Bar graphs showing the inhibitor-induced shifts to the closed state, Δc%, with inhibitors for PR natural variants (B, PR5, C and CRF_01A/E), drug-resistant construct (MDR769) and clinical isolates (V6). The relative shift of the closed state is calculated as Δc% = [percentage closed (inhibitor)] – [percentage closed (apo)]. The magenta and red lines correspond to the arbitrary cut-offs to designate weak (<20%), strong (>50%) and moderate (20%< Δc%< 50%) effects of inhibitors on shifting the conformational ensemble.