Ammonium Transport Proteins
Our group focuses on understanding the mechanisms that regulate the function of membrane proteins at a molecular level.
Most of the proteins we are investigating belong to the ubiquitous Ammonium Transport (Amt) family of integral membrane proteins.
From Prokaryotes to Plants, these proteins supply nitrogen to the cell in its bio-available form (NH4+ or NH3), which is required for the synthesis of molecules such as amino acids or nucleic acids. Their homologous in mamals are the Rhesus proteins, from which the most prominent member is the Rhesus protein complex from erythrocytes that determines our blood type. Also present in kidney and liver, Rhesus proteins in these tissues are fundamentally involved in acid/basic homeostasis.
The precise mechanism(s) of transport for the Amt family remains, however, unclear.
We determined the high-resolution crystal structure (1.45 Å) of an archaeal Amt protein (PDB code 2B2F), in various ammonium (2B2H) or methylammonium (2B2I) -containing soak solutions and Xe-soak (2B2J), by X-ray crystallography. To clarify the transport mechanism of this family of proteins, we take a multidisciplinary approach using, in combination with such structural studies, molecular biology, biochemistry, modeling and in vitro transport assays with protein reconstituted into artificial lipid bilayers (proteoliposomes).