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首页> 外文期刊>Acta crystallographica.Section D Biological crystallography. >Structural characteristics of alkaline phosphatase from the moderately halophilic bacterium Halomonas sp. 593
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Structural characteristics of alkaline phosphatase from the moderately halophilic bacterium Halomonas sp. 593

机译：碱性磷酸酶的结构特点中度嗜盐菌Halomonas sp 593。

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摘要

Alkaline phosphatase (AP) from the moderate halophilic bacterium Halomonas sp. 593 (HaAP) catalyzes the hydrolysis of phosphomonoesters over a wide salt-concentration range (1-4 M NaCl). In order to clarify the structural basis of its halophilic characteristics and its wide-range adaptation to salt concentration, the tertiary structure of HaAP was determined by X-ray crystallography to 2.1 ? resolution. The unit cell of HaAP contained one dimer unit corresponding to the biological unit. The monomer structure of HaAP contains a domain comprised of an 11-stranded β-sheet core with 19 surrounding α-helices similar to those of APs from other species, and a unique 'crown' domain containing an extended 'arm' structure that participates in formation of a hydrophobic cluster at the entrance to the substrate-binding site. The HaAP structure also displays a unique distribution of negatively charged residues and hydrophobic residues in comparison to other known AP structures. AP from Vibrio sp. G15-21 (VAP; a slight halophile) has the highest similarity in sequence (70.0% identity) and structure (Cα r.m.s.d. of 0.82 ? for the monomer) to HaAP. The surface of the HaAP dimer is substantially more acidic than that of the VAP dimer (144 exposed Asp/Glu residues versus 114, respectively), and thus may enable the solubility of HaAP under high-salt conditions. Conversely, the monomer unit of HaAP formed a substantially larger hydrophobic interior comprising 329 C atoms from completely buried residues, whereas that of VAP comprised 264 C atoms, which may maintain the stability of HaAP under low-salt conditions. These characteristics of HaAP may be responsible for its unique functional adaptation permitting activity over a wide range of salt concentrations.
机译：从温和碱性磷酸酶(美联社)嗜盐细菌Halomonas sp。593(兴隆)催化phosphomonoesters的水解盐浓度范围宽(1 - 4米氯化钠)。和它的嗜盐的特征宽量程适应盐浓度,兴隆的三级结构是由2.1 x射线晶体学吗?包含一个二聚体单元晶胞的兴隆对应的生物单位。兴隆结构包含一个域组成的一个11-strandedβ片核心周围有19个α螺旋的APs从其他类似物种,一个独特的“皇冠”域包含一个扩展的“手臂”结构,参与疏水性集群的形成substrate-binding入口网站。结构也显示一个独特的分布带负电荷的残留物和疏水性残留相比其他已知的美联社结构。轻微的喜盐生物)最高的相似度身份序列(70.0%)和结构(Cαr.m.s.d. 0.82吗?兴隆二聚体表面是更多VAP的酸性比二聚体(144暴露分别为Asp / Glu残留物和114),和从而可以使兴隆的溶解度高盐条件。一个兴隆形成较大单位疏水室内329 C原子组成完全埋残留,而VAP由264 C原子,这可能维持在低盐条件下稳定性的兴隆。这些特征的兴隆可能是负责任的以其独特的功能适应性允许活动在一个广泛的盐浓度。

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