Mycobacterium tuberculosis thymidylate synthase gene thyX is essential and potentially bifunctional, while thyA deletion confers resistance to p-aminosalicylic acid.
Mycobacterium tuberculosis thymidylate synthase gene thyX is essential and potentially bifunctional, while thyA deletion confers resistance to p-aminosalicylic acid.
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DOI：
10.1099/mic.0.053983-0
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发表时间：
2012-02
期刊：
影响因子：
--
通讯作者：
Davis EO
中科院分区：
文献类型：
--
作者：
Fivian-Hughes AS;Houghton J;Davis EO
胸苷合成酶(TS)催化脱氧胸苷单磷酸(DTMP或胸苷)的生物合成，对DNA复制和修复具有重要作用。已经描述了两种不同类型的TS蛋白(Thya和ThyX)，它们具有不同的酶机制和无关的结构。分枝杆菌是不同寻常的，因为它们同时编码Thya和Thyx，其生物学意义尚不清楚。结核分枝杆菌ThyX被认为是必不可少的，也是一个潜在的药物靶点。因此，我们分析了结核分枝杆菌Thya和ThyX的表达水平，它们在发病机制中的重要性和作用。我们发现Thya和Thyx在体外都有表达，并且这种表达在小鼠巨噬细胞中显著增加。在所有的测试条件下，Thya的表达都超过了Thyx。突变研究表明，结核分枝杆菌胸腺毒素是必不可少的，证实了这种酶是一个看似合理的药物靶点。在Thya存在的情况下对结核分枝杆菌Thyx的要求意味着Thyx的基本功能不是DTMP合成酶。我们成功地从结核分枝杆菌基因组中删除了Thya，这种缺失导致了在体内没有观察到的体外生长缺陷。据推测，Thyx在结核分枝杆菌ΔThya内以足够的速度在体内发挥TS活性，以满足正常生长，但在体外的速度并不理想。我们还证明了Thya缺失使结核分枝杆菌对p-氨基水杨酸产生耐药性，互补研究表明Thya T202A和V261G似乎分别具有功能性和非功能性。
Thymidylate synthase (TS) enzymes catalyse the biosynthesis of deoxythymidine monophosphate (dTMP or thymidylate), and so are important for DNA replication and repair. Two different types of TS proteins have been described (ThyA and ThyX), which have different enzymic mechanisms and unrelated structures. Mycobacteria are unusual as they encode both thyA and thyX, and the biological significance of this is not yet understood. Mycobacterium tuberculosis ThyX is thought to be essential and a potential drug target. We therefore analysed M. tuberculosis thyA and thyX expression levels, their essentiality and roles in pathogenesis. We show that both thyA and thyX are expressed in vitro, and that this expression significantly increased within murine macrophages. Under all conditions tested, thyA expression exceeded that of thyX. Mutational studies show that M. tuberculosis thyX is essential, confirming that the enzyme is a plausible drug target. The requirement for M. tuberculosis thyX in the presence of thyA implies that the essential function of ThyX is something other than dTMP synthase. We successfully deleted thyA from the M. tuberculosis genome, and this deletion conferred an in vitro growth defect that was not observed in vivo. Presumably ThyX performs TS activity within M. tuberculosis ΔthyA at a sufficient rate in vivo for normal growth, but the rate in vitro is less than optimal. We also demonstrate that thyA deletion confers M. tuberculosis p-aminosalicylic acid resistance, and show by complementation studies that ThyA T202A and V261G appear to be functional and non-functional, respectively.
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影响因子：
3.1
作者：
Fontan, Patricia;Aris, Virginie;Smith, Issar
通讯作者：
Smith, Issar
影响因子：
3.2
作者：
Guo, Xinzheng V.;Monteleone, Mercedes;Schnappinger, Dirk
通讯作者：
Schnappinger, Dirk
影响因子：
2.9
作者：
Agrawal, N;Lesley, SA;Kohen, A
通讯作者：
Kohen, A
DOI：
10.1385/0-89603-471-2:285
发表时间：
1998-01-01
期刊：
MYCOBACTERIA PROTOCOLS
影响因子：
--
作者：
Butcher, PD;Mangan, JA;Monahan, IM
通讯作者：
Monahan, IM
影响因子：
14.9
作者：
Chuchana, Paul;Marchand, Dorian;Garcia-Sanz, Jose A.
通讯作者：
Garcia-Sanz, Jose A.