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dc.contributor.authorLópez Hernández, Federico
dc.date.accessioned2018-05-30T13:08:17Z
dc.date.available2018-05-30T13:08:17Z
dc.date.issued2018-10-31
dc.date.submitted2018-01-04
dc.identifier.urihttps://www.repository.cam.ac.uk/handle/1810/276328
dc.description.abstractArabinogalactan proteins (AGPs) are proteoglycans heavily substituted by arabinogalactan polysaccharides. These are composed of arabinose and galactose, and minor sugars such as glucuronic acid (GlcA), fucose and xylose. The arabinogalactan polysaccharides do not decorate classical AGPs exclusively, but they can also be found decorating a wide range of proteins. Arabinogalactan proteins have been implicated in many processes of plant development. Recently, AGPs were proposed to bind and store calcium at the plasma membrane. They are extracellular, and are localised mainly at the plasma membrane via a GPI-anchor. They can also be soluble in the apoplast. Their low abundance, chemical similarity and high functional redundancy have hindered their study. My strategy to overcome these difficulties was to study knock-out Arabidopsis thaliana plants of glycosyltransferases that transfer sugars specifically onto AG-polysaccharides. Glucuronic acid makes up about 10% of the arabinogalactan polysaccharide structure in Arabidopsis thaliana cell culture AGPs. Previously, the glucuronic acid transferase A TGLCA T14A, a member of the CAZy Glycosyl Transferase 14 family, was shown to transfer GlcA specifically onto AGPs, and knock-out Arabidopsis plants showed a 30% reduction in [Me]GlcA substitution in AGP-enriched preparations. However, no clear growth phenotype was observed. The characterisation of knock-out plants of other GT14 family members and combinations thereof is described here. Based on previous studies (Lamport and Várnai, 2013), I assayed in vitro the calcium binding capacity of AGP extracts from WT and knock-out plants. The results showed that AGP extracts from knock-out plants can hold less calcium than WT plants in vitro. A wide range of plant growth phenotypes were identified. Growth phenotypes can be explained by changes in the cytoskeleton and deficiencies in calcium signaling. Our evidence suggests links between structural deficiencies of extracellular proteoglycans to extracellular calcium and cytoskeleton. This research has the potential to create a new model system for the study of molecular mechanisms dependent on calcium that drive cell expansion, division and differentiation in plants.
dc.description.sponsorshipConsejo Nacional de Ciencia y Tecnología (CONACYT) - México Cambridge Commonwealth, European & International Trust
dc.language.isoen
dc.rightsAttribution-NonCommercial-ShareAlike 4.0 International (CC BY-NC-SA 4.0)
dc.rights.urihttps://creativecommons.org/licenses/by-nc-sa/4.0/
dc.subjectarabinogalactan proteins
dc.subjectcell walls
dc.subjectcalcium
dc.subjectplasma membrane
dc.subjectCAZy
dc.subjectglucuronic acid
dc.subjectplant biology
dc.subjectplant biochemistry
dc.subjectGT14
dc.subjectglycosyltransferases
dc.subjectglucuronic acid transferases
dc.subjectO-glycans
dc.subjectglycosylation
dc.titleIDENTIFICATION OF THE ROLE OF [METHYL]GLUCURONIC ACID ON ARABINOGALACTAN POLYSACCHARIDES IN ARABIDOPSIS THALIANA
dc.typeThesis
dc.type.qualificationlevelDoctoral
dc.type.qualificationnameDoctor of Philosophy (PhD)
dc.publisher.institutionUniversity of Cambridge
dc.publisher.departmentDepartment of Biochemistry
dc.date.updated2018-05-30T09:58:00Z
dc.identifier.doi10.17863/CAM.23619
dc.contributor.orcidLópez Hernández, Federico [0000-0003-2916-3439]
dc.publisher.collegeMagdalene College
dc.type.qualificationtitlePhD in Biochemistry
cam.supervisorDupree, Paul
cam.supervisor.orcidDupree, Paul [0000-0001-9270-6286]
cam.thesis.fundingfalse
rioxxterms.freetoread.startdate2022-06-01


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Attribution-NonCommercial-ShareAlike 4.0 International (CC BY-NC-SA 4.0)
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