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Comparison of the kinetic parameters of alternative oxidases from Trypanosoma brucei and Arabidopsis thaliana-a tale of two cavities
journal contribution
posted on 2023-06-26, 07:15 authored by Fei Xu, Alice CopseyAlice Copsey, Luke Young, Mario R O Barsottini, Mary S Albury, Anthony L MooreThe alternative oxidase (AOX) is widespread in plants, fungi, and some protozoa. While the general structure of the AOX remains consistent, its overall activity, sources of kinetic activation and their sensitivity to inhibitors varies between species. In this study, the recombinant Trypanosoma brucei AOX (rTAO) and Arabidopsis thaliana AOX1A (rAtAOX1A) were expressed in the Escherichia coli ?hemA mutant FN102, and the kinetic parameters of purified AOXs were compared. Results showed that rTAO possessed the highest V max and K m for quinol-1, while much lower V max and K m were observed in the rAtAOX1A. The catalytic efficiency (k cat/K m) of rTAO was higher than that of rAtAOX1A. The rTAO also displayed a higher oxygen affinity compared to rAtAOX1A. It should be noted that rAtAOX1a was sensitive to a-keto acids while rTAO was not. Nevertheless, only pyruvate and glyoxylate can fully activate Arabidopsis AOX. In addition, rTAO and rAtAOX1A showed different sensitivity to AOX inhibitors, with ascofuranone (AF) being the best inhibitor against rTAO, while colletochlorin B (CB) appeared to be the most effective inhibitor against rAtAOX1A. Octylgallate (OG) and salicylhydroxamic acid (SHAM) are less effective than the other inhibitors against protist and plant AOX. A Caver analysis indicated that the rTAO and rAtAOX1A differ with respect to the mixture of polar residues lining the hydrophobic cavity, which may account for the observed difference in kinetic and inhibitor sensitivities. The data obtained in this study are not only beneficial for our understanding of the variation in the kinetics of AOX within protozoa and plants but also contribute to the guidance for the future development of phytopathogenic fungicides.
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Publication status
- Published
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- Published version
Journal
Frontiers in Plant ScienceISSN
1664-462XPublisher
Frontiers MediaPublisher URL
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12Page range
Jan-14Article number
a744218Event location
SwitzerlandDepartment affiliated with
- Biochemistry Publications
Full text available
- Yes
Peer reviewed?
- Yes
Legacy Posted Date
2021-08-04First Open Access (FOA) Date
2021-08-04First Compliant Deposit (FCD) Date
2021-08-04Usage metrics
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