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Schlagwörter:
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Zusammenfassung:
The gram-positive soil bacterium Corynebacterium glutamicum, a major amino acid-producing microorganism
in biotechnology, is equipped with several osmoregulated uptake systems for compatible solutes, which is
relevant for the physiological response to osmotic stress. The most significant carrier, BetP, is instantly
activated in response to an increasing cytoplasmic K concentration. Importantly, it is also activated by chill
stress independent of osmotic stress. We show that the activation of BetP by both osmotic stress and chill stress
is altered in C. glutamicum cells grown at and adapted to low temperatures. BetP from cold-adapted cells is less
sensitive to osmotic stress. In order to become susceptible for chill activation, cold-adapted cells in addition
needed a certain amount of osmotic stimulation, indicating that there is cross talk of these two types of stimuli
at the level of BetP activity. We further correlated the change in BetP regulation properties in cells grown at
different temperatures to changes in the lipid composition of the plasma membrane. For this purpose, the
glycerophospholipidome of C. glutamicum grown at different temperatures was analyzed by mass spectrometry
using quantitative multiple precursor ion scanning. The molecular composition of glycerophospholipids was
strongly affected by the growth temperature. The modulating influence of membrane lipid composition on BetP
function was further corroborated by studying the influence of artificial modulation of membrane dynamics by
local anesthetics and the lack of a possible influence of internally accumulated betaine on BetP activity.
