UCLA

Essential cellular processes involving the actin cytoskeleton are regulated by auxiliary proteins that can sense the nucleotide state of actin. Here we report cryo-EM structures for ADP-bound and ADP-beryllium fluoride (ADP-BeFx, an ADP-P i mimic)-bound actin filaments in complex with the β-propeller domain of yeast coronin 1 (crn1), at 8.6-Å resolution. Our structures reveal the main differences in the interaction of coronin with the two nucleotide states of F-actin. We derived pseudoatomic models by fitting the atomic structures of actin and coronin into the EM envelopes and confirmed the identified interfaces on actin by chemical cross-linking, fluorescence spectroscopy and actin mutagenesis. The models offer a structural explanation for the nucleotide-dependent effects of coronin on cofilin-assisted remodeling of F-actin.