Elucidation of a novel mechanism of macrolide resistance in Mycobacterium abscessus

项目总结： 脓肿分枝杆菌(Mab)是一种快速生长的NTM，可引起皮肤和软组织感染。 慢性肺损伤患者的肺部感染，如既往的肺结核和囊性肺炎 纤维化症。单抗是抗药性最强的微生物之一，使其感染 令人难以置信地难以治疗。虽然大环内酯类化合物是治疗非肿瘤肿瘤的基石，但它们是 对Mab无效。对大环内酯类药物的内在耐药性归因于大环内酯类药物的诱导表达 修改组成大环内酯结合部位的23S rRNA的甲基酶。到目前为止，这是唯一 已知的大环内酯类抗生素在单抗中的耐药机制。 我们已经确定了一个额外的决定因素MAB_3042c，它可以诱导大环内酯类药物耐药 在Mab。MAB_3042c与普遍保守的HflX蛋白同源，已被证明 起核糖体分裂因子的作用。HflX蛋白以前没有被认为与抗生素有关 抗性表明Mab_3402可能是一种新的HflX类型。然而，MAb_3402也显示出 类似于核糖体保护因子，其特征是插入到 新生多肽出口隧道(NPET)，并堵塞大环内酯类结合口袋。 在本项目中，我们将探讨单抗_3042在单抗对大环内酯类抗生素耐药中的作用。在目标1中，我们 将确定MAB_3042c在核糖体分裂和核糖体保护中的功能以及 确定这些功能在大环内酯类耐药性中的作用。在目标2中，我们将研究 受MAB_3042c影响的抗生素。这些发现将为长期结构提供一个平台- 对MAb_3402c依赖大环内酯类抗生素在单抗中耐药机制的研究

Project Summary: Mycobacterium abscessus (Mab) is a rapidly growing NTM causing skin and soft tissue infections and pulmonary infections in patients with chronic lung damage, such as prior tuberculosis and cystic fibrosis. Mab stands apart as one of the most antibiotic resistant microbial species, making its infections incredibly difficult to treat. Although macrolides are a cornerstone of therapy against NTMs, they are ineffective against Mab. Intrinsic resistance to macrolides is attributed to macrolide inducible expression of methylases that modify the 23S rRNA comprising the macrolide binding site. To date this is the only known mechanism of macrolide resistance in Mab. We have identified an additional determinant, MAB_3042c, that confers inducible macrolide resistance in Mab. MAB_3042c is homologous to the universally conserved HflX proteins which have been shown to function as ribosome splitting factors. HflX proteins have not been previously implicated in antibiotic resistance suggesting that Mab_3402 could be a novel type of HflX. However, Mab_3402 also shows similarity to ribosome protection factors, which are characterized by an extended loop that inserts into the nascent polypeptide exit tunnel (NPET) and occludes the binding pocket of macrolides. In this project we will explore the function of Mab_3042 in macrolide resistance in Mab. In Aim 1, we will determine the function of MAB_3042c in ribosome splitting and ribosome protection as well as determine the role of these functions in macrolide resistance. In Aim 2 we will study the spectrum of antibiotics that are affected by MAB_3042c. The findings will provide a platform for a long-term structure- function study to gain mechanistic insight into Mab_3402c dependent macrolide resistance in Mab.