Jafri Raza Ali, Raj Yash, D'Souza Jacinta S
School of Biological Sciences, University of Mumbai-Department of Atomic Energy Centre for Excellence in Basic Sciences, Mumbai, India.
Cell Biochem Biophys. 2025 Jul 18. doi: 10.1007/s12013-025-01825-z.
Adenylate kinases (ADK) maintain cellular energy homeostasis and catalyse a reversible reaction that converts two molecules of ADP into ATP and AMP. ATP in Chlamydomonas reinhardtii flagella is utilised by dynein to generate flagellar beating. ATP must be constantly supplied and maintained; however, the constricted nature of flagella restricts the localisation of mitochondria in vicinity. We show that C. reinhardtii flagella carry conserved ADK domain-containing proteins that are large in number and longer than their cytosolic counterparts. Six of the eight flagellar ADKs are enriched in the central pair apparatus (CPA). Upon flagellar regeneration and resorption, the ADK activity changes, suggesting a shift in the energy demands for the two processes. The total ADK activity in regenerating flagella increased, and resorbing flagella showed an equal but reverse effect. ADKs help regenerate ATP locally and act as phosphotransfer agents that spatially direct the transfer of nucleotides. The ADP to ATP ratio during reflagellation and resorption suggests a role for ADKs in maintaining the nucleotide levels. To the best of our knowledge, this is the first study providing evidence for the role of ADK domain-containing proteins in maintaining ATP homeostasis in response to flagella regeneration and resorption.
腺苷酸激酶（ADK）维持细胞能量稳态，并催化一个可逆反应，将两分子ADP转化为ATP和AMP。莱茵衣藻鞭毛中的ATP被动力蛋白用于产生鞭毛摆动。ATP必须持续供应和维持；然而，鞭毛的狭窄性质限制了线粒体在其附近的定位。我们发现莱茵衣藻鞭毛携带大量含有保守ADK结构域的蛋白质，且这些蛋白质比其胞质对应物更长。八个鞭毛ADK中的六个在中央微管对（CPA）中富集。在鞭毛再生和吸收过程中，ADK活性发生变化，表明这两个过程的能量需求发生了转变。再生鞭毛中的总ADK活性增加，吸收鞭毛则表现出相反但程度相同的效果。ADK有助于在局部再生ATP，并作为磷酸转移剂在空间上指导核苷酸的转移。鞭毛再生和吸收过程中的ADP与ATP比值表明ADK在维持核苷酸水平方面发挥作用。据我们所知，这是第一项为含有ADK结构域的蛋白质在响应鞭毛再生和吸收时维持ATP稳态中的作用提供证据的研究。
