PDBsum entry 2olg

Hydrolase

PDB id: 2olg

Contents

Protein chain

276 a.a. *

Ligands

NAG

SO4

Metals

_CA

Waters ×128

* Residue conservation analysis

PDB id:

2olg

Name:

Hydrolase

Title:

Crystal structure of the serine protease domain of prophenoloxidase activating factor-i in a zymogen form

Structure:

Pro-phenoloxidase activating enzyme-i. Chain: a. Fragment: serine protease domain, residues 88-365. Engineered: yes

Source:

Holotrichia diomphalia. Organism_taxid: 33394. Expressed in: spodoptera frugiperda. Expression_system_taxid: 7108. Expression_system_cell_line: sf9.

Resolution:

1.70Å R-factor: 0.208 R-free: 0.245

Authors:

N.C.Ha,S.Piao

Key ref:

S.Piao et al. (2007). Crystal structure of the serine protease domain of prophenoloxidase activating factor-I. J Biol Chem, 282, 10783-10791. PubMed id: 17287215 DOI: 10.1074/jbc.M611556200

Date:

19-Jan-07 Release date: 06-Feb-07

Protein chain

O97366  (PPAF1_HOLDI) -  Phenoloxidase-activating factor 1 from Holotrichia diomphalia

Seq: 365 a.a.

Struc: 276 a.a.

Enzyme reactions

• Enzyme class: E.C.3.4.21.- - ?????

DOI no: 10.1074/jbc.M611556200

J Biol Chem 282:10783-10791 (2007)

PubMed id: 17287215

Crystal structure of the serine protease domain of prophenoloxidase activating factor-I.

S.Piao, S.Kim, J.H.Kim, J.W.Park, B.L.Lee, N.C.Ha.

ABSTRACT

A family of serine proteases (SPs) mediates the proteolytic cascades of embryonic development and immune response in invertebrates. These proteases, called easter-type SPs, consist of clip and chymotrypsin-like SP domains. The SP domain of easter-type proteases differs from those of typical SPs in its primary structure. Herein, we report the first crystal structure of the SP domain of easter-type proteases, presented as that of prophenoloxidase activating factor (PPAF)-I in zymogen form. This structure reveals several important structural features including a bound calcium ion, an additional loop with a unique disulfide linkage, a canyon-like deep active site, and an exposed activation loop. We subsequently show the role of the bound calcium and the proteolytic susceptibility of the activation loop, which occurs in a clip domain-independent manner. Based on biochemical study in the presence of heparin, we suggest that PPAF-III, highly homologous to PPAF-I, contains a surface patch that is responsible for enhancing the catalytic activity through interaction with a nonsubstrate region of a target protein. These results provide insights into an activation mechanism of easter-type proteases in proteolytic cascades, in comparison with the well studied blood coagulation enzymes in mammals.

Selected figure(s)

Figure 2.
Overall structure of the SP domain of PPAF-I, shown in standard orientation (32). A, a ribbon representation of the PPAF-I SP domain structure. The SP domain is shown in cyan, except for several loop regions whose color scheme is as described in the legend to Fig. 1. Bound calcium ion is in green, and the three disulfide bonds are drawn with sulfur atoms in yellow. The catalytic triad residues (Ser-His-Asp) are shown in the ball-and-stick representation. Asn-131 (c36) in 30-loop is N-linked glycosylated. B, left, the superimposed Cα traces of the PPAF-I SP domain (cyan) and chymotrypsinogen (orange; PDB code 1CGI). Right, the superimposed Cα traces of the PPAF-I SP domain (cyan) and PPAF-II SP domain (gray; PDB code 2B9L).

Figure 6.
The canyon-like deep active-site cleft.A, a side view of the active site from the right of the molecule in Fig. 2A. The coloring scheme is as in Fig. 2A. The ionic interaction between Arg-160 and Glu-263 is shown as a dotted line. B, surface representation of PPAF-I is shown with a Cα worm. The region and orientation of the molecule are similar to those in Fig. 4A. The surface representation was generated from a virtual mutant molecule (R160A/E263A), and it was perpendicularly clipped just before the catalytic serine residue for clarity. The distance between Arg-160 and the O-γ of Ser-315 is 11.1 Å as shown.

The above figures are reprinted by permission from the ASBMB: J Biol Chem (2007, 282, 10783-10791) copyright 2007.

Figures were selected by an automated process.