Crystallographic Analysis of the CusBA Heavy-Metal Efflux Complex of Escherichia coli

Crystallization is one of the most successful techniques used to determine protein structure, especially for membrane proteins. However, the application of this technique is not straightforward and often hampered by the difficulties associated with expression, purification, and crystallization. Here we present our protocol and methodology for crystallizing the CusBA adaptor-transporter complex of Escherichia coli. Using these procedures, we were able to produce the first co-crystal structure of a resistance-nodulation-cell division (RND) transporter in complex with its associated membrane fusion protein.