The crystal structure is reported of p‐hydroxybenzoate hydroxylase (PobA) from Pseudomonas putida, a possible drug target to combat tetracycline resistance, in complex with flavin adenine dinucleotide (FAD). The structure was refined at 2.2 Å resolution with four polypeptide chains in the asymmetric unit. Based on the results of pairwise structure alignments, PobA from P. putida is structurally very similar to PobA from P. fluorescens and from P. aeruginosa. Key residues in the FAD‐binding and substrate‐binding sites of PobA are highly conserved spatially across the proteins from all three species. Additionally, the structure was compared with two enzymes from the broader class of oxygenases: 2‐hydroxybiphenyl 3‐monooxygenase (HbpA) from P. nitroreducens and 2‐methyl‐3‐hydroxypyridine‐5‐carboxylic acid oxygenase (MHPCO) from Mesorhizobium japonicum. Despite having only 14% similarity in their primary sequences, pairwise structure alignments of PobA from P. putida with HbpA from P. nitroreducens and MHPCO from M. japonicum revealed local similarities between these structures. Key secondary‐structure elements important for catalysis, such as the βαβ fold, β‐sheet wall and α12 helix, are conserved across this expanded class of oxygenases.

中文翻译：

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恶臭假单胞菌的对羟基苯甲酸酯羟化酶（PobA）与其他假单胞菌属的PobA的结构比较。和其他单加氧酶。

据报道，恶臭假单胞菌的对羟基苯甲酸酯羟化酶（PobA）的晶体结构与黄素腺嘌呤二核苷酸（FAD）形成复合物，可对抗四环素耐药性。在不对称单元中具有四个多肽链的情况下，以2.2Å的分辨率精炼了结构。根据成对结构比对的结果，恶臭假单胞菌的PobA与荧光假单胞菌和铜绿假单胞菌的PobA在结构上非常相似。PobA的FAD结合位点和底物结合位点中的关键残基在所有三种物种的蛋白质中在空间上高度保守。此外，该结构与从更广泛的类氧酶的两种酶相比：从2-羟基联苯-3-单加氧酶（HBPA）P. nitroreducens和由2-甲基-3-羟基吡啶-5-羧酸氧酶（MHPCO）中慢生根瘤菌血吸虫。尽管在他们的一级序列仅具有14％的相似性，从POBA的成对结构校正恶臭假单胞菌从与HBPA P. nitroreducens和MHPCO从M.血吸虫揭示了这些结构之间的局部相似性。在这种扩展的加氧酶中，对于催化重要的关键二级结构元素（如βαβ折叠，β折叠壁和α12螺旋）得以保留。