Crystal Structure of the First Plant Urease from Jack Bean: 83 Years of Journey from Its First Crystal to Molecular Structure
Crystal Structure of the First Plant Urease from Jack Bean: 83 Years of Journey from Its First Crystal to Molecular Structure
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DOI：
10.1016/j.jmb.2010.05.009
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发表时间：
2010-07-16
影响因子：
5.6
通讯作者：
Ponnuraj, Karthe
中科院分区：
文献类型：
--
作者：
Balasubramanian, Anuradha;Ponnuraj, Karthe
脲酶是一种镍依赖性金属酶，由植物、某些细菌和真菌合成。它催化尿素水解成氨和二氧化碳。虽然植物和细菌的尿素酶的氨基酸序列密切相关，但某些生物活性却有显著差异。植物尿素酶具有杀虫特性，而细菌尿素酶不具有杀虫特性，与其尿素分解活性无关。迄今为止，结构信息仅可用于细菌尿素酶，尽管刀豆尿素酶（Canavalia ensiformis; JBU）是研究得最好的植物尿素酶，是1926年第一个结晶的酶。为了更好地了解植物脲酶的生物学特性，包括杀虫活性的机制，我们对其中一些脲酶进行了结构研究。在这里，我们报告的晶体结构的JBU，第一个植物脲酶结构，在2.05埃分辨率。JBU的活性位点结构类似于含有双镍中心的细菌脲酶。JBU在其活性位点具有结合的磷酸盐和被β-巯基乙醇共价修饰的残基（Cys 592），并且迄今为止在细菌脲酶中未观察到伴随的多种抑制剂（磷酸盐和β-巯基乙醇）的结合。通过将JBU的结构信息与有关植物尿素酶杀虫特性的现有生物物理和生化数据相关联，我们假设位于植物尿素酶昆虫毒性肽区域的两亲性β-发夹可能形成膜插入β-桶，正如在β-孔中发现的那样-形成毒素。(C)2010爱思唯尔有限公司版权所有。
Urease, a nickel-dependent metalloenzyme, is synthesized by plants, some bacteria, and fungi. It catalyzes the hydrolysis of urea into ammonia and carbon dioxide. Although the amino acid sequences of plant and bacterial ureases are closely related, some biological activities differ significantly. Plant ureases but not bacterial ureases possess insecticidal properties independent of its ureolytic activity. To date, the structural information is available only for bacterial ureases although the jack bean urease (Canavalia ensiformis; JBU), the best-studied plant urease, was the first enzyme to be crystallized in 1926. To better understand the biological properties of plant ureases including the mechanism of insecticidal activity, we initiated the structural studies on some of them. Here, we report the crystal structure of JBU, the first plant urease structure, at 2.05 angstrom resolution. The active-site architecture of JBU is similar to that of bacterial ureases containing a bi-nickel center. JBU has a bound phosphate and covalently modified residue (Cys592) by beta-mercaptoethanol at its active site, and the concomitant binding of multiple inhibitors (phosphate and beta-mercaptoethanol) is not observed so far in bacterial ureases. By correlating the structural information of JBU with the available biophysical and biochemical data on insecticidal properties of plant ureases, we hypothesize that the amphipathic beta-hairpin located in the entomotoxic peptide region of plant ureases might form a membrane insertion beta-barrel as found in beta-pore-forming toxins. (C) 2010 Elsevier Ltd. All rights reserved.