Detection of structural and functional asymmetries in P-glycoprotein by combining mutagenesis and H/D exchange...

During the last few years, Attenuated Total Reflection Fourier Transform Infrared spectroscopy (ATR-FTIR) has become one of the most powerful methods to determine the structure of biological materials and in particular of components of biological membranes, like proteins which cannot be studied by X-ray crystallography and NMR. Indeed, ATR-FTIR method requires little amount of material, gives valuable information about the secondary structure, orientation and tertiary structure changes in peptides and proteins. Moreover, this technique can be used in the presence of lipids and hence provides an excellent tool to study membrane proteins in their natural environment. In this review, we describe how structural information about the catalytic cycle of membrane proteins can be gained by combining ATR-FTIR spectroscopy and mutagenesis. In particular, results obtained about the structure and function of the nucleotide binding domains (NBD) of P-glycoprotein (Pgp), a multidrug transporter involved in cancer cells resistance to chemotherapy, are described.