Crystal structure of TTHA0252 from Thermus thermophilus HB8, a RNA degradation protein of the metallo-β-lactamase superfamily
Crystal structure of TTHA0252 from Thermus thermophilus HB8, a RNA degradation protein of the metallo-β-lactamase superfamily
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DOI：
10.1093/jb/mvj183
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发表时间：
2006-10-01
影响因子：
2.7
通讯作者：
Masui, Ryoji
中科院分区：
文献类型：
--
作者：
Ishikawa, Hirohito;Nakagawa, Noriko;Masui, Ryoji
在细菌RNA代谢中，mRNA降解是基因表达的重要过程。最近，一种新型核糖核酸酶 (RNase) 属于金属-β-内酰胺酶超家族中的 P-CASP 家族，被鉴定为 RNase E 的功能同源物，RNase E 是大肠杆菌中 mRNA 降解的主要成分。在这里，我们确定了来自嗜热栖热菌 11138 的 TTHA0252 的晶体结构，这是 P-CASP 家族蛋白三级结构的首次报道。 TTHA0252 包含两个独立的结构域：金属-β-内酰胺酶结构域和“钳”结构域。该酶的活性位点位于两个结构域之间的裂缝中，其中包括由七个保守残基协调的两个锌离子。尽管这种构型与其他 β-内酰胺酶的构型相似，但 TTHA0252 具有 β-CASP 家族的一个保守的组氨酸残基特征作为配体。我们还检测了 TTHA0252 针对嗜热链球菌 rRNA 的核酸酶活性。我们的结果揭示了具有 β-CASP 折叠的新型 RNase E 样酶的结构和功能。
In bacterial RNA metabolism, mRNA degradation is an important process for gene expression. Recently, a novel ribonuclease (RNase), belonging to the P-CASP family within the metallo-beta-lactamase superfamily, was identified as a functional homologue of RNase E, a major component for mRNA degradation in Escherichia coli. Here, we have determined the crystal structure of TTHA0252 from Thermus thermophilus 11138, which represents the first report of the tertiary structure of a P-CASP family protein. TTHA0252 comprises two separate domains: a metallo-beta-lactamase domain and a "clamp" domain. The active site of the enzyme is located in a cleft between the two domains, which includes two zinc ions coordinated by seven conserved residues. Although this configuration is similar to those of other beta-lactamases, TTHA0252 has one conserved His residue characteristic of the beta-CASP family as a ligand. We also detected nuclease activity of TTHA0252 against rRNAs of T. thermophilus. Our results reveal structural and functional aspects of novel RNase E-like enzymes with a beta-CASP fold.