Pseudaminic acid is a non-mammalian sugar found in the surface glycoconjugates of many bacteria, including several human pathogens, and is a virulence factor thought to facilitate immune evasion. The final step in the biosynthesis of the nucleotide activated form of the sugar, CMP-Pse5Ac7Ac is performed by a CMP-Pse5Ac7Ac synthetase (PseF). Here we present the biochemical and structural characterization of PseF from Aeromonas caviae (AcPseF), with AcPseF displaying metal-dependent activity over a broad pH and temperature range. Upon binding to CMP-Pse5Ac7Ac, AcPseF undergoes dynamic movements akin to other CMP-ulosonic acid synthetases. The enzyme clearly discriminates Pse5Ac7Ac from other ulosonic acids, through active site interactions with side-chain functional groups and by positioning the molecule in a hydrophobic pocket. Finally, we show that AcPseF binds the CMP-Pse5Ac7Ac side chain in the lowest energy conformation, a trend that we observed in the structures of other enzymes of this class.

中文翻译：

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CMP-假丹霉素酸合成酶 （PseF） 的结构解剖


假丹米酸是一种非哺乳动物糖，存在于许多细菌（包括几种人类病原体）的表面糖缀合物中，是一种被认为可促进免疫逃逸的毒力因子。糖的核苷酸激活形式 CMP-Pse5Ac7Ac 生物合成的最后一步由 CMP-Pse5Ac7Ac 合成酶 （PseF） 进行。在这里，我们介绍了来自气单胞菌 （AcPseF） 的 PseF 的生化和结构表征，其中 AcPseF 在较宽的 pH 值和温度范围内显示出金属依赖性活性。与 CMP-Pse5Ac7Ac 结合后，AcPseF 发生类似于其他 CMP-磺酸合成酶的动态运动。该酶通过与侧链官能团的活性位点相互作用以及通过将分子定位在疏水口袋中，清楚地将 Pse5Ac7Ac 与其他磺酸区分开来。最后，我们表明 AcPseF 以最低能量构象结合 CMP-Pse5Ac7Ac 侧链，我们在此类其他酶的结构中观察到了这一趋势。