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Research article - Peer-reviewed, 2007

On the phylogeny, expression and targeting of plant nucleoside diphosphate kinases

Hammargren J, Sundstrom J, Johansson M, Bergman P, Knorpp C


The plant nucleoside diphosphate kinase (NDPK, EC gene family consists of three groups whose gene products are found in different subcellular locations. In this study we discuss the evolutionary history, localization and expression of the NDPK genes, addressing the question of functional specialization of the different NDPKs. A phylogenetic analysis revealed that the three NDPK isoforms were present already in the last common ancestor of vascular plants and mosses. Our data also imply that the NDPK3 genes possess a higher degree of conservation than the NDPK1 and NDPK2 genes. The expression levels of the different NDPKs in Arabidopsis thaliana inflorescences, leaves and roots were evaluated using quantitative PCR as well as in silico methods. This analysis showed that NDPK1 is the most highly expressed NDPK gene in all the studied tissues. NDPK3a has the second highest NDPK expression, while NDPK3b is expressed to a very low extent. However, expression of NDPK3b is elevated in inflorescence tissue. In situ hybridization experiments performed on inflorescences showed NDPK3a expression in actively dividing cells. NDPK3b expression was observed during later stages of flower development, specifically in the tapetum, ovules and petals. Additionally, we show that an NDPK3 protein is able to direct the green fluorescent protein to both mitochondria and chloroplasts using transient expression in leaf protoplasts. The dual localisation of NDPK3 was confirmed by Western blot, which also demonstrated that the majority of the NDPK3 protein is found in the mitochondria

Published in

Physiologia Plantarum
2007, Volume: 129, number: 1, pages: 79-89