The rv1184c locus encodes Chp2, an acyltransferase in Mycobacterium tuberculosis polyacyltrehalose lipid biosynthesis.
The rv1184c locus encodes Chp2, an acyltransferase in Mycobacterium tuberculosis polyacyltrehalose lipid biosynthesis.
复制标题
rv1184c 基因座编码 Chp2，这是结核分枝杆菌聚酰基海藻糖脂质生物合成中的一种酰基转移酶。
DOI：
10.1128/jb.02015-14
复制
发表时间：
2015
影响因子：
3.2
通讯作者：
Seeliger,JessicaC
中科院分区：
文献类型：
--
作者：
Touchette,MeganH;Holsclaw,CynthiaM;Previti,MaryL;Solomon,VivenC;Leary,JulieA;Bertozzi,CarolynR;Seeliger,JessicaC
海藻糖糖脂存在于棒状杆菌亚目的许多细菌中，但甲基支链酰基海藻糖仅限于毒性物种，如人类病原体结核分枝杆菌。In M.在结核病中，酰基转移酶PapA3催化二酰基海藻糖（DAT）的形成，但尚未鉴定出负责导致最终产物聚酰基海藻糖（PAT）的下游反应的酶。PAT生物合成基因位点与另一种海藻糖糖脂硫脂1的基因位点相似。最近，Chp 1被鉴定为硫脂1生物合成的末端酰基转移酶。在这里，我们提供的证据表明，同源Chp2（Rv1184c）是必不可少的PAT生物合成的最后步骤。Chp2的破坏导致PAT和一种新的四酰基海藻糖物质TetraAT的丢失，以及DAT的积累，暗示Chp2是PapA3下游的酰基转移酶。假定的脂质转运蛋白MmpL10的破坏导致类似的表型。因此，Chp2活性似乎受到MmpL10的调节，其关系类似于磺脂1生物合成中Chp1和MmpL8之间的关系。Chp2定位于细胞包膜部分，与其在DAT修饰中的作用以及与MmpL10的可能的调节相互作用一致。标记纯化Chp2的活性为基础的探针是依赖于预测的催化残基Ser141的存在下，并抑制脂肪酶抑制剂四氢lipstatin（THL）。THL处理M.结核病导致Chp2相对于PapA3的选择性抑制，证实Chp2是丝氨酸水解酶超家族的成员。使用直链类似物进行酰基转移酶活性的体外重建的努力是不成功的，这表明Chp2对天然甲基支链底物具有特异性。
Trehalose glycolipids are found in many bacteria in the suborder Corynebacterineae, but methyl-branched acyltrehaloses are exclusive to virulent species such as the human pathogen Mycobacterium tuberculosis. In M. tuberculosis, the acyltransferase PapA3 catalyzes the formation of diacyltrehalose (DAT), but the enzymes responsible for downstream reactions leading to the final product, polyacyltrehalose (PAT), have not been identified. The PAT biosynthetic gene locus is similar to that of another trehalose glycolipid, sulfolipid 1. Recently, Chp1 was characterized as the terminal acyltransferase in sulfolipid 1 biosynthesis. Here we provide evidence that the homologue Chp2 (Rv1184c) is essential for the final steps of PAT biosynthesis. Disruption ofchp2led to the loss of PAT and a novel tetraacyltrehalose species, TetraAT, as well as the accumulation of DAT, implicating Chp2 as an acyltransferase downstream of PapA3. Disruption of the putative lipid transporter MmpL10 resulted in a similar phenotype. Chp2 activity thus appears to be regulated by MmpL10 in a relationship similar to that between Chp1 and MmpL8 in sulfolipid 1 biosynthesis. Chp2 is localized to the cell envelope fraction, consistent with its role in DAT modification and possible regulatory interactions with MmpL10. Labeling of purified Chp2 by an activity-based probe was dependent on the presence of the predicted catalytic residue Ser141 and was inhibited by the lipase inhibitor tetrahydrolipstatin (THL). THL treatment of M. tuberculosis resulted in selective inhibition of Chp2 over PapA3, confirming Chp2 as a member of the serine hydrolase superfamily. Efforts to producein vitroreconstitution of acyltransferase activity using straight-chain analogues were unsuccessful, suggesting that Chp2 has specificity for native methyl-branched substrates.