Martin Jessica L, Yates Phillip A, Boitz Jan M, Koop Dennis R, Fulwiler Audrey L, Cassera Maria Belen, Ullman Buddy, Carter Nicola S
Department of Biochemistry and Molecular Biology, Oregon Health & Science University, 3181 SW Sam Jackson Park Road, Portland, OR, 97239-3098, USA.
Physiology and Pharmacology, Oregon Health & Science University, 3181 SW Sam Jackson Park Road, Portland, OR, 97239-3098, USA.
Mol Microbiol. 2016 Jul;101(2):299-313. doi: 10.1111/mmi.13390. Epub 2016 May 3.
Purine salvage by Leishmania is an obligatory nutritional process that impacts both cell viability and growth. Previously, we have demonstrated that the removal of purines in culture provokes significant metabolic changes that enable Leishmania to survive prolonged periods of purine starvation. In order to understand how Leishmania sense and respond to changes in their purine environment, we have exploited several purine pathway mutants, some in which adenine and guanine nucleotide metabolism is uncoupled. While wild type parasites grow in any one of a variety of naturally occurring purines, the proliferation of these purine pathway mutants requires specific types or combinations of exogenous purines. By culturing purine pathway mutants in high levels of extracellular purines that are either permissive or non-permissive for growth and monitoring for previously defined markers of the adaptive response to purine starvation, we determined that adaptation arises from a surveillance of intracellular purine nucleotide pools rather than from a direct sensing of the extracellular purine content of the environment. Specifically, our data suggest that perturbation of intracellular adenine-containing nucleotide pools provides a crucial signal for inducing the metabolic changes necessary for the long-term survival of Leishmania in a purine-scarce environment.
利什曼原虫的嘌呤补救是一个影响细胞活力和生长的必需营养过程。此前，我们已经证明，在培养物中去除嘌呤会引发显著的代谢变化，使利什曼原虫能够在长时间的嘌呤饥饿中存活。为了了解利什曼原虫如何感知并响应其嘌呤环境的变化，我们利用了几种嘌呤途径突变体，其中一些突变体中腺嘌呤和鸟嘌呤核苷酸代谢是解偶联的。野生型寄生虫能在多种天然存在的嘌呤中的任何一种中生长，而这些嘌呤途径突变体的增殖则需要特定类型或组合的外源性嘌呤。通过在对生长允许或不允许的高水平细胞外嘌呤中培养嘌呤途径突变体，并监测先前定义的对嘌呤饥饿的适应性反应标志物，我们确定适应性源于对细胞内嘌呤核苷酸池的监测，而不是对环境中细胞外嘌呤含量的直接感知。具体而言，我们的数据表明，细胞内含腺嘌呤核苷酸池的扰动为诱导利什曼原虫在嘌呤缺乏环境中长期存活所需的代谢变化提供了关键信号。
