Premium
Cation specificity of osmosensing by the betaine carrier BetP of Corynebacterium glutamicum
Author(s) -
Schiller Dirk,
Krämer Reinhard,
Morbach Susanne
Publication year - 2004
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/s0014-5793(04)00279-0
Subject(s) - corynebacterium glutamicum , betaine , escherichia coli , chemistry , biochemistry , osmotic shock , osmotic pressure , substrate (aquarium) , phospholipid , biophysics , biology , membrane , gene , ecology
The Na + /betaine carrier BetP from Corynebacterium glutamicum was purified and reconstituted in Escherichia coli phospholipid liposomes and its osmosensory properties were studied with respect to the cation specificity of osmotic activation. To dissect the influence of the co‐substrate Na + on the energetics of uptake from its possible role as a putative trigger of osmolality‐dependent BetP activation, the internal Na + concentration was varied without changing ΔpNa + . Studying betaine uptake at increasing luminal Na + or K + revealed that BetP activity was triggered by Na + only to a negligible extent compared to activation by K + . We conclude that activation of BetP in proteoliposomes depends solely on K + , both in mechanistic and in physiological terms.