The Leishmania nicotinamidase is essential for NAD+ production and parasite proliferation
The Leishmania nicotinamidase is essential for NAD+ production and parasite proliferation
复制标题
DOI：
10.1111/j.1365-2958.2011.07799.x
复制
发表时间：
2011-10-01
影响因子：
3.6
通讯作者：
Vergnes, B.
中科院分区：
文献类型：
--
作者：
Gazanion, E.;Garcia, D.;Vergnes, B.
NAD（+）是一种在所有活细胞的细胞代谢和能量产生中起重要作用的中心辅因子。基于基因组学的NAD（+）代谢重建显示，利什曼原虫寄生虫是NAD（+）营养缺陷型。因此，这些寄生虫需要从其宿主环境中同化NAD（+）前体（烟酰胺、烟酸、烟酰胺核苷），以通过补救途径合成NAD（+）。烟酰胺酶是该补救途径的关键酶，其催化烟酰胺（NAm）转化为烟酸（Na），并且在高等真核生物中不存在。我们在这里提出的婴儿利什曼原虫烟酰胺酶（LiPNC 1）的生化和功能特性。Lipnc1无效突变体的产生导致NAD（+）含量的降低，与具有广泛生长滞后期的代谢关闭样表型相关。这两种表型都可以通过添加回构建体或通过添加外源性Na来拯救。此外，Lipnc1无效突变体无法在小鼠实验模型中建立持续感染。总之，这些结果表明，NAD（+）稳态是利什曼原虫生物学和毒力的基本组成部分，NAm构成其在哺乳动物宿主中的主要NAD（+）来源。我们解决的LiPNC 1的晶体结构现在允许针对这个新的有前途的治疗靶点设计合理的抑制剂。
NAD(+) is a central cofactor that plays important roles in cellular metabolism and energy production in all living cells. Genomics-based reconstruction of NAD(+) metabolism revealed that Leishmania protozoan parasites are NAD(+) auxotrophs. Consequently, these parasites require assimilating NAD(+) precursors (nicotinamide, nicotinic acid, nicotinamide riboside) from their host environment to synthesize NAD(+) by a salvage pathway. Nicotinamidase is a key enzyme of this salvage pathway that catalyses conversion of nicotinamide (NAm) to nicotinic acid (Na), and that is absent in higher eukaryotes. We present here the biochemical and functional characterizations of the Leishmania infantum nicotinamidase (LiPNC1). Generation of Lipnc1 null mutants leads to a decrease in NAD(+) content, associated with a metabolic shutdown-like phenotype with an extensive lag phase of growth. Both phenotypes could be rescued by an add-back construct or by addition of exogenous Na. In addition, Lipnc1 null mutants were unable to establish a sustained infection in a murine experimental model. Altogether, these results illustrate that NAD(+) homeostasis is a fundamental component of Leishmania biology and virulence, and that NAm constitutes its main NAD(+) source in the mammalian host. The crystal structure of LiPNC1 we solved allows now the design of rational inhibitors against this new promising therapeutic target.