Fig. 5
Phylogeny, biochemical characterization and tissue localization of insect AA15 LPMOs. a Maximum likelihood phylogenetic tree showing the AA15 coding sequences identified in the genome of three model insect species (D. melanogaster, T. castaneum, and A. gambiae), one model crustacean (Hyalella azteca), and in the transcriptome of T. domestica (Supplementary Notes 2, 4–7). Each tree branch is colored according to the species. The axial residue of each protein is indicated with a letter (Y = tyrosine, F = phenylalanine, T = threonine). Blue asterisks mark TdAA15A and the TdAA15B. Magenta asterisks mark DmAA15A and DmAA15B. MALDI-TOF MS spectra of products obtained after incubation of 4 mg mL−1 α-chitin (b) and β-chitin (c) with 2 µM TdAA15B and 4 mM gallic acid for 24 h, showing native and oxidized oligosaccharides. The main peaks correspond to mono- or di-sodiated adducts of C1-aldonic acids, imparting +16 or +38 m/z respectively, relative to the mono-sodiated unoxidized form. Smaller peaks for the mono-sodiated lactone (−2) were also identified. In b and c, 100% relative intensity represents 2.9 × 104 and 1.3 × 104 arbitrary units (a.u.), respectively. Insets are expanded mass spectra for DP5 (b) and DP7 (c) products. Spectra of the negative control reactions are included in Supplementary Fig. 12c–f and do not show any native or oxidized species. d CAZymes identified in the proteome of the midgut from D. melanogaster larvae (whole tissue). The only LPMO identified in this sample is DmAA15B. e CAZymes identified in the proteome of the tracheal system from D. melanogaster larvae (whole tissue). Only one LPMO (DmAA15A) was detected and represents about 8% of the total CAZymes in the trachea. The most abundant GH family (GH18) includes several chitinases (accessions: X2JEB6, M9PGH3, Q9VFR3, A0A0B4LFJ1, D4G7B1, X2JA18, Q8MM24, M9NDS9), compatible with roles in chitin remodeling
