Fig. 3: Cryo-EM 3D structure of the substrate-free G. haemolysans IgA1P with comparisons to of the substrate-free S. pneumoniae IgA1P.
From: A substrate-induced gating mechanism is conserved among Gram-positive IgA1 metalloproteases
a 3D single particle reconstruction of G. haemolysans IgA1P residues 907-2201 colored according to local resolution estimates (units in Å). b Density is shown from the single particle reconstruction along with the ribbon model of G. haemolysans IgA1P. Each domain is colored as described in Fig. 1b. c Structural superposition of G. haemolysans IgA1P residues 907-2201 (colored by domain) with S. pneumoniae IgA1P residues 665-1963 previously solved (white)9. d Blow-up of the active site of the conserved metalloprotease motif. The Zn-coordinating G. haemolysans IgA1P glutamic acid residues (red) and histidine residues (blue) are shown along with the same residues within the S. pneumoniae IgA1P (white). Residue numbers for the S. pneumoniae IgA1P are in brackets. e Structural comparison of the NTD2 domains and loops that occlude the active site. The explicit 6 Å conformational repositioning of this domain between the two substrate-free metallo-IgA1Ps is highlighted. Structural alignments were conducted in Chimera using all domains of the metallo-IgA1P for a least-squares RMSD superposition.
