Structure and function of the bacterial heterodimeric ABC transporter CydDC: stimulation of ATPase activity by thiol and heme compounds

Yamashita, M. and Shepherd, M. and Booth, W. I. and Xie, H. and Postis, V. and Nyathi, Y. and Tzokov, S. B. and Poole, R. K. and Baldwin, S. A. and Bullough, P. A. (2014) Structure and function of the bacterial heterodimeric ABC transporter CydDC: stimulation of ATPase activity by thiol and heme compounds. Journal of Biological Chemistry, 289 (33). pp. 23177-23188. ISSN 0021-9258

Full content URL: http://dx.doi.org/10.1074/jbc.M114.590414

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Abstract

In Escherichia coli, the biogenesis of both cytochrome bd-type quinol oxidases and periplasmic cytochromes requires the ATP-binding cassette-type cysteine/GSH transporter, CydDC. Recombinant CydDC was purified as a heterodimer and found to be an active ATPase both in soluble form with detergent and when reconstituted into a lipid environment. Two-dimensional crystals of CydDC were analyzed by electron cryomicroscopy, and the protein was shown to be made up of two non-identical domains corresponding to the putative CydD and CydC subunits, with dimensions characteristic of other ATP-binding cassette transporters. CydDC binds heme b. Detergent-solubilized CydDC appears to adopt at least two structural states, each associated with a characteristic level of bound heme. The purified protein in detergent showed a weak basal ATPase activity (approximately 100 nmol Pi/min/mg) that was stimulated ∼3-fold by various thiol compounds, suggesting that CydDC could act as a thiol transporter. The presence of heme (either intrinsic or added in the form of hemin) led to a further enhancement of thiol-stimulated ATPase activity, although a large excess of heme inhibited activity. Similar responses of the ATPase activity were observed with CydDC reconstituted into E. coli lipids. These results suggest that heme may have a regulatory role in CydDC-mediated transmembrane thiol transport.

Keywords:ABC Transporter, Bacterial Metabolism, Membrane Protein, Membrane Transporter Reconstitution, Microbiology, Protein Structure, Structural Biology, Transporter, JCOpen
Subjects:C Biological Sciences > C700 Molecular Biology, Biophysics and Biochemistry
Divisions:College of Science > School of Life Sciences
ID Code:27683
Deposited On:20 Jun 2017 16:37

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