Figure 3 - full size



	Figure 3 - full size

Figure 3.
Figure 3: Structural basis for proteasome inhibition by syrbactins. a, Chemical structure of SylA and GlbA. Red, , -unsaturated carbonyl group reacting with Thr1O^ ; green, dipeptide bond stabilizing the inhibitor upon proteasome binding; blue, molecule part determining active site specificity; yellow, aliphatic tail of GlbA. b, Mechanism of binding of SylA/GlbA to the active site Thr1. c, d, Stereo representation of the chymotryptic-like active site (rose, subunit 5; light blue, subunit 6) in complex with (c) SylA (green; PDB accession code ) and (d) GlbA (green, aliphatic tail in yellow; PDB accession code ). Magenta, covalent linkage of inhibitors with active site Thr1; dotted lines indicate hydrogen bonds. Black, residues performing specific interactions with SylA and GlbA. Electron-density maps (grey) are contoured from 1 in similar orientations around Thr1. e, Electrostatic potential surface (contoured from +15kT/e (intense blue) to -15kT/e (intense red)) of SylA bound to subunit 5. f, Structural superposition of SylA (green) with GlbA (yellow) bound to subunit 5.