PDBsum entry 1mtp

Structural genomics

PDB id: 1mtp

Contents

Protein chains

320 a.a. *

35 a.a. *

Waters ×604

* Residue conservation analysis

PDB id:

1mtp

Name:

Structural genomics

Title:

The x-ray crystal structure of a serpin from a thermophilic prokaryote

Structure:

Serine proteinase inhibitor (serpin), chain a. Chain: a. Fragment: chain a, residue 55-377. Engineered: yes. Serine proteinase inhibitor (serpin), chain b. Chain: b. Fragment: chain b, residue 378-420. Engineered: yes

Source:

Thermobifida fusca. Organism_taxid: 2021. Expressed in: escherichia coli. Expression_system_taxid: 562. Expression_system_taxid: 562

Biol. unit:

Dimer (from PQS)

Resolution:

1.50Å R-factor: 0.195 R-free: 0.223

Authors:

J.A.Irving,L.D.Cabrita,J.Rossjohn,R.N.Pike,S.P.Bottomley, J.C.Whisstock

Key ref:

J.A.Irving et al. (2003). The 1.5 A crystal structure of a prokaryote serpin: controlling conformational change in a heated environment. Structure, 11, 387-397. PubMed id: 12679017 DOI: 10.1016/S0969-2126(03)00057-1

Date:

21-Sep-02 Release date: 15-Apr-03

Protein chain

Q47NK3  (Q47NK3_THEFY) -  Proteinase inhibitor I4, serpin from Thermobifida fusca (strain YX)

Seq: 366 a.a.

Struc: 320 a.a.*

Protein chain

Q47NK3  (Q47NK3_THEFY) -  Proteinase inhibitor I4, serpin from Thermobifida fusca (strain YX)

Seq: 366 a.a.

Struc: 35 a.a.

* PDB and UniProt seqs differ at 5 residue positions (black crosses)

Enzyme reactions

• Enzyme class: Chains A, B: E.C.?

DOI no: 10.1016/S0969-2126(03)00057-1

Structure 11:387-397 (2003)

PubMed id: 12679017

The 1.5 A crystal structure of a prokaryote serpin: controlling conformational change in a heated environment.

J.A.Irving, L.D.Cabrita, J.Rossjohn, R.N.Pike, S.P.Bottomley, J.C.Whisstock.

ABSTRACT

Serpins utilize conformational change to inhibit target proteinases; the price paid for this conformational flexibility is that many undergo temperature-induced polymerization. Despite this thermolability, serpins are present in the genomes of thermophilic prokaryotes, and here we characterize the first such serpin, thermopin. Thermopin is a proteinase inhibitor and, in comparison with human alpha(1)-antitrypsin, possesses enhanced stability at 60 degrees C. The 1.5 A crystal structure reveals novel structural features in regions implicated in serpin folding and stability. Thermopin possesses a C-terminal "tail" that interacts with the top of the A beta sheet and plays an important role in the folding/unfolding of the molecule. These data provide evidence as to how this unusual serpin has adapted to fold and function in a heated environment.

Selected figure(s)

Figure 1.
Figure 1. A Schematic Summarizing the Inhibitory Mechanism of SerpinsThe RCL is the region responsible for interacting with target proteinases and is at the top of the molecule. Residues within the RCL are numbered according to Schecter and Berger [78], in which the residues of a peptide substrate are designated P[n]...P[2], P[1], and P[1]'...P[n]', and interact with corresponding subsites in the proteinase, designated S[n]...S[2], S[1], and S[1]'...S[n]'; cleavage occurs by definition between the P[1] and P[1]' positions. The proteinase (denoted by "P") recognizes the RCL sequence and cleaves the serpin between P[1] and P[1]'; after this, prior to hydrolysis of the acyl bond that links enzyme to inhibitor, the RCL inserts into the central "A" b sheet. The proteinase is thereby translocated to the distal end of the molecule, where it is compressed against the base of the serpin and its active site is distorted.

The above figure is reprinted by permission from Cell Press: Structure (2003, 11, 387-397) copyright 2003.

Figure was selected by an automated process.