Diversity of the manganese lipoxygenase gene family - A mini-review

Analyses of fungal genomes of escalate from biological and evolutionary investigations. The biochemical analyses of putative enzymes will inevitably lag behind and only a selection will be characterized. Plant-pathogenic fungi secrete manganese-lipoxygenases (MnLOX), which oxidize unsaturated fatty acids to hydroperoxides to support infection. Six MnLOX have been characterized so far including the 3D structures of these enzymes of the Rice blast and the Take-all fungi. The goal was to use this information to evaluate MnLOX-related gene transcripts to find informative specimens for further studies. Phylogenetic analysis, determinants of catalytic activities, and the C-terminal amino acid sequences divided 54 transcripts into three major subfamilies. The six MnLOX belonged to the same "prototype" subfamily with conserved residues in catalytic determinants and C-terminal sequences. The second subfamily retained the secretion mechanism, presumably necessary for uptake of Mn²⁺, but differed in catalytic determinants and by cysteine replacement of an invariant Leu residue for positioning ("clamping") of fatty acids. The third subfamily contrasted with alanine in the Gly/Ala switch for regiospecific oxidation and a minority contained unprecedented C-terminal sequences or lacked secretion signals. With these exceptions, biochemical analyses of transcripts of the three subfamilies appear to have reasonable prospects to find active enzymes.