Department of Zoology, University of Delhi, Delhi, India.
CSIR-Institute of Genomics and Integrative Biology, Mall Road, Delhi, India.
PLoS Pathog. 2022 Aug 1;18(8):e1010729. doi: 10.1371/journal.ppat.1010729. eCollection 2022 Aug.
Reversible protein phosphorylation at serine/threonine residues is one of the most common protein modifications, widely observed in all kingdoms of life. The catalysts controlling this modification are specific serine/threonine kinases and phosphatases that modulate various cellular pathways ranging from growth to cellular death. Genome sequencing and various omics studies have led to the identification of numerous serine/threonine kinases and cognate phosphatases, yet the physiological relevance of many of these proteins remain enigmatic. In Bacillus anthracis, only one ser/thr phosphatase, PrpC, has been functionally characterized; it was reported to be non-essential for bacterial growth and survival. In the present study, we characterized another ser/thr phosphatase (PrpN) of B. anthracis by various structural and functional approaches. To examine its physiological relevance in B. anthracis, a null mutant strain of prpN was generated and shown to have defects in sporulation and reduced synthesis of toxins (PA and LF) and the toxin activator protein AtxA. We also identified CodY, a global transcriptional regulator, as a target of PrpN and ser/thr kinase PrkC. CodY phosphorylation strongly controlled its binding to the promoter region of atxA, as shown using phosphomimetic and phosphoablative mutants. In nutshell, the present study reports phosphorylation-mediated regulation of CodY activity in the context of anthrax toxin synthesis in B. anthracis by a previously uncharacterized ser/thr protein phosphatase-PrpN.
丝氨酸/苏氨酸残基的可逆蛋白磷酸化是最常见的蛋白修饰之一，广泛存在于所有生命领域。控制这种修饰的催化剂是特定的丝氨酸/苏氨酸激酶和磷酸酶，它们调节从生长到细胞死亡的各种细胞途径。基因组测序和各种组学研究已经鉴定出许多丝氨酸/苏氨酸激酶和同源磷酸酶，但这些蛋白质中的许多生理相关性仍然是个谜。在炭疽杆菌中，只有一种丝氨酸/苏氨酸磷酸酶 PrpC 被功能表征；据报道，它对细菌的生长和存活不是必需的。在本研究中，我们通过各种结构和功能方法对炭疽杆菌中的另一种丝氨酸/苏氨酸磷酸酶（PrpN）进行了表征。为了研究其在炭疽杆菌中的生理相关性，我们生成了 prpN 的缺失突变株，并显示其在孢子形成和毒素（PA 和 LF）以及毒素激活蛋白 AtxA 的合成方面存在缺陷。我们还鉴定了 CodY，一种全局转录调节剂，作为 PrpN 和丝氨酸/苏氨酸激酶 PrkC 的靶标。如使用磷酸模拟和磷酸缺失突变体所示，CodY 的磷酸化强烈控制其与 atxA 启动子区域的结合。简而言之，本研究报告了在炭疽杆菌的炭疽毒素合成中，一种以前未被表征的丝氨酸/苏氨酸蛋白磷酸酶 PrpN 通过磷酸化介导 CodY 活性的调节。
