Yes / 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. / This work was supported by Biotechnology and Biological Sciences Research Council grant BBS/B/14418 (Membrane Protein Structure Initiative).
| Identifer | oai:union.ndltd.org:BRADFORD/oai:bradscholars.brad.ac.uk:10454/17911 |
| Date | 10 June 2020 |
| Creators | Yamashita, M., Shepherd, M., Booth, W.I., Xie, H., Postis, V., Nyathi, Yvonne, Tzokov, S.B., Poole, R.K., Baldwin, S.A., Bullough, P.A. |
| Source Sets | Bradford Scholars |
| Language | English |
| Detected Language | English |
| Type | Article, Published version |
| Rights | © 2014 by The American Society for Biochemistry and Molecular Biology, Inc. Creative Commons Attribution Unported License (https://creativecommons.org/licenses/by/3.0/) |
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