Adenosine 3´,5´-bisphosphate (PAP)-mediated inter-compartmental metabolite signalling and intracellular transport of 3´-phosphoadenosine 5´-phosphosulfate (PAPS) and PAP in Arabidopsis thaliana
Final Report Abstract
Plant cells are highly compartmentalized, thus requiring a complex set of subcellular messages, including multiple retrograde signals from chloroplasts and mitochondria to the nucleus to regulate gene expression. 3´- phosphoadenosine 5´-phosphate (PAP) has been proposed as a mobile signal molecule in retrograde signalling. FIERY1 (FRY1) is a 3'(2') 5'-bisphosphate nucleotidase, which dephosphorylates PAP to AMP both in plastids and mitochondria and was suggested to be involved in intercompartmental signalling. To dissect the role of FRY1 protein in chloroplasts, mitochondria, nuclei and the cytosol, we have complemented the fry1 mutant with FRY1 specifically directed to these cell compartments. Using this approach we could demonstrate that chloroplasts and especially mitochondria are central compartments to sense and detoxify PAP. In addition to FRY1, the levels of cellular PAP seems to be regulated by the 3’-phosphoadenosine-5’- phosphosulphate (PAPS) - PAP antiporter 1 (PAPST1) and -2 (PAPST2) as well as affected by adenosine 5'-phosphosulphate kinase (APK) enzymes 1-4 synthesising PAPS. To address the role of APKs and PAPSTs in PAP metabolism, we generated multiple fry1apk1/2/3, fry1apk1/2/4 as well as fry1papst1 and fry1papst2 mutants and addressed the complementation along with the determination of PAP levels. Finally, we analysed the compartment-specific distribution of PAP in fry1, fry1papst1 and fyr1papst2 mutants using a non-aqueous fractionation. Using these approaches we could demonstrate the importance of the cytosol in sensing high PAP levels, of the vacuole in storage of PAP and specifically of mitochondria in effective detoxification of PAP. The severe growth phenotype of the fry1papst2 mutant could be attributed to high PAP levels accumulating in the cytosol and substantiated the unforseen role of mitochondria-localised PAPST2 in PAP signalling and detoxification.
Publications
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(2012) The Arabidopsis thylakoid ADP/ATP carrier TAAC has a primary role in supplying plastidic phosphoadenosine 5´-phosphosulfate (PAPS) to the cytosol. Plant Cell 24: 4187-4204
Gigolashvili T, Geier M, Ashykhmina N, Frerigmann F, Wulfert S, Krueger S, Mugford SG, Kopriva S, Haferkamp I, Flügge UI
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(2014) bHLH05 is an interaction partner of MYB51 and a novel regulator of glucosinolate biosynthesis in Arabidopsis thaliana. Plant Physiology. 166: 349-369
Frerigmann H, Berger B and Gigolashvili T
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(2014) The three MYB transcription factors MYB34, MYB51 and MYB122 exert distinct regulation on indolic glucosinolate biosynthesis in Arabidopsis thaliana. Mol. Plant 7 (5): 814-828
Frerigmann H and Gigolashvili T
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(2015) The role of MYB34, MYB51 and MYB122 in the regulation of camalexin biosynthesis in Arabidopsis thaliana. Front. Plant Sci. 08/2015; 6
Frerigmann H, Glawischnig E, Gigolashvili T
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(2016) Sensing and signaling of oxidative stress in chloroplasts by inactivation of the SAL1 phosphoadenosine phosphatase Proc. Natl. Acad. Sci. USA 113(31): 4567-4576
Chan KX, Mabbitt PD, Phua SY, Mueller JW, Nisar N, Gigolashvili T, Stroeher E, Grassl J, Arlt W, Estavillo GM, Jackson CJ, Pogson BJ
