Deletion of MSMEG_1350 in Mycobacterium smegmatis causes loss of epoxy-mycolic acids, fitness alteration at low temperature and resistance to a set of mycobacteriophages
Deletion of MSMEG_1350 in Mycobacterium smegmatis causes loss of epoxy-mycolic acids, fitness alteration at low temperature and resistance to a set of mycobacteriophages
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DOI：
10.1099/mic.0.000734
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发表时间：
2018-12-01
期刊：
影响因子：
2.8
通讯作者：
Morbidoni, Hector R.
中科院分区：
文献类型：
--
作者：
Di Capua, Cecilia B.;Belardinelli, Juan M.;Morbidoni, Hector R.
耻垢分枝杆菌本质上是耐thiacetazone，抗结核硫脲，但我们在这里报告，它会导致在液体培养基中的生长轻度抑制。由于分枝菌酸的生物合成受到影响，我们克隆并表达了耻垢分枝杆菌分枝菌酸甲基转移酶，假定为其他分枝杆菌物种中噻乙腙的靶标。在该分析期间，我们将MSMEG_1350鉴定为参与环氧分枝菌酸合成的甲基转移酶，因为其缺失导致其完全丧失。突变菌株的表型表征显示在所有温度下菌落形态改变，生长减少，在20 ℃下对SDS、亲脂性和大亲水性药物的敏感性略有增加，在37 ℃下几乎没有影响。亲本和突变株之间的生物膜形成，滑动运动或沉降率没有变化。有趣的是，我们发现几种分枝杆菌噬菌体在突变株中形成噬斑的能力严重降低。综上所述，我们的结果证明，尽管是一个次要组成部分的分枝菌酸池，环氧分枝菌是需要一个适当的组装和功能的细胞包膜。进一步的研究是必要的，以破译的作用，环氧霉菌在M。包皮垢细胞被膜。
Mycobacterium smegmatis is intrinsically resistant to thiacetazone, an anti-tubercular thiourea; however we report here that it causes a mild inhibition in growth in liquid medium. Since mycolic acid biosynthesis was affected, we cloned and expressed Mycobacterium smegmatis mycolic acid methyltransferases, postulated as targets for thiacetazone in other mycobacterial species. During this analysis we identified MSMEG_1350 as the methyltransferase involved in epoxy mycolic acid synthesis since its deletion led to their total loss. Phenotypic characterization of the mutant strain showed colony morphology alterations at all temperatures, reduced growth and a slightly increased susceptibility to SDS, lipophilic and large hydrophilic drugs at 20 degrees C with little effect at 37 degrees C. No changes were detected between parental and mutant strains in biofilm formation, sliding motility or sedimentation rate. Intriguingly, we found that several mycobacteriophages severely decreased their ability to form plaques in the mutant strain. Taken together our results prove that, in spite of being a minor component of the mycolic acid pool, epoxy-mycolates are required for a proper assembly and functioning of the cell envelope. Further studies are warranted to decipher the role of epoxy-mycolates in the M. smegmatis cell envelope.