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Figure 6
Vibrionaceae exo-acting GH9s versus an endo-acting GH9 enzyme. (a) (α/α)6-domain alignment of the exo-acting GH9s VC0615 (colours as in Fig. 5[link]), PBPRA0520 (PDB entry 5drq; green) and VP2484 (PDB entry 3h7l; purple), alongside the endo-acting GH9 Tf-Cel9a from T. fusca (PDB entry 4tf4; teal), in complex with a cleaved cellohexaose substrate (teal sticks; white circles denote enzyme subsites). Extended loops in exo-acting GH9s from α-­helices 1 to 2 (black; 112–162 in VC0615 numbering) and α-helices 9 to 10 (black; 404–442) form steric blocks which close off the binding pockets of these enzymes. The corresponding loops in Tf-Cel9a (red; 20–63 and 292–315) are smaller and do not obstruct the substrate-binding cleft. (b) Clustal Omega (Sievers & Higgins, 2018BB25) alignment of the VC0615, PBPRA0520, VP2484 and Tf-Cel9a sequences, with loop sequences highlighted. The large disparity in loop sizes causes suboptimal alignment by Clustal Omega in the α-helix 9–10 region. Colours are as in (a).

ISSN: 2053-230X
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