Extended Data Fig. 4: Flexibility, substrate binding and surface electrostatic potential of CphA1.
From: Structures and function of the amino acid polymerase cyanophycin synthetase
a, Local resolution estimates of the cryo-EM maps of tetrameric SuCphA1 (left) and dimeric AbCphA1 (right). b, Overlay of the two chains in the crystal structure of TmCphA1 (light blue) on the cryo-EM structure of SuCphA1 (colored), showing the different conformation adopted by Mlid of the crystal structure chain A and Glid in chain B. Mlid is not visible in chain B. c, Overlay of the unsharpened maps of SuCphA1 without cyanophycin substrate analogs (gray), and with (Asp-Arg)8-NH2 (red, right) and (Asp-Arg)8-Asn (blue, left). Clear extra density is visible in the maps calculated in the presence of substrate analogs, mostly near the active sites and the N domain. (Asp-Arg)8-Asn is also seen as product in the G domain active site, but no density is visible for the terminal Asn residue. d, Surface electrostatic potential maps of SuCphA1 and TmCphA1 dimers showing how the side that faces the active sites is lined with negatively and positively charged patched. The side facing the inner cavity, which is opposite the active sites, is mostly neutral. Active sites are marked with *, αa and αb are marked with rectangles.
