Comparative genomics of pectinacetylesterases: Insight on function and biology

Abstract

Pectin acetylation influences the gelling ability of this important plant polysaccharide for the food industry. Plant apoplastic pectinacetylesterases (PAEs) play a key role in regulating the degree of pectin acetylation and modifying their expression thus represents one way to engineer plant polysaccharides for food applications. Identifying the major active enzymes within the PAE gene family will aid in our understanding of this biological phenomena as well as provide the tools for direct trait manipulation. Using comparative genomics we propose that there is a minimal set of 4 distinct PAEs in plants. Possible functional diversification of the PAE family in the grasses is also explored with the identification of 3 groups of PAE genes specific to grasses.

Keywords: acetylation; cell walls; comparative genomics; pectin; pectinacetylesterases; phylogeny.

Figure 1.

Phylogenetic tree of Arabidopsis thaliana and species containing reduced numbers of PAE genes in their genomes. Arabidopsis PAEs numbers are indicated to the right. Red brackets indicate paralogous genes. Protein sequence alignments were performed using MUSCLE and Tree calculated by neighborjoining using BLOSUM62 by the Jalview 2.8.2 software package.

Figure 2.

Acetate content of PAE2 overexpression lines cell walls (A) and pectin extracts (B). Measurements made on 35 day old rosette leaf material (for method detail see ref. ⁴). Asterisk indicates significant differences based on t test (P < 0.05; n ≥ 2).

Figure 3.

Phylogenetic tree of Grass PAEs along with other reference species. Arabidopsis PAEs numbers are indicated to the right. Black brackets indicates clades exclusive to grasses. Protein sequence alignments were performed using MUSCLE and Tree calculated by neighborjoining using BLOSUM62 by the Jalview 2.8.2 software package.