Srivastava Sonali, Chaudhary Sarika, Thukral Lipi, Shi Ce, Gupta Rinkoo D, Gupta Radhika, Priyadarshan K, Vats Archana, Haque Asfarul S, Sankaranarayanan Rajan, Natarajan Vivek T, Sharma Rakesh, Aldrich Courtney C, Gokhale Rajesh S
CSIR-Institute of Genomics and Integrative Biology, Mathura Road, New Delhi 110020, India; Academy of Scientific and Innovative Research, Rafi Marg, New Delhi 110001, India.
CSIR-Institute of Genomics and Integrative Biology, Mathura Road, New Delhi 110020, India.
Chem Biol. 2015 Dec 17;22(12):1577-87. doi: 10.1016/j.chembiol.2015.10.009. Epub 2015 Nov 25.
Mycobacterium tuberculosis (Mtb) can survive in hypoxic necrotic tissue by assimilating energy from host-derived fatty acids. While the expanded repertoire of β-oxidation auxiliary enzymes is considered crucial for Mtb adaptability, delineating their functional relevance has been challenging. Here, we show that the Mtb fatty acid degradation (FadAB) complex cannot selectively break down cis fatty acyl substrates. We demonstrate that the stereoselective binding of fatty acyl substrates in the Mtb FadB pocket is due to the steric hindrance from Phe287 residue. By developing a functional screen, we classify the family of Mtb Ech proteins as monofunctional or bifunctional enzymes, three of which complement the FadAB complex to degrade cis fatty acids. Crystal structure determination of two cis-trans enoyl coenzyme A (CoA) isomerases reveals distinct placement of active-site residue in Ech enzymes. Our studies thus reveal versatility of Mtb lipid-remodeling enzymes and identify an essential role of stand-alone cis-trans enoyl CoA isomerases in mycobacterial biology.
结核分枝杆菌（Mtb）可通过利用宿主来源脂肪酸中的能量在缺氧坏死组织中存活。虽然β-氧化辅助酶种类的扩展被认为对Mtb的适应性至关重要，但阐明它们的功能相关性一直具有挑战性。在此，我们表明Mtb脂肪酸降解（FadAB）复合物不能选择性地分解顺式脂肪酰底物。我们证明Mtb FadB口袋中脂肪酰底物的立体选择性结合是由于苯丙氨酸287残基的空间位阻。通过开发功能筛选，我们将Mtb Ech蛋白家族分类为单功能或双功能酶，其中三种可补充FadAB复合物以降解顺式脂肪酸。两种顺反烯酰辅酶A（CoA）异构酶的晶体结构测定揭示了Ech酶中活性位点残基的不同位置。因此，我们的研究揭示了Mtb脂质重塑酶的多功能性，并确定了独立的顺反烯酰CoA异构酶在分枝杆菌生物学中的重要作用。
