Trehalases: a neglected carbon metabolism regulator?

Abstract

Trehalases are enzymes that carry out the degradation of the non-reducing disaccharide trehalose. Trehalase phylogeny unveiled three major branches comprising those from bacteria; plant and animals; and those from fungal origin. Comparative analysis between several deduced trehalase structures and the crystallographic structure of bacterial trehalase indicated that these enzyme's structures are highly conserved in spite of the marked differences found at the sequence level. These results suggest a bacterial origin for the trehalases in contrast to an eukaryotic origin, as previously proposed. Trehalases structural analysis showed that they contain six discrete motifs which are characteristic of each phylogenetic group, suggesting a positive evolutionary selection pressure for the structural conservation. Interestingly, trehalases are involved in multiple regulatory functions: In the response against pathogens (plant-pathogen interactions); the regulation of bacterial viability in symbiotic interactions (legume-Rhizobium); carbon partitioning in plants; regulating chitin biosynthesis, as well as energy supply in the hemolymph for flight, in insects. In summary, trehalases seem to have a prokaryotic origin and play an active role in carbon metabolism and other diverse regulatory effects on cell physiology.

Keywords: Trehalases; carbon-metabolism; structural conservation and distribution.

Figure 1. Trehalases: phylogenetic analysis, motifs and catalytic residues distribution are shown. The scale represents the estimated branch lengths (neighbor-joining method, 1,000 bootstrap replicates). Three phylogenetic groups are highlighted and the corresponding motifs in each group are described in the text.

Figure 2. Homology model comparison with the EcTRE template structure (PDB code: 2WYN) and the trehalase deduced structures from diverse origins. (A) RMSD average values obtained from the comparison between the crystallographic structure (bacteria) and the deduced structures of trehalases from different origins. (B) Superimposition of all the trehalases (crystallographic and deduced structures). (C) Motifs and residues with a strong trend for synonymous mutations are depicted.