3m86

Crystal structure of the cysteine protease inhibitor, EhICP2, from Entamoeba histolytica

spinqualitylabelsall models 3m86, resolution 1.65Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 3m86 is a 2 chain structure with sequence from Entamoeba histolytica hm-1:imss. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Ligands: 1PE, CL, SO4 Related: 3m88 Gene: EHI_040460, ICP2 (Entamoeba histolytica HM-1:IMSS) Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Publication Abstract from PubMed Cysteine proteases (CP) are key pathogenesis and virulence determinants of protozoan parasites. Entamoeba histolytica contains at least 50 cysteine proteases; however, only three (EhCP1, EhCP2 and EhCP5) are responsible for approximately 90% of the cysteine protease activity in this parasite. CPs are expressed as inactive zymogens. Because the processed proteases are potentially cytotoxic, protozoan parasites have developed mechanisms to regulate their activity. Inhibitors of cysteine proteases (ICP) of the chagasin-like inhibitor family (MEROPS family I42) were recently identified in bacteria and protozoan parasites. E. histolytica contains two ICP-encoding genes of the chagasin-like inhibitor family. EhICP1 localizes to the cytosol, whereas EhICP2 is targeted to phagosomes. Herein, we report two crystal structures of EhICP2. The overall structure of EhICP2 consists of eight beta-strands and closely resembles the immunoglobulin fold. A comparison between the two crystal forms of EhICP2 indicates that the conserved BC, DE and FG loops form a flexible wedge that may block the active site of CPs. The positively charged surface of the wedge-forming loops in EhICP2 contrasts with the neutral surface of the wedge-forming loops in chagasin. We postulate that the flexibility and positive charge observed in the DE and FG loops of EhICP2 may be important to facilitate the initial binding of this inhibitor to the battery of CPs present in E. histolytica. Crystal structure of the cysteine protease inhibitor 2 from Entamoeba histolytica: functional convergence of a common protein fold.,Casados-Vazquez LE, Lara-Gonzalez S, Brieba LG Gene. 2011 Jan 15;471(1-2):45-52. Epub 2010 Oct 15. PMID:20951777 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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