Cytochromes P450

Abstract

There are 244 cytochrome P450 genes (and 28 pseudogenes) in the Arabidopsis genome. P450s thus form one of the largest gene families in plants. Contrary to what was initially thought, this family diversification results in very limited functional redundancy and seems to mirror the complexity of plant metabolism. P450s sometimes share less than 20% identity and catalyze extremely diverse reactions leading to the precursors of structural macromolecules such as lignin, cutin, suberin and sporopollenin, or are involved in biosynthesis or catabolism of all hormone and signaling molecules, of pigments, odorants, flavors, antioxidants, allelochemicals and defense compounds, and in the metabolism of xenobiotics. The mechanisms of gene duplication and diversification are getting better understood and together with co-expression data provide leads to functional characterization.

Regioselective Biocatalytic Hydroxylation of Fatty Acids by Cytochrome P450s

“…The eukaryotic classes CYP1 and CYP2 demonstrate in-chain hydroxylation with sometimes outstanding selectivity, such as the strict ω-6 hydroxylation of C12:0 by Cyp2M1 from Oncorhynchus mykiss (Rainbow trout; Table 5, entry 24) [83]. CYP classes from plants, that perform in-chain hydroxylation of fatty acids include CYP77, CYP81, CYP96, CYP703, and CYP709 [32,33]. Two selective orthologues that were heterologously expressed in yeast are CYP703 from Arabidopsis thaliana (mainly active on carbon number 7 of C10:0, C12:0, and C14:0) [98] and CYP81B1 from Helianthus tuberosus (carbon number 7 and 8 in C10:0, C12:0, and C14:0) [99].…”

“…Substrate concentrations, stereo-, and the regio-selectivity achieved by wildtype enzymes and variants are summarized and only variants with described sequences and reasonable overexpression level are considered. Other systems were described elsewhere [19,20,[31][32][33][34][35]. Active site geometries and the amino acids that are responsible for the enzymes regio-selectivity are discussed in the individual chapters.…”

A Role for TIC55 as a Hydroxylase of Phyllobilins, the Products of Chlorophyll Breakdown during Plant Senescence

“…Thus, seemingly these are nonessential reactions in chlorophyll degradation. Nevertheless, the fact that all three, i.e., TIC55, CYP89A9, and MES16, are members of protein subfamilies with three, seven, and three members, respectively, in Arabidopsis (Gray et al, 2004;Bak et al, 2011;Christ et al, 2012), suggests that they have been specifically recruited during evolution to function in chlorophyll breakdown. This implies that phyllobilins could possibly play a role beyond being merely degradation products.…”

Plant P450s as versatile drivers for evolution of species-specific chemical diversity

“…Based on the available sequences, land plant P450s can be grouped in 11 phylogenetically distinct clans [4,5]. However, it is to be expected that new clans will emerge as older plant lineages are sequenced, as seen when the genome of the green algae Chlamydomonas was released.…”