The Kdp-ATPase system and its regulation
The Kdp-ATPase system and its regulation
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DOI：
10.1007/s12038-007-0055-7
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发表时间：
2007-04-01
影响因子：
2.9
通讯作者：
Apte, Siiree Kumar
中科院分区：
文献类型：
--
作者：
Ballal, Anand;Basu, Bhakti;Apte, Siiree Kumar
K+，占主导地位的细胞内阳离子，是必需的各种生理过程，如膨压稳态，pH调节等细菌细胞已经进化出许多不同的K+转运蛋白，以保持所需的浓度的内部K+。在大肠在大肠杆菌中，由kdpFABC操纵子编码的KdpATP酶（由KdpFABC复合物组成）是一种诱导型高亲和力K+转运蛋白，在严重K+限制或渗透压升高的条件下合成。急诊大肠杆菌Up蛋白的表达受KdpD和KdpE蛋白的转录调控，它们共同构成了典型的细菌双组分信号转导系统。Up系统广泛分布在不同种类的细菌中，包括蓝细菌。kdpA、kdpB和kdpC的顺序相对固定，但kdpD/E基因在远亲细菌中显示出不同的排列。我们的研究表明，鱼腥藻L-31具有两个Up操纵子kdp 1和kdp 2，其中kdp 2在缺钾和干燥条件下表达。在调控基因中，鱼腥藻L-31的kdpD ORF与其他细菌的kdpD相比被截短，而kdpE样基因缺失。极端抗辐射细菌，耐辐射异常球菌菌株R1，也显示出在其Up操纵子中存在类似于鱼腥藻的天然短kdpD ORF。综述阐述了细菌UP操纵子在各种环境胁迫条件下的表达，特别强调鱼腥藻。本文还讨论了鱼腥藻和异常球菌独特的kdp操纵子的可能调控机制。
K+, the dominant intracellular cation, is required for various physiological processes like turgor homeostasis, pH regulation etc. Bacterial cells have evolved many diverse K+ transporters to maintain the desired concentration of internal K+. In E. coli, the KdpATPase (comprising of the KdpFABC complex), encoded by the kdpFABC operon, is an inducible high-affinity K+ transporter that is synthesised under conditions of severe K+ limitation or osmotic upshift. The E. coli Up expression is transcriptionally regulated by the KdpD and KdpE proteins, which together constitute a typical bacterial two-component signal transduction system. The Up system is widely dispersed among the different classes of bacteria including the cyanobacteria. The ordering of the kdpA, kdpB and kdpC is relatively fixed but the kdpD/E genes show different arrangements in distantly related bacteria. Our studies have shown that the cyanobacterium Anabaena sp. strain L-31 possesses two Up operons, kdp1 and kdp2, of which, the later is expressed under K+ deficiency and desiccation. Among the regulatory genes, the kdpD ORF of Anabaena L-31 is truncated when compared to the kdpD of other bacteria, while a kdpE-like gene is absent. The extremely radio-resistant bacterium, Deinococcus radiodurans strain R1, also shows the presence of a naturally short kdpD ORF similar to Anabaena in its Up operon. The review elaborates the expression of bacterial Up operons in response to various environmental stress conditions, with special emphasis on Anabaena. The possible mechanism(s) of regulation of the unique kdp operons from Anabaena and Deinococcus are also discussed.