Crystal structure of hypothetical protein TTHB192 from Thermus thermophilus HB8 reveals a new protein family with an RNA recognition motif-like domain
Crystal structure of hypothetical protein TTHB192 from Thermus thermophilus HB8 reveals a new protein family with an RNA recognition motif-like domain
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DOI：
10.1110/ps.062131106
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发表时间：
2006-06-01
期刊：
影响因子：
8
通讯作者：
Kuramitsu, Seiki
中科院分区：
文献类型：
--
作者：
Ebihara, Akio;Yao, Min;Kuramitsu, Seiki
我们已经确定了1.9 Angstrom分辨率的Thermus HB8的假设蛋白TTHB192的晶体结构。该蛋白是含有大肠杆菌的成员，其中包含； 15个细菌起源的序列同源物。这些同源物具有很高的等电点。晶体结构表明，TTHB192由两个独立折叠的结构域组成，每个结构域都表现出一个类似铁氧还蛋白的褶皱，带有四链的反平行β片，由Alpha-Helices在一侧包装。这两个串联域相互面对，以生成一个beta表平台。 TTHB192显示出与性致命蛋白和聚（A）结合蛋白片段的总体结构相似性。这些蛋白质具有RNA结合活性，该蛋白质由Beta表平台支持，该平台由beta表面上具有签名序列基序的RNA识别基序域的两个串联重复序列形成。尽管TTHB192没有与RNA识别基序域相同的签名序列基序，但是在β-片平台上存在进化保守的基本贴片的存在可能与核酸结合的功能相关。该报告表明，TTHB192及其序列同源物采用RNA识别基序状结构域，并为该蛋白质家族提供了第一个可检验的功能假设。
We have determined the crystal structure of hypothetical protein TTHB192 from Thermus thermophilus HB8 at 1.9 angstrom resolution. This protein is a member of the Escherichia coli ygcH sequence family, which contains; 15 sequence homologs of bacterial origin. These homologs have a high isoelectric point. The crystal structure reveals that TTHB192 consists of two independently folded domains, and that each domain exhibits a ferredoxin-like fold with a four-stranded antiparallel beta-sheet packed on one side by alpha-helices. These two tandem domains face each other to generate a beta-sheet platform. TTHB192 displays overall structural similarity to Sex-lethal protein and poly(A)-binding protein fragments. These proteins have RNA binding activity which is supported by a beta-sheet platform formed by two tandem repeats of an RNA recognition motif domain with signature sequence motifs on the beta-sheet surface. Although TTHB192 does not have the same signature sequence motif as the RNA recognition motif domain, the presence of an evolutionarily conserved basic patch on the beta-sheet platform could be functionally relevant for nucleic acid-binding. This report shows that TTHB192 and its sequence homologs adopt an RNA recognition motif-like domain and provides the first testable functional hypothesis for this protein family.