This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. Bacteria such as Escherichia coli have developed various mechanisms to overcome toxic environments that are otherwise unfavorable for their survival. One important strategy that bacteria use to subvert toxic compounds, including heavy metal ions, is the expression of membrane transporters that recognize and actively export these toxic compounds out of bacterial cells, thereby allowing the bugs to survive in extremely toxic conditions. Our long-term goal is to elucidate the structures and fundamental mechanisms that give rise to heavy metal ion recognition and extrusion in heavy metal efflux proteins. The primary target of this proposal is the E. coli CusABC efflux system that recognizes and extrudes silver and copper ions out of the bacterial cell. CusA consists of 1,047 amino acid residues. It is an inner membrane transporter, which belongs to the resistance-nodulation-division (RND) protein superfamily. CusC is a 457 amino acid polypeptide that forms an outer membrane channel in E. coli. These two membrane proteins interact with each other, in conjunction with a membrane fusion protein CusB (379 amino acids), to mediate the extrusion of heavy metal ions across both membranes of E. coli. It has been proposed that CusB may act as an adaptor that brings CusA and CusC together to form the CusABC tripartite complex. This efflux complex makes direct contact with the metal ions and selectively expels them out of the cell. We recently cloned, expressed, and purified the full-length CusA, CusC, and CusB efflux proteins. We also crystallized each protein in detergent solution using vapor-diffusion. X-ray diffraction data were collected from cryocooled crystals at a synchrotron light source.
The specific aims are to determine the structural basis of heavy-metal ion interactions with: (1) the CusA inner membrane efflux pump, (2) the CusC outer membrane channel, and (3) the CusB membrane fusion protein.

National Institute of Health (NIH)
National Center for Research Resources (NCRR)
Biotechnology Resource Grants (P41)
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Cornell University
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Fallas, Jorge A; Ueda, George; Sheffler, William et al. (2017) Computational design of self-assembling cyclic protein homo-oligomers. Nat Chem 9:353-360
Krotee, Pascal; Rodriguez, Jose A; Sawaya, Michael R et al. (2017) Atomic structures of fibrillar segments of hIAPP suggest tightly mated ?-sheets are important for cytotoxicity. Elife 6:
Dhayalan, Balamurugan; Mandal, Kalyaneswar; Rege, Nischay et al. (2017) Scope and Limitations of Fmoc Chemistry SPPS-Based Approaches to the Total Synthesis of Insulin Lispro via Ester Insulin. Chemistry 23:1709-1716
Bale, Jacob B; Gonen, Shane; Liu, Yuxi et al. (2016) Accurate design of megadalton-scale two-component icosahedral protein complexes. Science 353:389-94
AhYoung, Andrew P; Koehl, Antoine; Vizcarra, Christina L et al. (2016) Structure of a putative ClpS N-end rule adaptor protein from the malaria pathogen Plasmodium falciparum. Protein Sci 25:689-701
Hancock, Stephen P; Stella, Stefano; Cascio, Duilio et al. (2016) DNA Sequence Determinants Controlling Affinity, Stability and Shape of DNA Complexes Bound by the Nucleoid Protein Fis. PLoS One 11:e0150189
Taylor, Noah D; Garruss, Alexander S; Moretti, Rocco et al. (2016) Engineering an allosteric transcription factor to respond to new ligands. Nat Methods 13:177-83
Kattke, Michele D; Chan, Albert H; Duong, Andrew et al. (2016) Crystal Structure of the Streptomyces coelicolor Sortase E1 Transpeptidase Provides Insight into the Binding Mode of the Novel Class E Sorting Signal. PLoS One 11:e0167763
Jorda, J; Leibly, D J; Thompson, M C et al. (2016) Structure of a novel 13 nm dodecahedral nanocage assembled from a redesigned bacterial microcompartment shell protein. Chem Commun (Camb) 52:5041-4
Dhayalan, Balamurugan; Fitzpatrick, Ann; Mandal, Kalyaneswar et al. (2016) Efficient Total Chemical Synthesis of (13) C=(18) O Isotopomers of Human Insulin for Isotope-Edited FTIR. Chembiochem 17:415-20

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