Kdp-dependent Kplus homeostasis of the halophilic archaeon Halobacterium salinarum

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Title: Kdp-dependent Kplus homeostasis of the halophilic archaeon Halobacterium salinarum
Authors: Strahl, Henrik
Thesis advisor: Prof. Dr. Karlheinz Altendorf
Thesis referee: Prof. Dr. Felicitas Pfeifer
Abstract: Halobacteria balance high external osmolality by the accumulation of almost equimolar amounts of KCl. Thus, steady Kplus supply is a vital prerequisite for life of these extreme halophiles. So far, Kplus was supposed to enter the cell only passively by use of potential-driven uniporters. However, the genome of the extreme halophilic archaeon Halobacterium sp. NRC-1 comprises one single operon containing the genes kdpFABC coding for homologs of the bacterial ATP-driven Kplus uptake system KdpFABC, together with an additional ORF so far annotated as cat3. Deletion of the kdpFABCcat3 genes led to a reduced ability to grow under limiting Kplus concentrations, whereas real-time RT-PCR measurements revealed both high induction rates and a transcriptional regulation of the Kdp system dependent on external Kplus concentration and growth phase. The synthesis of the high-affinity KdpFABC complex enables H. salinarum to grow under extreme potassium-limiting conditions of down to 20 µM Kplus. These results provide the first experimental evidence of ATP-driven Kplus uptake in halobacteria. The current opinion that Kplus homeostasis of H. salinarum is solely mediated via membrane potential-driven Kplus uniporters is obviously only one aspect of a more complex system.
URL: https://repositorium.ub.uni-osnabrueck.de/handle/urn:nbn:de:gbv:700-2007121710
Subject Keywords: Halobacterium; potassium uptake; KdpFABC; Cat3; universal stress protein
Issue Date: 14-Dec-2007
Type of publication: Dissertation oder Habilitation [doctoralThesis]
Appears in Collections:FB05 - E-Dissertationen

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