Influence of haem environment on the catalytic properties of the tetrathionate reductase TsdA from Campylobacter jejuni

Kurth, Julia M., Butt, Julea N. ORCID:, Kelly, David J. and Dahl, Christiane (2016) Influence of haem environment on the catalytic properties of the tetrathionate reductase TsdA from Campylobacter jejuni. Bioscience Reports, 36 (6). ISSN 0144-8463

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Bifunctional diheme cytochrome c thiosul­fate dehydrogenases/tetrathionate reductases (TsdA) exhibit different catalytic properties depend­ing on the source organism. In the human food-borne intestinal pathogen Campylobacter jejuni , TsdA functions as a tetrathionate reductase en­abling respiration with tetrathionate as an al­ternative electron acceptor. Here, evidence is provided that Cys138 and Met255 serve as the sixth ligands of Heme 1 and Heme 2, respec­tively, in the oxidized Cj TsdA wt protein. Re­placement of Cys138 resulted in a virtually inac­tive enzyme, confirming Heme 1 as the active site heme. Significantly, TsdA variants carrying amino acid exchanges in the vicinity of the elec­tron-transferring Heme 2 (Met255, Asn254 and Lys252) exhibited markedly altered catalytic properties of the enzyme, showing these residues play a key role in the physiological function of TsdA. The growth phenotypes and tetrathionate reductase activities of a series of Δ tsdA/*tsdA complemen­tation strains constructed in the original host C. jejuni 81116, showed that in vivo , the TsdA variants exhibited the same catalytic properties as the pure, recombinantly produced enzymes. However, variants that catalyzed tetrathionate reduction more effectively than the wild-type enzyme did not allow better growth.

Item Type: Article
Additional Information: Date of Acceptance: 18/10/2016 © 2016 The Author(s). This is an open access article published by Portland Press Limited on behalf of the Biochemical Society and distributed under the Creative Commons Attribution Licence 4.0 (CC BY).
Uncontrolled Keywords: axial heme ligation,reaction directionality,thiosulfate,tetrathionate reductase,cytochrome c
Faculty \ School: Faculty of Science > School of Chemistry
Faculty of Science > School of Biological Sciences
Related URLs:
Depositing User: Pure Connector
Date Deposited: 03 Nov 2016 16:00
Last Modified: 21 Oct 2022 07:32
DOI: 10.1042/BSR20160457

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