Fig. 6
Structural homology of F. oxysporum Xyl2 with fungal GH11 xylanases. a Superposition of F. oxysporum Xyl2 with structural homologous GH11 xylanases of fungal origin, including Trichoderma reesei Xyl2 (TrXyl2, yellow), T. longibrachiatum Xyl2 (TlXyl2, violet), T. harzianum Xyl2 (ThXyl2, gray) and Chaetomium thermophilum Xyl11A (CtXyl11A, green). b Multiple sequence alignment with secondary structural elements overlaid in pink (β-strands) or cyan (helix α1), and the 310A helix motif (Pro22-Asn23-Ser24) is boxed with a blue outline. An orange background represents active site residues. An asterisk is shown on top of Pro5 to indicate that it participates in the substrate binding thanks to the unusual conformation of the N-terminal end of Xyl2. c Comparison of the atypical conformation adopted by the N-terminal extreme of Xyl2 (in cyan) in comparison with all other GH11 xylanases (in yellow), with the electron density map (contoured at 1σ) overlaid to support the observed configuration. d Close-up onto the 310A helix motif showing the electron density map (contoured at 1σ), connecting β-strands β2 and β3 by a tight turn