PDBsum entry 1k9o

Hydrolase/hydrolase inhibitor

PDB id: 1k9o

Contents

Protein chains

376 a.a. *

223 a.a. *

Waters ×182

* Residue conservation analysis

PDB id:

1k9o

Name:

Hydrolase/hydrolase inhibitor

Title:

Crystal structure of michaelis serpin-trypsin complex

Structure:

Alaserpin. Chain: i. Synonym: serpin 1. Engineered: yes. Mutation: yes. Trypsin ii anionic. Chain: e. Synonym: pretrypsinogen ii. Engineered: yes.

Source:

Manduca sexta. Tobacco hornworm. Organism_taxid: 7130. Expressed in: escherichia coli. Expression_system_taxid: 562. Rattus norvegicus. Norway rat. Organism_taxid: 10116. Expressed in: saccharomyces cerevisiae.

Biol. unit:

Dimer (from PQS)

Resolution:

2.30Å R-factor: 0.158 R-free: 0.231

Authors:

S.Ye,A.L.Cech,R.Belmares,R.C.Bergstrom,Y.Tong,D.R.Corey,M.R.Kanost, E.J.Goldsmith

Key ref:

S.Ye et al. (2001). The structure of a Michaelis serpin-protease complex. Nat Struct Biol, 8, 979-983. PubMed id: 11685246 DOI: 10.1038/nsb1101-979

Date:

29-Oct-01 Release date: 21-Nov-01

Supersedes:

1i99

Protein chain

P14754  (SERA_MANSE) -  Alaserpin from Manduca sexta

Seq: 392 a.a.

Struc: 376 a.a.*

Protein chain

P00763  (TRY2_RAT) -  Anionic trypsin-2 from Rattus norvegicus

Seq: 246 a.a.

Struc: 223 a.a.*

* PDB and UniProt seqs differ at 4 residue positions (black crosses)

Enzyme reactions

• Enzyme class: Chain E: E.C.3.4.21.4 - trypsin.
• Reaction: Preferential cleavage: Arg-|-Xaa, Lys-|-Xaa.

DOI no: 10.1038/nsb1101-979

Nat Struct Biol 8:979-983 (2001)

PubMed id: 11685246

The structure of a Michaelis serpin-protease complex.

S.Ye, A.L.Cech, R.Belmares, R.C.Bergstrom, Y.Tong, D.R.Corey, M.R.Kanost, E.J.Goldsmith.

ABSTRACT

Serine protease inhibitors (serpins) regulate the activities of circulating proteases. Serpins inhibit proteases by acylating the serine hydroxyl at their active sites. Before deacylation and complete proteolysis of the serpin can occur, massive conformational changes are triggered in the serpin while maintaining the covalent linkage between the protease and serpin. Here we report the structure of a serpin-trypsin Michaelis complex, which we visualized by using the S195A trypsin mutant to prevent covalent complex formation. This encounter complex reveals a more extensive interaction surface than that present in small inhibitor-protease complexes and is a template for modeling other serpin-protease pairs. Mutations of several serpin residues at the interface reduced the inhibitory activity of the serpin. The serine residue C-terminal to the scissile peptide bond is found in a closer than usual interaction with His 57 at the active site of trypsin.

Selected figure(s)

Figure 1.
Figure 1. Overall structure of serpin-protease complex and comparison with other serpins. a, Ribbon diagram of serpin 1B A353K -trypsin S195A complex. RCL is gold; helices of both serpin and trypsin are blue; -sheets A, B and C of the serpin are light, medium and dark magenta, respectively; and -sheets of trypsin S195A are red. b, Superposition of active serpin 1K (PDB code 1SEK) (cyan throughout; red reactive center) with serpin 1B A353K (magenta throughout; gold reactive center). c, Cleaved form of the serpin -1 antitrypsin (PDB code 9API) drawn by BOBSCRIPT31 and rendered by POV-RAY32. The topological switch point at P16 for insertion of the RCL as strand 4A is marked in (b,c).

Figure 3.
Figure 3. Stereo diagram showing interactions between P16 and P8 in RCL (see text).

The above figures are reprinted by permission from Macmillan Publishers Ltd: Nat Struct Biol (2001, 8, 979-983) copyright 2001.

Figures were selected by an automated process.