PDBsum entry: 1tlo

Hydrolase

PDB id: 1tlo

Contents

Protein chain

322 a.a. *

Ligands

E64

Metals

_CA ×2

Waters ×53

* Residue conservation analysis

PDB id:

1tlo

Name:

Hydrolase

Title:

High resolution crystal structure of calpain i protease core in complex with e64

Structure:

Calpain 1, large [catalytic] subunit. Chain: a. Fragment: residues 27-356. Synonym: calcium-activated neutral proteinase, canp, mu- type, mucanp, micromolar-calpain. Engineered: yes

Source:

Rattus norvegicus. Norway rat. Organism_taxid: 10116. Gene: capn1, cls1. Expressed in: escherichia coli bl21(de3). Expression_system_taxid: 469008.

Resolution:

1.90Å R-factor: 0.238 R-free: 0.272

Authors:

T.Moldoveanu,R.L.Campbell,D.Cuerrier,P.L.Davies

Key ref:

T.Moldoveanu et al. (2004). Crystal structures of calpain-E64 and -leupeptin inhibitor complexes reveal mobile loops gating the active site. J Mol Biol, 343, 1313-1326. PubMed id: 15491615 DOI: 10.1016/j.jmb.2004.09.016

Date:

09-Jun-04 Release date: 02-Nov-04

Protein chain

P97571  (CAN1_RAT) -  Calpain-1 catalytic subunit

Seq: 713 a.a.

Struc: 322 a.a.

Enzyme reactions

• Enzyme class: E.C.3.4.22.52 - Calpain-1.
• Cofactor: Calcium

 Gene Ontology (GO) functional annotation 

• Cellular component: intracellular (1 term)
• Biological process: proteolysis (1 term)
• Biochemical function: cysteine-type endopeptidase activity (2 terms)

DOI no: 10.1016/j.jmb.2004.09.016

J Mol Biol 343:1313-1326 (2004)

PubMed id: 15491615

Crystal structures of calpain-E64 and -leupeptin inhibitor complexes reveal mobile loops gating the active site.

T.Moldoveanu, R.L.Campbell, D.Cuerrier, P.L.Davies.

ABSTRACT

The endogenous calpain inhibitor, calpastatin, modulates some patho-physiological aspects of calpain signaling. Excess calpain can escape this inhibition and as well, many calpain isoforms and autolytically generated protease core fragments are not inhibited by calpastatin. There is a need, therefore, to develop specific, cell-permeable calpain inhibitors to block uncontrolled proteolysis and prevent tissue damage during brain and heart ischemia, spinal-cord injury and Alzheimer's diseases. Here, we report the first high-resolution crystal structures of rat mu-calpain protease core complexed with two traditional, low molecular mass inhibitors, leupeptin and E64. These structures show that access to a slightly deeper, but otherwise papain-like active site is gated by two flexible loops. These loops are divergent among the calpain isoforms giving a potential structural basis for substrate/inhibitor selectivity over other papain-like cysteine proteases and between members of the calpain family.

Selected figure(s)

Figure 4.
Figure 4. Close-up of µI-II-inhibitor interactions. Stereoview of the interactions between leupeptin (green) and E64 (magenta) with calpain µI-II. Residues within domains I and II are colored blue and cyan, respectively. The residues found within 4 Å of leupeptin and E64 are colored by atom type (carbon, yellow; oxygen, red; nitrogen, blue; and sulfur, orange). Hydrogen-bonding interactions are indicated by dotted blue lines. (A) and (B) Surface and stick representations of the calpain µI-II-leupeptin complex. (C) and (D) Stick and surface representations of the calpain µI-II-E64 complex.

Figure 7.
Figure 7. Comparison of calpain's active site with that of papain and cathepsins K and B. (A) Calpain µI-II-leupeptin complex. (B) Papain-leupeptin complex (PDB code 1POP). (C)-(F) Close-up views of active site cleft (rotated about 90° from (A) and (B)). (C) Calpain µI-II-leupeptin. (D) Papain-leupeptin. (E) Cathepsin K-E64 (PDB code 1ATK). (F) Cathepsin B-benzyloxycarbonyl-Arg-Ser(O-Bzl) chloromethylketone (PDB code 1THE45).

The above figures are reprinted by permission from Elsevier: J Mol Biol (2004, 343, 1313-1326) copyright 2004.

Figures were selected by an automated process.