In biological membranes, various protein secretion devices function as nanomachines, and measuring the internal movements of their component parts is a major technological challenge. The translocation and assembly module (TAM) is a nanomachine required for virulence of bacterial pathogens. We have reconstituted a membrane containing the TAM onto a gold surface for characterization by quartz crystal microbalance with dissipation (QCM-D) and magnetic contrast neutron reflectrometry (MCNR). The MCNR studies provided structural resolution down to 1 A, enabling accurate measurement of protein domains projecting from the membrane layer. Here we show that dynamic movements within the TamA component of the TAM are initiated in the presence of a substrate protein, Ag43, and that these movements recapitulate an initial stage in membrane protein assembly. The reconstituted system provides a powerful new means to study molecular movements in biological membranes, and the technology is widely applicable to studying the dynamics of diverse cellular nanomachines.
, Leyton, D. L., Shiota, T., Belousoff, M. J.
, Noinaj, N., Lu, J., Holt, S. A., Tan, K. S., Selkrig, J. P., Webb, C. T.
, Buchanan, S. K., Martin, L. L., & Lithgow, T. J.
(2014). Reconstitution of a nanomachine driving the assembly of proteins into bacterial outer membranes
. Nature Communications
(5078), 1 - 10. https://doi.org/10.1038/ncomms6078