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Conformational Disorganization within the Active Site of a Recently Evolved Organophosphate Hydrolase Limits Its Catalytic Efficiency

Mabbitt, Peter; Correy, Galen; Meirelles, Tamara; Fraser, Nicholas; Coote, Michelle; Jackson, Colin

Description

The evolution of new enzymatic activity is rarely observed outside of the laboratory. In the agricultural pest Lucilia cuprina, a naturally occurring mutation (Gly137Asp) in α-esterase 7 (LcαE7) results in acquisition of organophosphate hydrolase activity and confers resistance to organophosphate insecticides. Here, we present an X-ray crystal structure of LcαE7:Gly137Asp that, along with kinetic data, suggests that Asp137 acts as a general base in the new catalytic mechanism. Unexpectedly, the...[Show more]

dc.contributor.authorMabbitt, Peter
dc.contributor.authorCorrey, Galen
dc.contributor.authorMeirelles, Tamara
dc.contributor.authorFraser, Nicholas
dc.contributor.authorCoote, Michelle
dc.contributor.authorJackson, Colin
dc.date.accessioned2020-09-13T23:54:49Z
dc.date.available2020-09-13T23:54:49Z
dc.identifier.issn0006-2960
dc.identifier.urihttp://hdl.handle.net/1885/209991
dc.description.abstractThe evolution of new enzymatic activity is rarely observed outside of the laboratory. In the agricultural pest Lucilia cuprina, a naturally occurring mutation (Gly137Asp) in α-esterase 7 (LcαE7) results in acquisition of organophosphate hydrolase activity and confers resistance to organophosphate insecticides. Here, we present an X-ray crystal structure of LcαE7:Gly137Asp that, along with kinetic data, suggests that Asp137 acts as a general base in the new catalytic mechanism. Unexpectedly, the conformation of Asp137 observed in the crystal structure obstructs the active site and is not catalytically productive. Molecular dynamics simulations reveal that alternative, catalytically competent conformers of Asp137 are sampled on the nanosecond time scale, although these states are less populated. Thus, although the mutation introduces the new reactive group responsible for organophosphate detoxification, the catalytic efficiency appears to be limited by conformational disorganization: the frequent sampling of low-energy nonproductive states. This result is consistent with a model of molecular evolution in which initial function-changing mutations can result in enzymes that display only a fraction of their catalytic potential due to conformational disorganization.
dc.description.sponsorshipThis work was supported by a Defense Threat Reduction Agency Contract HDTRA1-11-C-0047. C.J.J. and M.L.C. were supported by Australian Research Council Future Fellowships. P.D.M. was the recipient of a John Stocker Postdoctoral Fellowship from the Science and Industry Endowment Fund (Australia).
dc.format.mimetypeapplication/pdf
dc.language.isoen_AU
dc.publisherAmerican Chemical Society
dc.rights© 2016 American Chemical Society
dc.sourceBiochemistry
dc.subjectanimals
dc.subjectbinding sites
dc.subjectcatalytic domain
dc.subjectcrystallography, x-ray
dc.subjectinsecta
dc.subjectphosphoric monoester hydrolases
dc.subjectprotein conformation
dc.subjectprotein structure, secondary
dc.subjectprotein structure, tertiary
dc.titleConformational Disorganization within the Active Site of a Recently Evolved Organophosphate Hydrolase Limits Its Catalytic Efficiency
dc.typeJournal article
local.identifier.citationvolume55
dc.date.issued2016-03-08
local.publisher.urlhttp://pubs.acs.org/journal/bichaw
local.type.statusAccepted Version
local.contributor.affiliationMabbitt, P., Research School of Chemistry, The Australian National University
local.contributor.affiliationCorrey, G., Research School of Chemistry, The Australian National University
local.contributor.affiliationMeirelles, T., Research School of Chemistry, The Australian National University
local.contributor.affiliationResearch School of Chemistry, The Australian National University
local.contributor.affiliationResearch School of Chemistry, The Australian National University
local.contributor.affiliationResearch School of Chemistry, The Australian National University
dc.relationhttp://purl.org/au-research/grants/arc/CE140100012
local.identifier.essn1520-4995
local.bibliographicCitation.issue9
local.bibliographicCitation.startpage1408
local.bibliographicCitation.lastpage1417
local.identifier.doi10.1021/acs.biochem.5b01322
dcterms.accessRightsOpen Access
dc.provenancehttps://v2.sherpa.ac.uk/id/publication/7766..."The Accepted Version can be archived in a non-commercial institutional repository if required by funder. 12 months embargo." from SHERPA/RoMEO site (as at 2/09/2020)." This document is the Accepted Manuscript version of a Published Work that appeared in final form in Biochemistry, copyright © American Chemical Society after peer review and technical editing by the publisher. To access the final edited and published work see https://dx.doi.org/10.1021/acs.biochem.5b01322
CollectionsANU Research Publications

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