PDBsum entry 1zjk

Hydrolase

PDB id: 1zjk

Contents

Protein chain

390 a.a. *

Waters ×84

* Residue conservation analysis

PDB id:

1zjk

Name:

Hydrolase

Title:

Crystal structure of the zymogen catalytic region of human masp-2

Structure:

Mannan-binding lectin serine protease 2. Chain: a. Fragment: complement control protein modules 1,2 and serine protease domain. Synonym: mannose-binding protein associated serine protease 2, masp- 2, mbl- associated serine protease 2. Engineered: yes. Mutation: yes

Source:

Homo sapiens. Human. Organism_taxid: 9606. Gene: masp2. Expressed in: escherichia coli bl21(de3). Expression_system_taxid: 469008.

Resolution:

2.18Å R-factor: 0.207 R-free: 0.253

Authors:

P.Gal,V.Harmat,A.Kocsis,T.Bian,L.Barna,G.Ambrus,B.Vegh,J.Balczer, R.B.Sim,G.Naray-Szabo,P.Zavodszky

Key ref:

P.Gál et al. (2005). A true autoactivating enzyme. Structural insight into mannose-binding lectin-associated serine protease-2 activations. J Biol Chem, 280, 33435-33444. PubMed id: 16040602 DOI: 10.1074/jbc.M506051200

Date:

29-Apr-05 Release date: 26-Jul-05

Protein chain

O00187  (MASP2_HUMAN) -  Mannan-binding lectin serine protease 2 from Homo sapiens

Seq: 686 a.a.

Struc: 390 a.a.*

* PDB and UniProt seqs differ at 3 residue positions (black crosses)

Enzyme reactions

• Enzyme class: E.C.3.4.21.104 - mannan-binding lectin-associated serine protease-2.

DOI no: 10.1074/jbc.M506051200

J Biol Chem 280:33435-33444 (2005)

PubMed id: 16040602

A true autoactivating enzyme. Structural insight into mannose-binding lectin-associated serine protease-2 activations.

P.Gál, V.Harmat, A.Kocsis, T.Bián, L.Barna, G.Ambrus, B.Végh, J.Balczer, R.B.Sim, G.Náray-Szabó, P.Závodszky.

ABSTRACT

Few reports have described in detail a true autoactivation process, where no extrinsic cleavage factors are required to initiate the autoactivation of a zymogen. Herein, we provide structural and mechanistic insight into the autoactivation of a multidomain serine protease: mannose-binding lectin-associated serine protease-2 (MASP-2), the first enzymatic component in the lectin pathway of complement activation. We characterized the proenzyme form of a MASP-2 catalytic fragment encompassing its C-terminal three domains and solved its crystal structure at 2.4 A resolution. Surprisingly, zymogen MASP-2 is capable of cleaving its natural substrate C4, with an efficiency about 10% that of active MASP-2. Comparison of the zymogen and active structures of MASP-2 reveals that, in addition to the activation domain, other loops of the serine protease domain undergo significant conformational changes. This additional flexibility could play a key role in the transition of zymogen MASP-2 into a proteolytically active form. Based on the three-dimensional structures of proenzyme and active MASP-2 catalytic fragments, we present model for the active zymogen MASP-2 complex and propose a mechanism for the autoactivation process.

Selected figure(s)

Figure 3.
FIGURE 3. Cleavage of C4 by MASP-2 CCP1-CCP2-SP R444Q mutant. Incubation times are indicated in minutes. The and chains of C4 and the digestion product, ', are indicated by the arrows.

Figure 8.
FIGURE 8. Schematic diagram of the proposed autoactivation mechanism of MASP-2. The CCP1-CCP2 moiety is shown as dotted ellipses, and the SP domain is shown as a gray blob with the activation peptide represented as a black loop. The flexible CCP2/SP junction helps in orienting the SP domains (gray arrows) in the physiological MBL ·MASP-2 complex. A, during "step 1" the zymogen molecule (left) cleaves another zymogen molecule (right). In their initial complex, in addition to favorable contacts (white arrows), unfavorable interactions (black arrows) are also present, and the inactive/active-like conformational transition of the enzyme SP domain (from light gray to gray striped) is promoted. After the enzyme reaction, the product (dark gray SP) is released. B, during "step 2," the activated (left, dark gray SP) and zymogen (right, light gray SP) MASP-2 play the roles of the enzyme and the substrate, respectively. In contrast to step 1, here the binding surface of the enzyme and the substrate is preformed to make the canonical Michaelis complex prior to the enzyme reaction.

The above figures are reprinted by permission from the ASBMB: J Biol Chem (2005, 280, 33435-33444) copyright 2005.

Figures were selected by an automated process.