CAJ | 학술논문

K＋/H＋逆向转运是普遍存在于几乎所有生物体内的重要离子平衡机制之一。该机制主要由多基因家族KEA（K efflux antiporter）介导。然而,长期以来对KEA的功能特征和生理意义的认识,除了在大肠杆菌中有零星的报道之外,绝大部分尚为空白。本文通过生物信息学分析,比较了7个植物物种KEA的同源和进化关系,发现KEA家族中的部分成员在物种进化过程中具有极高的保守性。以模式植物拟南芥为例,进一步研究了KEA的蛋白质跨膜结构、关键结构域和亚细胞定位预测等。结果表明,AtKEA大多具有10～12个跨膜结构,是典型的膜蛋白,在跨膜区的N端有多个丝氨酸磷酸化调控位点;都含有K＋/H＋交换结构域和相应的调控域,推测其能够介导K＋/H＋交换。基因芯片研究表明,AtKEA在根、茎、叶、花和荚果等不同组织器官的表达丰度不同,表明KEA基因家族各成员的生理功能具有时空分异性。上述结果可为进一步深入研究植物K＋/H＋逆向转运系统的功能提供借鉴。
K＋/H＋역향전운시보편존재우궤호소유생물체내적중요리자평형궤제지일。해궤제주요유다기인가족KEA（K efflux antiporter）개도。연이,장기이래대KEA적공능특정화생리의의적인식,제료재대장간균중유령성적보도지외,절대부분상위공백。본문통과생물신식학분석,비교료7개식물물충KEA적동원화진화관계,발현KEA가족중적부분성원재물충진화과정중구유겁고적보수성。이모식식물의남개위례,진일보연구료KEA적단백질과막결구、관건결구역화아세포정위예측등。결과표명,AtKEA대다구유10～12개과막결구,시전형적막단백,재과막구적N단유다개사안산린산화조공위점;도함유K＋/H＋교환결구역화상응적조공역,추측기능구개도K＋/H＋교환。기인심편연구표명,AtKEA재근、경、협、화화협과등불동조직기관적표체봉도불동,표명KEA기인가족각성원적생리공능구유시공분이성。상술결과가위진일보심입연구식물K＋/H＋역향전운계통적공능제공차감。
K＋/H＋ antiporting is employed by almost all living organisms as an important mechanism of ion homeostasis.This machinery is composed of a multi-gene family known as KEA（K efflux antiporter）.However,except a couple of reports from E.coli,the functionalities of most KEAs and their physiological significances remain largely unclear.In this report,homologous comparison of KEAs from seven plant species which had been accomplished in full genome sequencing had revealed members of the KEA family were highly conserved along evolution.Further analyses engaged the KEAs of the model plant Arabidopsis thaliana in regard of their transmembrane structure,putative functional hallmarks as well as predicted subcellular localizations.The results indicated that AtKEAs were membrane proteins and contained 10 to 12 transmembrane domains（TM）,on which locating multiple serine phosphorylation sites to the N-termini of the TMs.Morever,KEAs harbor structurally,a putative K＋/H＋ exchange motif as well as related regulation components,which was in support of a functional deduction as K＋/H＋ antiporters.Results from microarrays indicated that expression of AtKEA genes varied in tissues/organs and developmental stages,suggesting a temporal and spatial pattern of their physiological roles.This report would be expected to provide useful inspiration toward discovery of the functionality of plant K＋/H＋ antiport system.