Show simple item record

dc.contributor.authorBosak, Jan
dc.date.accessioned2014-08-05T13:19:08Z
dc.date.issued2014-08-05
dc.identifier.urihttp://hdl.handle.net/10464/5529
dc.description.abstractDuring infection, the model plant Arabidopsis thaliana is capable of activating long lasting defence responses both in tissue directly affected by the pathogen and in more distal tissue. Systemic acquired resistance (SAR) is a type of systemic defence response deployed against biotrophic pathogens resulting in altered plant gene expression and production of antimicrobial compounds. One such gene involved in plant defence is called pathogenesis-related 1 (PR1) and is under the control of several protein regulators. TGA II-clade transcription factors (namely TGA2) repress PR1 activity prior to infection by forming large oligomeric complexes effectively blocking gene transcription. After pathogen detection, these complexes are dispersed by a mechanism unknown until now and free TGA molecules interact with the non-expressor of pathogenesis-related gene 1 (NPR1) protein forming an activating complex enabling PR1 transcription. This study elucidates the TGA2 dissociation mechanism by introducing protein kinase CK2 into this process. This enzyme efficiently phosphorylates TGA2 resulting in two crucial events. Firstly, the DNA-binding ability of this transcription factor is completely abolished explaining how the large TGA2 complexes are quickly evicted from the PR1 promoter. Secondly, a portion of TGA2 molecules dissociate from the complexes after phosphorylation which likely makes them available for the formation of the TGA2-NPR1 activating complex. We also show that phosphorylation of a multiserine motif found within TGA2’s N terminus is responsible for the change of affinity to DNA, while modification of a single threonine in the leucine zipper domain seems to be responsible for deoligomerization. Despite the substantial changes caused by phosphorylation, TGA2 is still capable of interacting with NPR1 and these proteins together form a complex on DNA promoting PR1 transcription. Therefore, we propose a change in the current model of how PR1 is regulated by adding CK2 which targets TGA2 displacing it’s complexes from the promoter and providing solitary TGA2 molecules for assembly of the activating complex. Amino acid sequences of regions targeted by CK2 in Arabidopsis TGA2 are similar to those found in TGA2 homologs in rice and tobacco. Therefore, the molecular mechanism that we have identified may be conserved among various plants, including important crop species, adding to the significance of our findings.en_US
dc.language.isoengen_US
dc.publisherBrock Universityen_US
dc.subjectTGA2 phosphorylation, protein kinase CK2en_US
dc.titleThe Molecular Consequences of CK2-mediated Phosphorylation of the TGA2 Transcription Factor within Systemic Acquired Resistance of Arabidopsis thalianaen_US
dc.typeElectronic Thesis or Dissertationen_US
dc.degree.namePh.D. Biotechnologyen_US
dc.degree.levelDoctoralen_US
dc.contributor.departmentCentre for Biotechnologyen_US
dc.degree.disciplineFaculty of Mathematics and Scienceen_US
dc.embargo.lift2015-07-31T13:19:08Z
dc.embargo.terms12 Monthsen_US
refterms.dateFOA2021-07-31T01:56:21Z


Files in this item

Thumbnail
Name:
Brock_Bosak_Jan_2014.pdf
Size:
5.191Mb
Format:
PDF

This item appears in the following Collection(s)

Show simple item record