Abstract：
The complexities of energy transfer mechanisms in the flagella of mammalian sperm flagella have been intensively investigated and demonstrate significant diversity across species. Enzymatic shuttles, particularly adenylate kinase (AK) and creatine kinase (CK), are pivotal in the efficient transfer of intracellular ATP, showing distinct tissue- and species-specificity. Here, the expression profiles of AK and CK were investigated in mice and found to fall into four subgroups, of which Subgroup III AKs were observed to be unique to the male reproductive system and conserved across chordates. Both AK8 and AK9 were found to be indispensable to male reproduction after analysis of an infertile male cohort. Knockout mouse models showed that AK8 and AK9 were central to promoting sperm motility. Immunoprecipitation combined with mass spectrometry revealed that AK8 and AK9 interact with the radial spoke (RS) of the axoneme. Examination of various human and mouse sperm samples with substructural damage, including the presence of multiple RS subunits, showed that the head of radial spoke 3 acts as an adapter for AK9 in the flagellar axoneme. Using an ATP probe together with metabolomic analysis, it was found that AK8 and AK9 cooperatively regulated ATP transfer in the axoneme, and were concentrated at sites associated with energy consumption in the flagellum. These findings indicate a novel function for RS beyond its structural role, namely, the regulation of ATP transfer. In conclusion, the results expand the functional spectrum of AK proteins and suggest a fresh model regarding ATP transfer within mammalian flagella.
摘要：
哺乳动物精子鞭毛鞭毛中能量转移机制的复杂性已得到深入研究，并显示出跨物种的显着多样性。酶穿梭车,特别是腺苷酸激酶（AK）和肌酸激酶（CK），是细胞内ATP有效转移的关键，显示出不同的组织和物种特异性。这里,在小鼠中研究了AK和CK的表达谱，发现分为四个亚组，其中观察到III亚组AK是男性生殖系统特有的，并且在整个脊索中保守。在分析不育男性队列后，发现AK8和AK9对于男性生殖是必不可少的。敲除小鼠模型显示AK8和AK9是促进精子运动的核心。免疫沉淀结合质谱显示，AK8和AK9与轴突的径向辐条（RS）相互作用。检查具有亚结构损伤的各种人类和小鼠精子样本，包括多个RS亚基的存在，表明，径向辐条3的头部充当鞭毛轴突中AK9的适配器。使用ATP探针和代谢组学分析，发现AK8和AK9共同调节轴突内的ATP转移，并集中在鞭毛中与能量消耗相关的部位。这些发现表明RS的新功能超出了其结构作用，即,ATP转移的调节。总之,结果扩展了AK蛋白的功能谱，并提出了有关哺乳动物鞭毛内ATP转移的新模型。
