The transmembrane domains of the sensor kinase KdpD of Escherichia coli are not essential for sensing K+ limitation

Autor(en): Heermann, R
Fohrmann, A
Altendorf, K 
Jung, K
Stichwörter: Biochemistry & Molecular Biology; KDPABC OPERON; Microbiology; NA+/PROLINE TRANSPORTER; OPERON EXPRESSION; PHOSPHATASE-ACTIVITY; POTASSIUM-TRANSPORT; PROTEIN; RECONSTITUTION; SIGNAL-TRANSDUCTION; SYSTEM; TURGOR SENSOR
Erscheinungsdatum: 2003
Herausgeber: BLACKWELL PUBLISHING LTD
Journal: MOLECULAR MICROBIOLOGY
Volumen: 47
Ausgabe: 3
Startseite: 839
Seitenende: 848
Zusammenfassung: 
The sensor kinase/response regulator system KdpD/KdpE of Escherichia coli regulates the expression of the kdpFABC operon, which encodes the high affinity K+ transport system KdpFABC. The membrane-bound sensor kinase KdpD consists of four transmembrane domains, a large cytoplasmic N-terminal domain and a cytoplasmic C-terminal transmitter domain. To elucidate the role of the four transmembrane domains, various deletions were introduced in kdpD and the activities of the resulting truncated derivatives of KdpD were determined. A KdpD protein lacking all four transmembrane domains was able to sense low K+ concentrations, whereas at higher K+ concentrations kdpFABC expression was constitutive. These and further results with various truncated KdpD proteins lacking distinct parts of the transmembrane domains or derivatives in which a linker peptide or two transmembrane domains of PutP, the Na+/proline transporter of Escherichia coli, replaced the missing part indicated that the transmembrane domains are not essential for sensing of K+ limitation, but may be important for the correct positioning of the large N- and C-terminal cytoplasmic domains to each other.
ISSN: 0950382X
DOI: 10.1046/j.1365-2958.2003.03348.x

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