The Arabidopsis apyrase AtAPY1 is localized in the Golgi instead of the extracellular space

BMC Plant Biology

Research Article

Thomas Kurth¹  Carolin Massalski²  Madlen Schiller²  Iris Steinebrunner² 

[1] DFG-Center for Regenerative Therapies Dresden (CRTD), Technische Universität Dresden, Fetscherstraße 105, 01307, Dresden, Germany;Department of Biology, Section of Molecular Biotechnology, Technische Universität Dresden, Helmholtzstraße 10, 01069, Dresden, Germany;

关键词: Apyrase;    Regulation of growth;    Golgi;    Extracellular ATP;    Transmembrane protein;    SNAP-tag;    GFP-tag;    Co-localization;    Substrate specificity;   

DOI  :  10.1186/1471-2229-12-123

 received in 2012-01-30, accepted in 2012-07-09,  发布年份 2012

来源: Springer

【 摘 要 】

BackgroundThe two highly similar Arabidopsis apyrases AtAPY1 and AtAPY2 were previously shown to be involved in plant growth and development, evidently by regulating extracellular ATP signals. The subcellular localization of AtAPY1 was investigated to corroborate an extracellular function.ResultsTransgenic Arabidopsis lines expressing AtAPY1 fused to the SNAP-(O6-alkylguanine-DNA alkyltransferase)-tag were used for indirect immunofluorescence and AtAPY1 was detected in punctate structures within the cell. The same signal pattern was found in seedlings stably overexpressing AtAPY1-GFP by indirect immunofluorescence and live imaging. In order to identify the nature of the AtAPY1-positive structures, AtAPY1-GFP expressing seedlings were treated with the endocytic marker stain FM4-64 (N-(3-triethylammoniumpropyl)-4-(p-diethylaminophenyl-hexatrienyl)-pyridinium dibromide) and crossed with a transgenic line expressing the trans-Golgi marker Rab E1d. Neither FM4-64 nor Rab E1d co-localized with AtAPY1. However, live imaging of transgenic Arabidopsis lines expressing AtAPY1-GFP and either the fluorescent protein-tagged Golgi marker Membrin 12, Syntaxin of plants 32 or Golgi transport 1 protein homolog showed co-localization. The Golgi localization was confirmed by immunogold labeling of AtAPY1-GFP. There was no indication of extracellular AtAPY1 by indirect immunofluorescence using antibodies against SNAP and GFP, live imaging of AtAPY1-GFP and immunogold labeling of AtAPY1-GFP. Activity assays with AtAPY1-GFP revealed GDP, UDP and IDP as substrates, but neither ATP nor ADP. To determine if AtAPY1 is a soluble or membrane protein, microsomal membranes were isolated and treated with various solubilizing agents. Only SDS and urea (not alkaline or high salt conditions) were able to release the AtAPY1 protein from microsomal membranes.ConclusionsAtAPY1 is an integral Golgi protein with the substrate specificity typical for Golgi apyrases. It is therefore not likely to regulate extracellular nucleotide signals as previously thought. We propose instead that AtAPY1 exerts its growth and developmental effects by possibly regulating glycosylation reactions in the Golgi.

【 授权许可】

Unknown   
© Schiller et al.; licensee BioMed Central Ltd. 2012. This article is published under license to BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.