crystal structure of escherichia coli cusc, the outer membrane component of a heavy metal efflux pump大肠杆菌cusc晶体结构,外膜组件的重金属射流泵.pdfVIP

Crystal Structure of Escherichia coli CusC, the Outer Membrane Component of a Heavy Metal Efflux Pump . . Rithika Kulathila , Ragini Kulathila , Mridhu Indic, Bert van den Berg* University of Massachusetts Medical School, Program in Molecular Medicine, Worcester, Massachusetts, United States of America Abstract Background: While copper has essential functions as an enzymatic co-factor, excess copper ions are toxic for cells, necessitating mechanisms for regulating its levels. The cusCBFA operon of E. coli encodes a four-component efflux pump dedicated to the extrusion of Cu(I) and Ag(I) ions. Methodology/Principal Findings: We have solved the X-ray crystal structure of CusC, the outer membrane component of ˚ the Cus heavy metal efflux pump, to 2.3 A resolution. The structure has the largest extracellular opening of any outer membrane factor (OMF) protein and suggests, for the first time, the presence of a tri-acylated N-terminal lipid anchor. Conclusions/Significance: The CusC protein does not have any obvious features that would make it specific for metal ions, suggesting that the narrow substrate specificity of the pump is provided by other components of the pump, most likely by the inner membrane component CusA. Citation: Kulathila R, Kulathila R, Indic M, van den Berg B (2011) Crystal Structure of Escherichia coli CusC, the Outer Membrane Component of a Heavy Metal Efflux Pump. PLoS ONE 6(1): e15610. doi:10.1371/journal.pone.0015610 Editor: Hendrik W. van Veen, University of Cambridge, United Kingdom Received September 9, 2010; Accepted November 17, 2010; Published January 7, 2011 Copyright: 2011 Kulathila et al. This is an open-access article distributed under the terms of the