【摘要】 早期生命可能是以焦磷酸(PPi)而不是三磷酸腺苷(ATP)为能源。位于生物膜上偶联PPi水解和质子(H+)跨膜转运的H+-焦磷酸酶(PPase)在原核生物、植物和原生动物中早已广被人知和大量研究。近期则发现了两种与之进化相关且在原核生物中广泛分布的、分别具有Na+泵和Na+,H+泵功能的膜整合Na+-PPase和Na+,H+-PPase,它们水解PPi需要Na+参与并被K+激活。另外,越来越多的研究逐步揭示出膜PPase中决定阳离子转运特异性的主要因子,而且最近对H+-PPase和Na+-PPase的三维结构解析也是膜离子泵结构生物学上的重大突破。本文主要以原核生物Na+-PPase和Na+,H+-PPase为重心综述了目前对膜PPase的结构、转运机制、进化和生物学意义等几方面的研究情况,并对其在创建转基因抗逆物种中的应用前景进行了展望。更多还原

【Abstract】 The early life appeared to utilize pyrophosphate(PPi) rather than adenosine triphosphate(ATP) as the energy source. Membrane-integral H+-pyrophosphatases(PPases) that couple PPi hydrolysis to H+transmembrane transport have long been known with many studies in prokaryotes, plants, and protists. Recently, two evolutionarily related analogues widely distributed in prokaryotic domains have been identified, which can pump Na+(Na+-PPase)or both Na+and H+(Na+,H+-PPase), respectively. Both these cation transporters require Na+for PPi hydrolysis and are further activated by K+. In addition, an increasing number of studies have gradually revealed the major determinants of the cation specificities of membrane PPases, and the recent determination of the three dimensional structures of H+- and Na+-PPases has been the new breakthrough in the structural biology of membrane ion pumps.This overview summarized the current studies on the membrane PPases in terms of structure, transport mechanism,evolution and biological roles, with an emphasis on prokaryotic Na+-PPase and Na+,H+-PPase. Meanwhile, their exploitation to construct stress-resistant transgenic organisms was also prospected.更多还原