Show simple item record

dc.contributor.authorMacaulay, KMen
dc.contributor.authorHeath, GAen
dc.contributor.authorCiulli, Aen
dc.contributor.authorMurphy, Alexandraen
dc.contributor.authorAbell, Chrisen
dc.contributor.authorCarr, Johnen
dc.contributor.authorSmith, Alisonen
dc.date.accessioned2017-05-18T13:22:07Z
dc.date.available2017-05-18T13:22:07Z
dc.date.issued2017-04-28en
dc.identifier.issn0264-6021
dc.identifier.urihttps://www.repository.cam.ac.uk/handle/1810/264301
dc.description.abstractThe important plant hormone salicylic acid (SA; 2-hydroxybenzoic acid) regulates several key plant responses including, most notably, defence against pathogens. A key enzyme for SA biosynthesis is isochorismate synthase (ICS), which converts chorismate into isochorismate, and for which there are two genes in $\textit{Arabidopsis thaliana}$ One ($\textit{AtICS1}$) has been shown to be required for increased SA biosynthesis in response to pathogens and its expression can be stimulated throughout the leaf by virus infection and exogenous SA. The other ($\textit{AtICS2}$) appears to be expressed constitutively, predominantly in the plant vasculature. Here, we characterise the enzymatic activity of both isozymes expressed as hexahistidine fusion proteins in $\textit{Escherichia coli}$. We show for the first time that recombinant AtICS2 is enzymatically active. Both isozymes are Mg$^{2+}$-dependent with similar temperature optima (ca. 33°C) and similar K$_{m}$ values for chorismate of 34.3 ± 3.7 and 28.8 ± 6.9 µM for ICS1 and ICS2, respectively, but reaction rates were greater for ICS1 than for ICS2, with respective values for V$_{max}$ of 63.5 ± 2.4 and 28.3 ± 2.0 nM s$^{-1}$ and for k$_{cat}$ of 38.1 ± 1.5 and 17.0 ± 1.2 min$^{-1}$ However, neither enzyme displayed isochorismate pyruvate lyase (IPL) activity, which would enable these proteins to act as bifunctional SA synthases, i.e. to convert chorismate into SA. These results show that although $\textit{Arabidopsis}$ has two functional ICS enzymes, it must possess one or more IPL enzymes to complete biosynthesis of SA starting from chorismate.
dc.description.sponsorshipK.M.M. was supported by a studentship from the Biotechnology and Biological Sciences Research Council (BBSRC). The research was also supported by BBSRC grants [BB/D008204/1, BB/D014376/1 and B/J011762/1], The Leverhulme Trust [grants F/09 741/F and RPG-2012-667], Cambridge University Isaac Newton Trust [Grant 12.07(1)] and Homerton College for a Junior Research Fellowship to A.C. Work in the J.P.C. laboratory had additional support from the Rural Development Agency, Republic of Korea [grant PJ012426].
dc.languageengen
dc.language.isoenen
dc.publisherPortland Press
dc.rightsAttribution 4.0 Internationalen
dc.rightsAttribution 4.0 Internationalen
dc.rightsAttribution 4.0 Internationalen
dc.rightsAttribution 4.0 Internationalen
dc.rights.urihttp://creativecommons.org/licenses/by/4.0/en
dc.rights.urihttp://creativecommons.org/licenses/by/4.0/en
dc.rights.urihttp://creativecommons.org/licenses/by/4.0/en
dc.rights.urihttp://creativecommons.org/licenses/by/4.0/en
dc.subjectchloroplastsen
dc.subjectplant hormonesen
dc.subjectsalicylic aciden
dc.titleThe biochemical properties of the two $\textit{Arabidopsis thaliana}$ isochorismate synthases.en
dc.typeArticle
prism.endingPage1590
prism.issueIdentifier10en
prism.publicationDate2017en
prism.publicationNameBiochemical Journalen
prism.startingPage1579
prism.volume474en
dc.identifier.doi10.17863/CAM.9738
dcterms.dateAccepted2017-03-28en
rioxxterms.versionofrecord10.1042/BCJ20161069en
rioxxterms.versionVoRen
rioxxterms.licenseref.urihttp://creativecommons.org/licenses/by/4.0/en
rioxxterms.licenseref.startdate2017-04-28en
dc.contributor.orcidMurphy, Alexandra [0000-0002-2226-8759]
dc.contributor.orcidAbell, Chris [0000-0001-9174-1987]
dc.contributor.orcidCarr, John [0000-0002-5028-2160]
dc.contributor.orcidSmith, Alison [0000-0001-6511-5704]
dc.identifier.eissn1470-8728
rioxxterms.typeJournal Article/Reviewen
pubs.funder-project-idBBSRC (BB/D008204/1)
pubs.funder-project-idBBSRC (BB/J011762/1)
pubs.funder-project-idBBSRC (BB/F014376/1)
cam.issuedOnline2017-03-29en


Files in this item

Thumbnail

This item appears in the following Collection(s)

Show simple item record

Attribution 4.0 International
Except where otherwise noted, this item's licence is described as Attribution 4.0 International