Component Interactions and Electron Transfer in Toluene/o-Xylene Monooxygenase
The multicomponent protein toluene/o-xylene monooxygenase (ToMO) activates molecular oxygen to oxidize aromatic hydrocarbons. Prior to dioxygen activation, two electrons are injected into each of two diiron(III) units of the hydroxylase, a process that involves three redox active proteins: the ToMO...
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| Format: | Article |
| Language: | en_US |
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American Chemical Society (ACS)
2017
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| Online Access: | http://hdl.handle.net/1721.1/109714 https://orcid.org/0000-0002-2693-4982 |
| _version_ | 1826207212008112128 |
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| author | Liang, Alexandria D Lippard, Stephen J. |
| author2 | Massachusetts Institute of Technology. Department of Chemistry |
| author_facet | Massachusetts Institute of Technology. Department of Chemistry Liang, Alexandria D Lippard, Stephen J. |
| author_sort | Liang, Alexandria D |
| collection | MIT |
| description | The multicomponent protein toluene/o-xylene monooxygenase (ToMO) activates molecular oxygen to oxidize aromatic hydrocarbons. Prior to dioxygen activation, two electrons are injected into each of two diiron(III) units of the hydroxylase, a process that involves three redox active proteins: the ToMO hydroxylase (ToMOH), Rieske protein (ToMOC), and an NADH oxidoreductase (ToMOF). In addition to these three proteins, a small regulatory protein is essential for catalysis (ToMOD). Through steady state and pre-steady state kinetics studies, we show that ToMOD attenuates electron transfer from ToMOC to ToMOH in a concentration-dependent manner. At substoichiometric concentrations, ToMOD increases the rate of turnover, which we interpret to be a consequence of opening a pathway for oxygen transport to the catalytic diiron center in ToMOH. Excess ToMOD inhibits steady state catalysis in a manner that depends on ToMOC concentration. Through rapid kinetic assays, we demonstrate that ToMOD attenuates formation of the ToMOC–ToMOH complex. These data, coupled with protein docking studies, support a competitive model in which ToMOD and ToMOC compete for the same binding site on the hydroxylase. These results are discussed in the context of other studies of additional proteins in the superfamily of bacterial multicomponent monooxygenases. |
| first_indexed | 2024-09-23T13:46:07Z |
| format | Article |
| id | mit-1721.1/109714 |
| institution | Massachusetts Institute of Technology |
| language | en_US |
| last_indexed | 2024-09-23T13:46:07Z |
| publishDate | 2017 |
| publisher | American Chemical Society (ACS) |
| record_format | dspace |
| spelling | mit-1721.1/1097142022-09-28T16:03:48Z Component Interactions and Electron Transfer in Toluene/o-Xylene Monooxygenase Liang, Alexandria D Lippard, Stephen J. Massachusetts Institute of Technology. Department of Chemistry Liang, Alexandria D Lippard, Stephen J. The multicomponent protein toluene/o-xylene monooxygenase (ToMO) activates molecular oxygen to oxidize aromatic hydrocarbons. Prior to dioxygen activation, two electrons are injected into each of two diiron(III) units of the hydroxylase, a process that involves three redox active proteins: the ToMO hydroxylase (ToMOH), Rieske protein (ToMOC), and an NADH oxidoreductase (ToMOF). In addition to these three proteins, a small regulatory protein is essential for catalysis (ToMOD). Through steady state and pre-steady state kinetics studies, we show that ToMOD attenuates electron transfer from ToMOC to ToMOH in a concentration-dependent manner. At substoichiometric concentrations, ToMOD increases the rate of turnover, which we interpret to be a consequence of opening a pathway for oxygen transport to the catalytic diiron center in ToMOH. Excess ToMOD inhibits steady state catalysis in a manner that depends on ToMOC concentration. Through rapid kinetic assays, we demonstrate that ToMOD attenuates formation of the ToMOC–ToMOH complex. These data, coupled with protein docking studies, support a competitive model in which ToMOD and ToMOC compete for the same binding site on the hydroxylase. These results are discussed in the context of other studies of additional proteins in the superfamily of bacterial multicomponent monooxygenases. National Institute of General Medical Sciences (U.S.) (5-R01-GM032134) United States. National Institutes of Health (T32GM008334) 2017-06-07T17:52:27Z 2017-06-07T17:52:27Z 2014-11 2014-10 Article http://purl.org/eprint/type/JournalArticle 0006-2960 1520-4995 http://hdl.handle.net/1721.1/109714 Liang, Alexandria Deliz and Lippard, Stephen J. "Component Interactions and Electron Transfer in Toluene/o-Xylene Monooxygenase." Biochemistry 53, no. 47 (2014 November): 7368–7375 © 2014 American Chemical Society https://orcid.org/0000-0002-2693-4982 en_US http://dx.doi.org/10.1021/bi500892n Biochemistry Article is made available in accordance with the publisher's policy and may be subject to US copyright law. Please refer to the publisher's site for terms of use. application/pdf American Chemical Society (ACS) ACS |
| spellingShingle | Liang, Alexandria D Lippard, Stephen J. Component Interactions and Electron Transfer in Toluene/o-Xylene Monooxygenase |
| title | Component Interactions and Electron Transfer in Toluene/o-Xylene Monooxygenase |
| title_full | Component Interactions and Electron Transfer in Toluene/o-Xylene Monooxygenase |
| title_fullStr | Component Interactions and Electron Transfer in Toluene/o-Xylene Monooxygenase |
| title_full_unstemmed | Component Interactions and Electron Transfer in Toluene/o-Xylene Monooxygenase |
| title_short | Component Interactions and Electron Transfer in Toluene/o-Xylene Monooxygenase |
| title_sort | component interactions and electron transfer in toluene o xylene monooxygenase |
| url | http://hdl.handle.net/1721.1/109714 https://orcid.org/0000-0002-2693-4982 |
| work_keys_str_mv | AT liangalexandriad componentinteractionsandelectrontransferintolueneoxylenemonooxygenase AT lippardstephenj componentinteractionsandelectrontransferintolueneoxylenemonooxygenase |