The enzyme phosphoribosyl pyrophosphate synthase (PRPS) catalyzes the conversion of ribose 5-phosphate into phosphoribosyl diphosphate; the latter is a precursor of purine and pyrimidine nucleotides. Here, we investigated the function of PRPS from the single-celled green alga Chlamydomonas reinhardtii in its response to DNA damage from gamma radiation or the alkylating agent LiCl. CrPRPS transcripts were upregulated in cells treated with these agents. We generated CrPRPS-overexpressing transgenic lines to study the function of CrPRPS. When grown in culture with LiCl or exposed to gamma radiation, the transgenic cells grew faster and had a greater survival rate than wild-type cells. CrPRPS overexpression enhanced expression of genes associated with DNA damage response, namely RAD51, RAD1, and LIG1. We observed, from transcriptome analysis, upregulation of genes that code for key enzymes in purine metabolism, namely ribonucleoside-diphosphate pyrophosphokinase subunit M1, adenylate kinase, and nucleoside-diphosphate kinase. We conclude that CrPRPS may affect DNA repair process via regulation of de novo nucleotide synthesis.

中文翻译：

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磷酸核糖焦磷酸合酶的过度表达增强了衣藻对电离辐射的抵抗力。

磷酸核糖焦磷酸合酶 (PRPS) 催化核糖 5-磷酸转化为磷酸核糖二磷酸；后者是嘌呤和嘧啶核苷酸的前体。在这里，我们研究了来自单细胞绿藻莱茵衣藻的 PRPS 在其对伽马辐射或烷化剂 LiCl 造成的 DNA 损伤的反应中的功能。CrPRPS 转录本在用这些试剂处理的细胞中上调。我们生成了 CrPRPS 过表达的转基因品系来研究 CrPRPS 的功能。当与 LiCl 一起培养或暴露于伽马辐射时，转基因细胞比野生型细胞生长得更快，存活率更高。CrPRPS 过表达增强了与 DNA 损伤反应相关的基因的表达，即 RAD51、RAD1 和 LIG1。我们从转录组分析中观察到，上调编码嘌呤代谢关键酶的基因，即核糖核苷二磷酸焦磷酸激酶亚基 M1、腺苷酸激酶和核苷二磷酸激酶。我们得出结论，CrPRPS 可能通过调节从头核苷酸合成来影响 DNA 修复过程。