Bacillus anthracis ω-amino acid:pyruvate transaminase employs a different mechanism for dual substrate recognition than other amine transaminases
Bacillus anthracis ω-amino acid:pyruvate transaminase employs a different mechanism for dual substrate recognition than other amine transaminases
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DOI：
10.1007/s00253-015-7275-9
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发表时间：
2016-05-01
影响因子：
5
通讯作者：
Hoehne, Matthias
中科院分区：
文献类型：
--
作者：
Steffen-Munsberg, Fabian;Matzel, Philipp;Hoehne, Matthias
要根据生物体或细菌群落的（Meta）基因组了解其代谢潜力，需要从氨基酸序列中可靠地预测酶的功能。除了预测算法的显著发展之外，与良好表征的酶具有低同一性的序列的底物范围通常仍然非常难以捉摸。从最近进行的PLP依赖性酶的结构功能分析研究中，我们鉴定了来自炭疽芽孢杆菌的推定转氨酶（Ban-TA），其晶体结构为3 N5 M（2011年保藏在蛋白质数据库中，但尚未发表）。Ban-TA的活性位点残基与相关（III类）转氨酶中的活性位点残基不同，从而阻止了功能预测。通过研究50种底物组合，揭示了其胺和ω-氨基酸：丙酮酸转氨酶活性。尽管Ban-TA在测试的底物中显示出相对窄的胺底物范围，但它接受2-丙胺，这是工业不对称胺合成的先决条件。结构信息暗示，所谓的双底物识别化学上不同的底物（即胺和氨基酸）不同于以前已知的酶。它缺乏通常保守的“翻转”精氨酸，这使得能够通过其在其他ω-氨基酸中的侧链柔性进行双底物识别：丙酮酸转氨酶。分子动力学研究表明，另一个精氨酸（R162）结合在Ban-TA中的ω-氨基酸，但胺和氨基酸结合不需要侧链运动。这些结果得到了诱变研究的支持，为B的功能提供了见解。炭疽酶，使相关蛋白质的功能预测，并扩大了有关ω-氨基酸和胺转化转氨酶的知识。
Understanding the metabolic potential of organisms or a bacterial community based on their (meta) genome requires the reliable prediction of an enzyme's function from its amino acid sequence. Besides a remarkable development in prediction algorithms, the substrate scope of sequences with low identity to well-characterized enzymes remains often very elusive. From a recently conducted structure function analysis study of PLP-dependent enzymes, we identified a putative transaminase from Bacillus anthracis (Ban-TA) with the crystal structure 3N5M (deposited in the protein data bank in 2011, but not yet published). The active site residues of Ban-TA differ from those in related (class III) transaminases, which thereby have prevented function predictions. By investigating 50 substrate combinations its amine and omega-amino acid:pyruvate transaminase activity was revealed. Even though Ban-TA showed a relatively narrow amine substrate scope within the tested substrates, it accepts 2-propylamine, which is a prerequisite for industrial asymmetric amine synthesis. Structural information implied that the so-called dual substrate recognition of chemically different substrates (i.e. amines and amino acids) differs from that in formerly known enzymes. It lacks the normally conserved 'flipping' arginine, which enables dual substrate recognition by its side chain flexibility in other omega-amino acid:pyruvate transaminases. Molecular dynamics studies suggested that another arginine (R162) binds omega-amino acids in Ban-TA, but no side chain movements are required for amine and amino acid binding. These results, supported by mutagenesis studies, provide functional insights for the B. anthracis enzyme, enable function predictions of related proteins, and broadened the knowledge regarding omega-amino acid and amine converting transaminases.