The MmpL3 interactome

摘要 结核病是由于传染病导致死亡的主要原因之一，尽管抗结核药物是可用的。 抗结核药结核分枝杆菌（Mtb）的细胞包膜以其丰富的 分枝菌酸（MA），这是必不可少的分枝杆菌的生存能力。分枝杆菌细胞被膜 非常疏水，有助于毒力和抗生素抗性。然而，糖复合物 和其他物种特异性脂质跨内膜运输，用于细胞包膜生物合成。 不完全理解。 最近的研究表明，分枝杆菌膜蛋白大（MmpL）转运蛋白输出脂质 在分枝杆菌细胞质中合成，用于掺入细胞包膜。这些运输机是 因此对于细菌的生存力和毒力很重要。MmpL3是本提案的重点，至关重要， 转运海藻糖单霉菌酸酯（TMM）、海藻糖二霉菌酸酯（TDM）的前体和 分枝菌酰阿拉伯半乳聚糖肽聚糖（mAGP）。MmpL3输出的确切机制仍然难以捉摸。 RND家族蛋白通常具有协助底物转运的衔接蛋白。中提出 我们的初步数据和最近的出版物，我们确定了几个脂蛋白与MmpL3和 MmpL11.我们表征了Mtb lpqN突变体，并证明LpqN具有脂质结合口袋， 与Ag85分枝菌酰转移酶相互作用。基于这些数据，我们提出了一个模型， 脂蛋白与MmpL蛋白形成复合物以促进脂质分泌和定位。 我们的假设是，MmpL3与脂蛋白相互作用，促进TMM的输出， 进入细胞膜。拟议中的研究将结合联合收割机生化和遗传的方法 以鉴定与MmpL3复合以促进底物转运的蛋白质。 .

ABSTRACT Tuberculosis is one of the leading causes of death due to infectious disease despite the availability of anti- tubercular drugs. The cell envelope of Mycobacterium tuberculosis (Mtb) is notable for the abundance of mycolic acids (MAs), which are essential to mycobacterial viability. The mycobacterial cell envelope is extremely hydrophobic, contributes to virulence and antibiotic resistance. Yet, exactly how glycoconjugates and other species-specific lipids are transported across the inner membrane for cell envelope biosynthesis is incompletely understood. Recent work shows that the Mycobacterial membrane protein Large (MmpL) transporters export lipids synthesized in the mycobacterial cytoplasm for incorporation into the cell envelope. These transporters are therefore important for bacterial viability and virulence. MmpL3, the focus of this proposal, is essential and required for transport of trehalose monomycolate (TMM), the precursor of trehalose dimycolate (TDM) and mycolyl arabinogalactan peptidoglycan (mAGP). The exact mechanism of MmpL3 export remains elusive. RND family proteins typically possess adaptor proteins that assist in substrate transport. As presented in our preliminary data and recent publication, we identified several lipoproteins that interact with MmpL3 and MmpL11. We characterized an Mtb lpqN mutant and demonstrated that LpqN has a lipid binding pocket and interacts with the Ag85 mycolyl transferases. Based on these data, we propose a model where mycobacterial lipoproteins form a complex with MmpL protein to promote lipid secretion and localization. Our hypothesis is that MmpL3 interacts with lipoproteins that facilitate export of TMM and its incorporation into the cell envelope. The proposed study will combine biochemical and genetic approaches to identify proteins that complex with MmpL3 to facilitate substrate transport. .