Structure and Function of Secondary Transporters

The project involves three aspects related to secondary transporters,

• structure/function relationships of secondary transporter proteins
• the function of the transporters in the physiology of the organism
• bioinformatics & membrane proteins

• bacterial V-type ATPases

The emphasis in the studies of the molecular properties is on membrane topology, membrane insertion and binding site characteristics of the transporters. The proteins that are being studied belong to two families, the 2-hydroxy-carboxylate transporter (2HCT) family and the glutamate transporter family.

The two main topics on the involvement of secondary transporters in physiological processes are secondary proton motive generation in lactic acid bacteria and regulation of citrate metabolism in B. subtilis. The first topic involves a special group of membrane potential generating transporters and the second an Mg2+ transporting citrate transporter.

Database wide searches of membrane proteins combined with hydropathy profile analysis is used to classify membrane proteins in structural classes.

V-type ATPases are found in the endomembranes of eukaryotic cells and are closely related to F-type ATPases. The latter represent molecular motors that translocate ions across the membrane coupled to the hydrolysis/synthesis of ATP. They are central in energy metabolism of the cell. In the bacterial kingdom, F-type ATPases are common, while V-type ATPases are quite rare. In collaboration with Dr. E.J. boekema of the Biophysical Chemisry department we study the V-type ATPase of the thermophile Caloramator fervidus.