Clustered genes within the genome of Arabidopsis thaliana encoding pectin methylesterase-like enzymes.

We focused our attention on the isolation and regulation of genes encoding for pectin methylesterase (PME) isoenzymes in Arabidopsis thaliana (At). The present data reports the identification of two PME-like genes, named AtPME1 and AtPME2, that are closely linked in the At genome. These genes possess different structural organisations. While all higher plant PME characterised so far possess an intron at a similar location relative to their coding sequence, AtPME2 shows an additional intron whose presence within other higher plant PME-like genes has not been previously reported. Sequence comparison of the N-terminal region suggests that the secretory pathways of the putative AtPME1 and AtPME2 isoforms are different, and that this region may contribute to specify a biological function to each isoform. Moreover, phylogenetic analysis reflects the possible existence of functional groups of PME isoforms in higher plant species that seem to have been conserved during evolution.