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Copper transport into the chloroplast and its implications for copper homeostasis in Arabidopsis thaliana

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dc.contributor.authorTapken, Wiebke, author
dc.contributor.authorPilon, Marinus, advisor
dc.contributor.authorChisholm, Stephen, committee member
dc.contributor.authorPilon-Smits, Elizabeth, committee member
dc.contributor.authorReddy, Anireddy S. N., committee member
dc.date.accessioned2007-01-03T08:26:52Z
dc.date.available2007-01-03T08:26:52Z
dc.date.issued2012
dc.description.abstractCopper (Cu) is an essential micronutrient for most aerobic organisms including plants. It is present as Cu+ or Cu2+, which makes it an ideal cofactor for enzymes involved in processes such as photosynthesis and respiration. Plant cuproproteins are almost ubiquitously found in every cell compartment. The blue Cu protein plastocyanin (PC) is believed to bind the majority of Cu ions in green tissues and is essential for higher plants. Cu reaches the thylakoid lumen through the activity of two P1B-type ATPases called PAA1/HMA6 and PAA2/HMA8 (P-type ATPase of Arabidopsis/Heavy-metal ATPase), which are located in the inner chloroplast envelope and the thylakoid lumen respectively. Under Cu limiting conditions, plants have been suggested to prioritize cellular Cu to PC to ensure adequate photosynthesis. This process involves the post-transcriptional down-regulation of seemingly less essential cuproproteins through the activity of a single transcription factor called SPL7 (SQUAMOSA promoter binding protein-like7). The first chapter reviews Cu homeostasis in plants. The research presented in the three experimental chapters of this dissertation is aimed to determine the role of the chloroplast in Cu homeostasis of Arabidopsis thaliana. I report a novel SPL7-independent and chloroplast-specific regulation of the thylakoid-localized Cu transporter PAA2/HMA8. The transporter is most abundant in the absence of Cu and is turned over at higher chloroplastic Cu concentrations. PAA2/HMA8 abundance in Cu deficiency is furthermore controlled by the presence of PC, because in a pc mutant PAA2/HMA8 abundance is always low. The regulation of the transporter likely serves as a checkpoint for the Cu requirements of the thylakoid lumen. I identified two components of the stroma-localized Clp protease (Caseinolytic peptidase) which are involved in PAA2/HMA8 turnover. The Cu status of these mutants is not affected, decreasing the likelihood of a secondary affect of Cu on PAA2/HMA8 in these plants. In the last experimental chapter I summarize relevant results that further describe and characterize PAA1 and PAA2. Most notably, Arabidopsis encodes for a splice-form of PAA1. This much smaller fragment is expressed with a chloroplast targeting sequence and could potentially function as a stromal Cu chaperone.
dc.format.mediumborn digital
dc.format.mediumdoctoral dissertations
dc.identifierTapken_colostate_0053A_11449.pdf
dc.identifierETDF2012500355BIOL
dc.identifier.urihttp://hdl.handle.net/10217/71670
dc.languageEnglish
dc.language.isoeng
dc.publisherColorado State University. Libraries
dc.relation.ispartof2000-2019
dc.rightsCopyright and other restrictions may apply. User is responsible for compliance with all applicable laws. For information about copyright law, please see https://libguides.colostate.edu/copyright.
dc.subjecthomeostasis
dc.subjectcopper
dc.subjectP type ATPase
dc.subjectchloroplast
dc.subject.lcshArabidopsis
dc.titleCopper transport into the chloroplast and its implications for copper homeostasis in Arabidopsis thaliana
dc.typeText
dcterms.rights.dplaThis Item is protected by copyright and/or related rights (https://rightsstatements.org/vocab/InC/1.0/). You are free to use this Item in any way that is permitted by the copyright and related rights legislation that applies to your use. For other uses you need to obtain permission from the rights-holder(s).
thesis.degree.disciplineBiology
thesis.degree.grantorColorado State University
thesis.degree.levelDoctoral
thesis.degree.nameDoctor of Philosophy (Ph.D.)

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