase homologues encoded in the genome of Escherichia coli were used to define a consensus sequence for the proteins. The consensus sequence was analyzed in the context of the three-dimensional structure of the gst gene product (EGST) obtained from two different crystal forms of the enzyme. The enzyme consists of two domains. The N-terminal region (domain I) has a thioredoxin-like alpha/beta-fold, while the C-terminal domain (domain II) is all alpha-helical. The majority of the consensus residues (12/17) reside in the N-terminal domain. Fifteen of the 17 residues are involved in hydrophobic core interactions, turns, or electrostatic interactions between the two domains. The results suggest that all of the homologues retain a well-defined group of structural elements both in and between the N-terminal alpha/beta domain and the C-terminal domain. The conservation of two key residues for the recognition motif for the gamma-glutamyl-portion of GSH indicates that the homologues may interact with GSH or GSH analogues such as glutathionylspermidine or alpha-amino acids. The genome context of two of the homologues forms the basis for a hypothesis that the b2989 and yibF gene products are involved in glutathionylspermidine and selenium biochemistry, respectively.
利用大肠杆菌基因组中编码的8种谷胱甘肽（GSH）转移酶同系物的多序列比对来确定这些蛋白质的共有序列。在从该酶的两种不同晶体形式获得的gst基因产物（EGST）的三维结构背景下分析该共有序列。该酶由两个结构域组成。N端区域（结构域I）具有硫氧还蛋白样的α/β折叠，而C端结构域（结构域II）全是α螺旋。大多数共有残基（12/17）位于N端结构域。17个残基中的15个参与两个结构域之间的疏水核心相互作用、转角或静电相互作用。结果表明，所有同系物在N端α/β结构域和C端结构域内部及之间都保留了一组定义明确的结构元件。谷胱甘肽γ-谷氨酰部分识别基序的两个关键残基的保守性表明，这些同系物可能与谷胱甘肽或谷胱甘肽类似物如谷胱甘肽亚精胺或α-氨基酸相互作用。其中两个同系物的基因组背景构成了一个假说的基础，即b2989和yibF基因产物分别参与谷胱甘肽亚精胺和硒生物化学过程。
