Fig. 2: LONP1 employs two pore loop aromatic residues to facilitate substrate translocation.
From: Structures of the human LONP1 protease reveal regulatory steps involved in protease activation
a A twelve-residue polyalanine chain is modeled into the substrate density found in the substrate-bound human LONP1 structure, shown in a transparent orange surface representation. Y565 from pore-loop 1 (labeled P1) is shown using stick representations. Y565 residues from ATP1-4 and ADP1 subunits show intercalating, zipper-like interactions with substrate. Y599 from pore loop 2 (labeled P2) also shows intercalating interactions with substrate in the ATP1 (purple) and ATP2 (dark blue) subunits. b Sequence alignment between LONP1 homologs highlighting evolutionary conservation within pore loop 1 and Walker B motifs, as well as the evolutionary integration of a hydrophobic residue into pore loop 2 in metazoans. c Introducing pore loop mutations Y565A or Y599A shows a decrease in the degradation rate of a model substrate, FITC-casein. The hydrolysis-blocking Walker B mutation E591A is included as a control. Data are presented as bar graphs showing mean values with error bars showing standard deviation from three independent replicates. ****p < 0.0001 relative to wild type calculated by one-sided ANOVA. d Basal-level (filled bars) and casein-stimulated (hatched bar) ATPase rates are shown for the same mutations as in (c). Data are presented as bar graphs showing mean values with error bars showing standard deviation from three independent replicates. Error bars show standard deviation from three independent replicates.
