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Figure 7
Vibrionaceae exo-acting GH9s versus the C. thermocellum cellobiohydrolase CbhA. (a) The exo-acting GH9s VC0615, PBPRA0520 and VP2484, alongside an CbhA E795Q mutant (PDB entry 1rq5; grey), in complex with an uncleaved cellotetraose substrate (grey sticks; white circles denote enzyme subsites). The loops in exo-acting GH9s from α-helices 1 to 2 (black; 112–162 in VC0615 numbering) and α-helices 9 to 10 (404–442) help to occlude the −2 subsite of exo-acting GH9s. The corresponding loops in CbhA (red; 117–183 and 454–471) do not occlude the −2 subsite. The α-helix 1–2 loop in exo-acting GH9s projects more `into' the enzyme binding site compared with the same loop in CbhA, creating more of a steric block against –2 subsite binding. (b) Clustal Omega (Sievers & Higgins, 2018BB25) alignment of the VC0615, PBPRA0520, VP2484 and CbhA sequences, with loops highlighted. Colours are as in (a).

ISSN: 2053-230X
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