PDBsum entry 1y1k

Hydrolase/hydrolase inhibitor

PDB id: 1y1k

Contents

Protein chains

281 a.a. *

64 a.a. *

Ligands

CIT ×3

15P ×3

Metals

_CA

_NA

Waters ×499

* Residue conservation analysis

PDB id:

1y1k

Name:

Hydrolase/hydrolase inhibitor

Title:

Crystal structure of the complex of subtilisin bpn' with chymotrypsin inhibitor 2 t58a mutant

Structure:

Subtilisin bpn'. Chain: e. Synonym: subtilisin novo. Subtilisin dfe. Alkaline protease. Engineered: yes. Mutation: yes. Chymotrypsin inhibitor 2. Chain: i. Engineered: yes. Mutation: yes

Source:

Bacillus amyloliquefaciens. Organism_taxid: 1390. Gene: apr. Expressed in: bacillus subtilis. Expression_system_taxid: 1423. Hordeum vulgare. Organism_taxid: 4513. Expressed in: escherichia coli bl21(de3). Expression_system_taxid: 469008.

Biol. unit:

Dimer (from PQS)

Resolution:

1.56Å R-factor: 0.165 R-free: 0.185

Authors:

E.S.Radisky,C.J.Lu,G.Kwan,D.E.Koshland Jr.

Key ref:

E.S.Radisky et al. (2005). Role of the intramolecular hydrogen bond network in the inhibitory power of chymotrypsin inhibitor 2. Biochemistry, 44, 6823-6830. PubMed id: 15865427 DOI: 10.1021/bi047301w

Date:

18-Nov-04 Release date: 17-May-05

Protein chain

P00782  (SUBT_BACAM) -  Subtilisin BPN' from Bacillus amyloliquefaciens

Seq: 382 a.a.

Struc: 281 a.a.

Protein chain

Q40059  (Q40059_HORVU) -  Chymotrypsin inhibitor 2 from Hordeum vulgare

Seq: 84 a.a.

Struc: 64 a.a.*

* PDB and UniProt seqs differ at 2 residue positions (black crosses)

Enzyme reactions

• Enzyme class: Chain E: E.C.3.4.21.62 - subtilisin.
• Reaction: Hydrolysis of proteins with broad specificity for peptide bonds, and a preference for a large uncharged residue in P1. Hydrolyzes peptide amides.

DOI no: 10.1021/bi047301w

Biochemistry 44:6823-6830 (2005)

PubMed id: 15865427

Role of the intramolecular hydrogen bond network in the inhibitory power of chymotrypsin inhibitor 2.

E.S.Radisky, C.J.Lu, G.Kwan, D.E.Koshland.

ABSTRACT

A series of mutants of chymotrypsin inhibitor 2 (CI2), at residues involved in intramolecular interactions that shape and constrain the binding loop, were studied to determine their relative importance for inhibition of the serine protease subtilisin BPN', and for resistance of the inhibitor to proteolysis. These functional properties were investigated in tandem with the crystal structures of the mutant inhibitor-enzyme complexes. A dense hydrogen bonding network that supports the binding loop in the vicinity of the scissile bond was found to be important both for enzyme affinity and for stability to proteolysis. Structural analysis, in combination with biochemical measurements, allows differentiation of the structural components most important for resistance to proteolysis and/or binding. The most critical participating residues in the network were found to be Thr-58, Glu-60, Arg-65, and Gly-83. Glu-60 is more important for resistance to proteolysis than for binding, while Arg-65 and two other Arg residues play a greater role in binding than in resistance to proteolysis. Structural comparisons reveal a wide variety of subtle conformational changes in response to mutation, with built-in robustness in the hydrogen bond network, such that loss of one contact is compensated by other new contacts.