Transcript Gemeinsames Kolloquium

Molekulare Biophysik
Gemeinsames Kolloquium
Referent:
PD Dr. Dirk Schneider
Universität Freiburg
Thema:
Shaping up membranes
and membrane proteins
In contrast to other bacteria but similar to chloroplasts, cyanobacteria harbor six internal compartments (thylakoid
lumen, thylakoid membrane, cytoplasm, cytoplasmic membrane, periplasm, outer membrane), and all these
compartments appear to harbor a defined subset of proteins. It is, however, still unclear how cyanobacteria sort
proteins into these specific compartments and, thus, how biogenesis and maintenance of specialized subcellular
compartments is organized. How does a cyanobacterial cell "decide" which proteins are translocated into the
thylakoid lumen and which proteins are sorted into the periplasmic space? This "sorting problem" is essentially
completely unresolved yet. I will present and discuss our recent work on protein sorting and thylakoid membrane
biogenesis in cyanobacteria with a special focus on a cyanobacterial chaperone network. In a second part I will talk
about folding, assembly and stability of -helical membrane proteins. Many α-helical membrane proteins form
complexes within membranes and fulfil important cellular functions by e.g. mediating the transfer of energy, of
chemical compounds, or of signals across biological membranes. Unfortunately, the abilities to produce, analyze, and
manipulate membrane proteins lag far behind the field of water-soluble proteins. Our primary goal is to gain deeper
insights into the functional role of individual factors for folding, assembly, and stabilization of membrane proteins. In
doing so, we hope to improve existing tools for characterizing membrane proteins and extend their applicability to
larger membrane proteins. We make a critical assessment of the hierarchical or stepwise nature of membrane protein
folding implied in the Two-Stage folding model, and we are mainly interested in the contributions of individual amino
acids, of amino acid motifs, and of cofactors for folding and assembly of membrane proteins. Our studies entail the
assembly of entire membrane proteins themselves, as well as the association of protein fragments, both in vivo and
in vitro. In particular, we intend to develop a detailed understanding of the energetic contributions of different amino
acid side-chains in helix-helix interactions, as well of the role played by cofactors.
Ort:
HS 18, Zoologie
Johann-Joachim-Becher-Weg 9
Zeit:
Montag, 08.12.2008, 17.15 Uhr
Info:
http://iabserv.biologie.uni-mainz.de/index.php
Biologie