PDBsum entry 3erb

Hydrolase

PDB id: 3erb

Contents

Protein chain

188 a.a. *

Waters ×197

* Residue conservation analysis

PDB id:

3erb

Name:

Hydrolase

Title:

The crystal structure of c2b, a fragment of complement component c2 produced during c3-convertase formation

Structure:

Complement c2. Chain: a. Fragment: complement c2b fragment, n-terminal fragment. Synonym: c3/c5 convertase, complement c2b fragment. Engineered: yes

Source:

Homo sapiens. Human. Organism_taxid: 9606. Expressed in: trichoplusia ni. Expression_system_taxid: 7111. Expression_system_cell_line: high five(bti-tn-5b1-4).

Resolution:

1.80Å R-factor: 0.216 R-free: 0.240

Authors:

S.V.L.Narayan,V.Krishnan

Key ref:

V.Krishnan et al. (2009). The structure of C2b, a fragment of complement component C2 produced during C3 convertase formation. Acta Crystallogr D Biol Crystallogr, 65, 266-274. PubMed id: 19237749 DOI: 10.1107/S0907444909000389

Date:

01-Oct-08 Release date: 10-Mar-09

Protein chain

P06681  (CO2_HUMAN) -  Complement C2 from Homo sapiens

Seq: 752 a.a.

Struc: 188 a.a.

Enzyme reactions

• Enzyme class: E.C.3.4.21.43 - classical-complement-pathway C3/C5 convertase.
• Reaction: Cleaves component C3 at the carboxyl of Arg-77 of the alpha-chain to yield C3a and C3b, and component C5 at the carboxyl of Arg-74 of the alpha-chain to yield C5a and C5b.

DOI no: 10.1107/S0907444909000389

Acta Crystallogr D Biol Crystallogr 65:266-274 (2009)

PubMed id: 19237749

The structure of C2b, a fragment of complement component C2 produced during C3 convertase formation.

V.Krishnan, Y.Xu, K.Macon, J.E.Volanakis, S.V.Narayana.

ABSTRACT

The second component of complement (C2) is a multi-domain serine protease that provides catalytic activity for the C3 and C5 convertases of the classical and lectin pathways of human complement. The formation of these convertases requires the Mg(2+)-dependent binding of C2 to C4b and the subsequent cleavage of C2 by C1s or MASP2, respectively. The crystal structure of full-length C2 is not yet available, although the structure of its C-terminal catalytic segment C2a has been determined. The crystal structure of the N-terminal segment C2b of C2 determined to 1.8 A resolution presented here reveals the arrangement of its three CCP domains. The domains are arranged differently compared with most other CCP-domain assemblies, but their arrangement is similar to that found in the Ba part of the full-length factor B structure. The crystal structures of C2a, C2b and full-length factor B are used to generate a model for C2 and a discussion of the domain association and possible interactions with C4b during formation of the C4b-C2 complex is presented. The results of this study also suggest that upon cleavage by C1s, C2a domains undergo conformational rotation while bound to C4b and the released C2b domains may remain folded together similar to as observed in the intact protein.

Selected figure(s)

Figure 3.
Figure 3 Topology representation of individual CCP domains of C2b. Successive individual -strands are labeled A-H and are colored as in Fig. 2-. Topology representations are shown for (a) a typical CCP domain and the individual CCP domains of C2b: (b) CCP1, (c) CCP2 and (d) CCP3.

Figure 6.
Figure 6 Model of full-length C2 in ribbon representation. The N-terminal CCP1 (red), CCP2 (gold), CCP3 (yellow), CCP3-vWFA linker (blue), vWFA domain (cyan) and SP domain (magenta) are represented and the MIDAS and SP catalytic site are indicated with arrows.

The above figures are reprinted by permission from the IUCr: Acta Crystallogr D Biol Crystallogr (2009, 65, 266-274) copyright 2009.

Figures were selected by an automated process.