ABC Transporters: A Smart Example of Molecular Machineries
Thorsten Jumpertz, I. Barry Holland and Lutz Schmitt
from: ABC Transporters in Microorganisms: Research, Innovation and Value as Targets against Drug Resistance (Edited by: Alicia Ponte-Sucre). Caister Academic Press, U.K. (2009)
ABC transporters are fascinating molecular machines that use the energy of ATP to catalyze the transport of a tremendous variety of substrates across biological membranes in a vectorial fashion. Here, we will summarize our current knowledge of the domain organization and topology of this class of primary transporters. All ABC transporters analyzed so far are composed of two nucleotide-binding domains (NBD) and two transmembrane domains (TMD) that can be arranged in any possible combination. However, additional transmembrane segments or extended NBDs, raise the possibility that these extensions act as platforms to interact with additional proteins with functional or regulatory consequences. In the light of the recent crystal structures of isolated NBDs in different functional states and the structures of intact ABC transporters, we will also focus on the three-dimensional architecture, domain-domain interactions and putative signaling pathways in these membrane proteins that guarantee efficient substrate recognition and translocation in an ATP-dependent manner read more ...