Extended Data Fig. 9: Comparison of PsChs1 and Rhodobacter sphaeroides bacterial cellulose synthase A (RsBcsA) and molecular dynamics simulation.
a, The structures of PsChs1 and RsBcsA are superimposed by ChimeraX and depicted in two perspectives. The catalytic domains are magnified (right). Functionally important residues are labeled and shown as sticks. b, Dimensions of (GlcNAc)4 and (Glc)4. The structures of the (GlcNAc)4 and (Glc)4 oligosaccharides were downloaded from the PDB database (5Y2C and 4HG6). c, Length and diameter of the presumed chitin (left, green mesh) and cellulose (right, orange mesh) channels of PsChs1 and RsBcsA, calculated by PyMOL Caver plugin. The calculated channel of RsBcsA fits perfectly with the dimension of the cellulose chain included in the RsBcsA crystal structure. d, Structural comparison of the VLPGA loop with BcsA’s FFCGSA loop. e, Structure-weighted sequence alignment of the catalytic domains of RsBcsA and PsChs1. Conserved motifs are labeled and indicated by black boxes. f, Backbone RMSD of apo PsChs1 (closed conformation) and product-bound PsChs1 (open conformation) during the MD simulation of 50 ns. g, From a snapshot of 50 ns, apo PsChs1 shows little permeability for water (red ball), while product-bound PsChs1 (with the removal of UDP/(GlcNAc)3 in the simulations) shows water flow through the channel. h, The chitin sheets are self-assembled in an anti-parallel manner along the b-axis to finally form α-chitin.
