Abstract

Purine nucleoside phosphorylases (PNP) are enzymes thought to be involved in purine metabolism and may have important roles in development. PNPs are rarely reported in plants. A group of poplar proteins: bark storage protein (BSP) and wound inducible (Win4) are the homologues of PNP in plants. Dr Hanke’s lab has identified a protein, cytokinin riboside phosphorylase, which is encoded by the gene locus At4g28940. In Arabidopsis thaliana At4g24340 and At4g24350 are the only other genes encoding proteins predicted to have purine riboside phosphorylase activity. They closely resemble the BSP /Win4 homologues in poplar. In this study the full length sequences of the two versions of At4g24340 and one of At4g24350 have been cloned in the pMal system and protein expressed for enzyme studies. The system yielded a MBP ::protein-of-interest fusion product which has been purified by affinity chromatography. The present aim is to characterise the two predicted PNPs, At4g24340 and At4g24350, determining their enzyme activity, accumulation and the localisation of transcripts and proteins in plant tissues and cell.