Molecular and functional characterization of a PEX14 cDNA from rice

In contrast to the translocation mechanisms determined in yeasts and mammalian cells, there is little information on the functions of plant peroxisomal proteins or their genomic structures. To understand the role that PEX14 plays in diverse plant peroxisomal functions and how peroxisomal translocation is mediated in plant cells, we cloned a 1827 bp cDNA encoding the peroxisomal membrane protein OsPex14p from a rice leaf cDNA library. The 54 kDa OsPex14p, which has a theoretical p I value of 6.06, contains a highly conserved N-terminal domain and a short putative transmembrane domain. The OsPEX14 gene in the rice genome exists as a single-copy gene, consists of eleven exons interrupted by ten introns, and spans about 5 kb of chromosome 5. The 5′-flanking region contains putative cis-acting light-responsive elements, and the transcription initiation site maps 114 bp upstream of the translation start codon. OsPEX14 mRNA is highly expressed in leaf tissues and is induced by exposure to several stresses. Heterologous expression of OsPex14p suppresses the defect in targeting of peroxisomal matrix proteins in a pex14 null mutant of Saccharomyces cerevisiae.