Characterization of a putative human 5-lipoxygenase activating protein sequence encoded in Arabidopsis thaliana
Patwardhan, Vandana A.
MetadataShow full item record
Lipoxygenase is a ubiquitous enzyme that can oxidize free fatty acids containing a cis, cis -1, 4- pentadiene structure. This action forms fatty acid hydroperoxides which are precursors to compounds of medicinal importance. Plant tissues contain high levels of lipoxygenase activity which has been implicated in the production of many volatile compounds. These compounds can be involved with plant-insect interaction as well as production of off-flavors by plants. Since the 18kDa 5-lipoxygenase activating protein (FLAP) of mammals has been shown to be a key step in controlling lipoxygenase activity, our aim was to establish whether plants had a similar control mechanism. We have employed a human FLAP gene as a heterologous probe to screen a Arabidopsis thaliana genomic DNA library. Three independent cross hybridizing phage plaques were isolated. All three clones shared similar restriction fragments suggesting that they were either overlapping clones or that these sequences are part of a small gene family. We have subcloned one of these genomic clones. Partial sequencing of this putative fragment reveals very little homology to human FLAP. However, high homology domains have been identified between the Arabidopsis thaliana putative genomic DNA and guinea pig lipoprotein lipase DNA. Northern analysis using the total RNA from the entire plant and the putative genomic fragment shows hybridization with a 2.4 kb RNA transcript. These results suggest that although an exact analog plant analog of the human FLAP may not exist in Arabidopsis thaliana, a protein with domains performing related functions to human FLAP may be present.