Insights into the smooth-to-rough transitioning in Mycobacterium bolletii unravels a functional Tyr residue conserved in all mycobacterial MmpL family members
Insights into the smooth-to-rough transitioning in Mycobacterium bolletii unravels a functional Tyr residue conserved in all mycobacterial MmpL family members
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DOI：
10.1111/mmi.13283
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发表时间：
2016-03-01
影响因子：
3.6
通讯作者：
Kremer, Laurent
中科院分区：
文献类型：
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作者：
Bernut, Audrey;Viljoen, Albertus;Kremer, Laurent
在分枝杆菌中，MmpL蛋白代表参与复杂细胞包膜生物合成的关键组分。一株自发粗糙型分枝杆菌亚种的全基因组分析bolletii鉴定了对MmpL家族蛋白的功能至关重要的保守酪氨酸。同基因平滑（S）和粗糙（R）变体的区别在于与MmpL 4a中的Y842 H取代相关的单个突变。这种突变导致糖肽脂生产/运输的R变体和增益的能力，以生产线在体外的缺陷。在斑马鱼中，发现M. bolletiiiR变体的毒力超过亲本S菌株，涉及大量产生蛇形索、脓肿形成和快速幼虫死亡。重要的是，这一发现使我们能够证明Tyr 842在几种不同的MmpL蛋白中的重要作用，包括结核分枝杆菌MmpL 3。MmpL 4a和MmpL 3的结构同源性模型鉴定了位于彼此面对的跨膜区TM 10和TM 4中的另外两个关键残基。我们建议，这些中央残基的质子动力，供应能源基板运输的一部分。因此，我们提供了重要的见解MmpL蛋白作为脂质转运蛋白和分枝杆菌的毒力决定因素的机制/结构方面。
In mycobacteria, MmpL proteins represent key components that participate in the biosynthesis of the complex cell envelope. Whole genome analysis of a spontaneous rough morphotype variant of Mycobacterium abscessus subsp. bolletii identified a conserved tyrosine that is crucial for the function of MmpL family proteins. Isogenic smooth (S) and rough (R) variants differed by a single mutation linked to a Y842H substitution in MmpL4a. This mutation caused a deficiency in glycopeptidolipid production/transport in the R variant and a gain in the capacity to produce cords in vitro. In zebrafish, increased virulence of the M.bolletiiR variant over the parental S strain was found, involving massive production of serpentine cords, abscess formation and rapid larval death. Importantly, this finding allowed us to demonstrate an essential role of Tyr842 in several different MmpL proteins, including Mycobacterium tuberculosisMmpL3. Structural homology models of MmpL4a and MmpL3 identified two additional critical residues located in the transmembrane regions TM10 and TM4 that are facing each other. We propose that these central residues are part of the proton-motive force that supplies the energy for substrate transport. Hence, we provide important insights into mechanistic/structural aspects of MmpL proteins as lipid transporters and virulence determinants in mycobacteria.