Welcome to a LINXS seminar with Prof. Christine Ziegler from

Where: LINXS workshop room, 5th floor (Ideon Delta 5, Scheelevägen 19, Lund)
When: Thursday, Feb 27, 15.00 - 16.00 (Coffee is served from 14.45) No registration necessary!

Title: Membrane transport regulation by lipids

Abstract
The Na+-coupled trimeric betaine symporter BetP from Corynebacterium glutamicum counteracts hyperosmotic stress by betaine accumulation up to molar range.  Osmotic stress is sensed by BetP via the 45 amino acids long C-terminal domain. Biochemical data suggested a molecular switch model, in which the positively charged osmo-sensory C-terminal domain is attached to the negatively charged surface of the C. glutamicum inner membrane leaflet. Following a hyperosmotic upshift the C-terminal domain is suggested to detach from the membrane and the transport rate of betaine is up-regulated by 5-10-fold. To date it is still unknown which stimuli are sensed by BetP under hyperosmotic conditions. Although data from six different crystal structures revealed the entire alternating access cycle, the ‘molecular switch’ performed by the C-terminal domain during activation was not known on a molecular level. Recent cryo-EM data in combination with new X-ray structures, HDX, FRET and FTIR measurements provided now new insights into this intriguing regulatory mechanism, which exploits a sophisticated lipid-lipid interaction network to transduce stress signals into an up-regulated transport activity.