Expression pattern and subcellular localization of Arabidopsis purple acid phosphatase AtPAP9

• Analyzing T-DNA lines, the existence of two mRNA variants for AtPAP9 were shown.
• AtPAP9 was mainly expressed in stipule and vascular tissue in response to fungal infection.
• AtPAP9 could be involved in plasma membrane and cell wall adhesion, playing a signaling role.
• The variants differ for the N-terminal, producing both HMW and LMW phosphatases.
• A potential role in plasma membrane and cell wall adhesion for PAP9 protein is conceivable.

Purple acid phosphatase (PAP; EC 3.1.3.2) enzymes are metallophosphoesterases that hydrolysis phosphate ester bonds in a wide range of substrates. Twenty-nine PAP-encoding loci have been identified in the Arabidopsis genome, many of which have multiple transcript variants expressed in response to diverse environmental conditions. Having analyzed T-DNA insertion mutants, we have provided strong pieces of evidence that AtPAP9 locus encodes at least two types of transcripts, designated as AtPAP9-1 and AtPAP9-2. These transcript variants expressed distinctly during the course of growth in medium containing sufficient phosphate or none. Further histochemical analysis by the use of AtPAP9-1 promoter fused to β-glucuronidase reporter gene indicated the expression of this gene is regulated in a tissue-specific manner. AtPAP9-1 was highly expressed in stipule and vascular tissue, particularly in response to fungal infection. Subcellular localization of AtPAP9-1:green fluorescent fusion protein showed that it must be involved in plasma membrane and cell wall adhesion.

AtPAP9 locus encodes at least two types of transcripts, designated as AtPAP9-1 and AtPAP9-2. These transcript variants expressed distinctly during the course of growth in medium containing sufficient or no phosphate.Figure optionsDownload high-quality image (66 K)Download as PowerPoint slide