Dynamics of functional membrane complexes associated with the plasma membrane H+-ATPase AHA2

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The plasma membrane is the boundary compartment which enables exchange of substances (nutrients, hormones) between cytosol and the outside environment. Plants must rapidly adjust their cellular status, growth and development and metabolism to changes in the environment. In recent years it became more and more evident that the protein composition of the plasma membrane is highly dynamic and stimulus-dependent. Within the plasma membrane of plants, the H+-ATPases are the most abundant proteins. The H+-ATPases are not only essential for transmembrane solute transport, but can also affect cell elongation, the opening and closing of the stomata and the responses to environmental stress and pathogen attack. Thus, the H+-ATPases are highly regulated, particularly by phosphorylation at several activating and inhibiting sites by different kinases. The recent discovery of short, direct regulatory pathways within the plasma membrane involving receptor kinases regulating proton pumps, water channels and other membrane transporters suggests that this is a modular generic principle allowing plants to very rapidly adjust to changing and challenging environments. We propose that dependent on external conditions, the receptor/coreceptor pairs interacting with the H+-ATPase are variable components of a dynamic complex resulting in conditional interactions and phosphorylation of the H+-ATPase at activating or inhibiting phosphorylation sites.Based on the proposed model of dynamic functional protein complexes within the plasma membrane, we aim at systematically studying how the plasma membrane H+-ATPase AHA2 forms different protein complexes dependent on external stimuli using a combination of proteomics and modern spectro-microscopic methods. Thereby, we are particularly interested in the receptor kinase / co-receptor pairs dynamically recruited into these functional complexes of AHA2