Molecular Mechanisms of Membrane Transport Processes
Co-workers: Vitan Blagotinsek, Marco Mazzorana, Mihaela Smilova
Our research aims at understanding, how the biological function of membrane transport proteins is encoded in their molecular structure. The plasma membrane of all living cells functions as a physico-chemical barrier between the cell cytosol and the “outside world”. Defined concentration gradients across the plasma membrane are constantly generated and maintained by certain classes of membrane transport proteins, while others exploit the energy stored in such gradients for secondary transport processes.
A main focus of the group lies on primary active transport proteins from the P-type ATPase family. P-type ATPases are highly flexible multi-domain transporters that use energy from ATP hydrolysis for the specific transport of ions across cellular membranes. We are particularly interested in the ATPase with the smallest substrate of all, the H+-ATPase – or proton pump.
It pumps single protons across the plasma membrane in plants and fungi and thereby creates the proton-motive force, which is vital for the organism i.e. by fueling vital nutrient uptake systems. In certain fungi, the proton pump forms hexamers of ~600 kDa. Using a variety of state-of-the-art biochemical and biophysical methods, we want to thoroughly characterise the proton transport process and its regulation in vitro, and by determining a high-resolution crystal structure of the proton pump, we aim at understanding the structural basis for the specific and unidirectional transport of protons across the membrane. This research also provides an important framework for the development of novel antifungal medication.
Furthermore, we are interested in the exploration and development of new methods for investigating membrane protein-lipid interactions and determining structures from small and/or poorly diffracting crystals.
Hahn A, Parey K, Bublitz M, Mills DJ, Zickermann V, Vonck J, Kühlbrandt W, Meier T. (2016) Structure of a Complete ATP Synthase Dimer Reveals the Molecular Basis of Inner Mitochondrial Membrane Morphology. Mol Cell [Epub ahead of print] doi: 10.1016/j.molcel.2016.05.037.
Clausen JD*, Bublitz M*, Arnou B, Olesen C, Andersen JP, Møller JV, Nissen P. (2016) Crystal Structure of the Vanadate-Inhibited Ca2+-ATPase. Structure 24(4):617-23.
Karlsen JL, Bublitz M. (2016) How to Compare, Analyze, and Morph Between Crystal Structures of Different Conformations: The P-Type ATPase Example. Methods Mol Biol. 1377:523-39.
Nass K, Foucar L, Barends TR, Hartmann E, Botha S, Shoeman RL, Doak RB, Alonso-Mori R, Aquila A, Bajt S, Barty A, Bean R, Beyerlein KR, Bublitz M, Drachmann N, Gregersen J, Jönsson HO, Kabsch W, Kassemeyer S, Koglin JE, Krumrey M, Mattle D, Messerschmidt M, Nissen P, Reinhard L, Sitsel O, Sokaras D, Williams GJ, Hau-Riege S, Timneanu N, Caleman C, Chapman HN, Boutet S, Schlichting I. (2015) Indications of radiation damage in ferredoxin microcrystals using high-intensity X-FEL beams. J Synchrotron Radiat. 22(Pt 2):225-38.
- Bublitz M, Nass K, Drachmann ND, Markvardsen AJ, Gutmann, MJ, Barends TR, Mattle D, Shoeman RL, Doak RB, Boutet S, Messerschmidt M, Seibert MM, Williams GJ, Foucar L, Reinhard L, Sitsel O, Gregersen JL, Clausen JD, Boesen T, Gotfryd K, Wang KT, Olesen C, Møller JV, Nissen P, Schlichting I. (2015) Structural studies of P-type ATPase ligand complexes using an X-ray free-electron laser. IUCrJ 2(Pt4): 409-20.
Drachmann ND, Olesen C, Møller JV, Guo Z, Nissen P, Bublitz M. (2014) Comparing crystal structures of Ca2+-ATPase in the presence of different lipids. FEBS Journal 281(18): 4249-62.
Penner RC, Andersen ES, Jensen JL, Kantcheva AK, Bublitz M, Nissen P, Rasmussen AM, Svane KL, Hammer B, Rezazadegan R, Nielsen NC, Nielsen JT, Andersen JE. (2014) Hydrogen bond rotations as a uniform structural tool for analyzing protein architecture. Nat Commun. 5:5803
- Montigny C, Decottignies P, Le Maréchal P, Capy P, Bublitz M, Olesen C, Møller JV, Nissen P, le Maire M. (2014) S-palmitoylation and s-oleoylation of rabbit and pig sarcolipin. J Biol Chem. 289(49):33850-61.
Figure 1: Left, Cartoon representation of a P-type ATPase (SERCA1a). Nucleotide-binding (N-) domain in red, Actuator (A-) domain in yellow, Phosphorylation (P-) domain in blue. The transported substrate ions (Ca2+, cyan) are bound within the transmembrane region. Right: generic topology diagram of a P-type ATPase.
Figure 2: Protein crystals (left); diffraction pattern (middle). Electron density map and a molecular protein model, revealing an unexpected network of water molecules in the transmembrane region of SERCA1a (right).
Graduate Student and Postdoctoral Positions: Enquiries with CV welcome