Differential phylogenetic expansions in BAHD acyltransferases across five angiosperm taxa and evidence of divergent expression among Populus paralogues

Abstract

BackgroundBAHD acyltransferases are involved in the synthesis and elaboration of a wide variety of secondary metabolites. Previous research has shown that characterized proteins from this family fall broadly into five major clades and contain two conserved protein motifs. Here, we aimed to expand the understanding of BAHD acyltransferase diversity in plants through genome-wide analysis across five angiosperm taxa. We focus particularly on Populus, a woody perennial known to produce an abundance of secondary metabolites.ResultsPhylogenetic analysis of putative BAHD acyltransferase sequences from Arabidopsis, Medicago, Oryza, Populus, and Vitis, along with previously characterized proteins, supported a refined grouping of eight major clades for this family. Taxon-specific clustering of many BAHD family members appears pervasive in angiosperms. We identified two new multi-clade motifs and numerous clade-specific motifs, several of which have been implicated in BAHD function by previous structural and mutagenesis research. Gene duplication and expression data for Populus-dominated subclades revealed that several paralogous BAHD members in this genus might have already undergone functional divergence.ConclusionsDifferential, taxon-specific BAHD family expansion via gene duplication could be an evolutionary process contributing to metabolic diversity across plant taxa. Gene expression divergence among some Populus paralogues highlights possible distinctions between their biochemical and physiological functions. The newly discovered motifs, especially the clade-specific motifs, should facilitate future functional study of substrate and donor specificity among BAHD enzymes.

Evolutionarily Distinct BAHD N-acyltransferases are Responsible for Natural Variation of Aromatic Amine Conjugates in Rice

“…The resulting phylogenetic tree is consistent with that of Tuominen et al (2011), an updated version of that from D'Auria, who sorted biochemically characterized BAHD acyltransferases into eight major clades (A) An unrooted phylogenetic tree was constructed as described in Methods. Twenty-seven biochemically characterized BAHD proteins and five GNAT proteins were collected.…”

“…The functional assignment of eight N-acyltransferases in clade IV presented us with an opportunity to examine the characteristics of this barely characterized subgroup of BAHD acyltransferases (D 'Auria, 2006;Yu et al, 2009;Tuominen et al, 2011). When protein sequences of this clade were subjected to motif analysis using MEME (Bailey et al, 2015), we found the two BAHD family-conserved functional domains, HXXXD and DFGWG (Ma et al, 2005;D'Auria, 2006), and two clade IV-specific motifs (Supplemental Figures 7A and 7B).…”

“…Clade IV, which had only five members in the tree of Tuominen et al (2011), was further expanded into IVa and IVb in following analysis ( Figure 4A). Candidates for four out of the five loci identified grouped in clade IV, which is enriched in monocot genes, while candidates for the remaining locus were grouped into clade Vb, which is mainly made up of enzymes closely related to hydroxycinnamoyl transferases responsible for the biosynthesis of chlorogenic acid and monolignols (D'Auria, 2006).…”

“…The BAHD acyltransferase family was named according to the first letter of each of the first four biochemically characterized enzymes of this family BEAT (benzoyl alcohol O-acetyltransferase), AHCT (anthocyanin O-hydroxycinnamoyl transferase), HCBT (anthranilate N-hydroxycinnamoyl/benzoyl transferase), and DAT (deacetyl vindoline 4-O-acetyltransferase) (St-Pierre and De Luca, 2000). So far, enzymes involved in the biosynthesis of PAs have been identified from three (I, IV, and V) of the five clades of BAHD acyltransferases (D'Auria, 2006;Yu et al, 2009;Tuominen et al, 2011). ACTs (agmatine coumaroyl transferases) were characterized in barley and in Arabidopsis thaliana (Burhenne et al, 2003;Muroi et al, 2009).…”

The Last Step in Cocaine Biosynthesis Is Catalyzed by a BAHD Acyltransferase

“…The activities of the remaining five BAHD-like enzymes remain to be determined. It is expected that the E. coca genome should contain more members of the BAHD acyltransferase family since Arabidopsis (Arabidopsis thaliana) and Populus trichocarpa contain approximately 60 and 150 unique members, respectively (D 'Auria, 2006;Tuominen et al, 2011).…”