PDBsum entry: 1ct2

Hydrolase/hydrolase inhibitor

PDB-id: 1ct2

Biological unit* = asymmetric unit,
as shown
(*as deduced by PQS)

Contents

Description

Header details

Header records

References

PROCHECK

Protein chains

185 a.a. *

51 a.a. *

Waters ×164

* Residue conservation analysis

Tools

Clefts Calculation

PDB id:

1ct2

Name:

Hydrolase/hydrolase inhibitor

Title:

Crystal structure of the omtky3 p1 variant omtky3-thr18i in complex with sgpb

Structure:

Proteinase b. Chain: e. Synonym: sgpb. Ovomucoid inhibitor. Chain: i. Fragment: third domain omtky3-thr18i. Engineered: yes. Mutation: yes

Source:

Streptomyces griseus. Organism_taxid: 1911. Strain: k1. Meleagris gallopavo. Turkey. Organism_taxid: 9103. Cell: egg. Expressed in: escherichia coli. Expression_system_taxid: 562.

Biological unit:

Dimer (from PQS)

UniProt:

Chain E: P00777 (PRTB_STRGR)

Seq:
Struc:
	Seq:	299 a.a.
	Struc:	185 a.a.*

Chain I: P68390 (IOVO_MELGA)

Seq:

185 a.a.

Struc:

51 a.a.*

Key:	PfamA domain
Secondary structure	CATH domain

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

Enzyme class:

Chain E: E.C.3.4.21.81   [IntEnz]   [ExPASy]   [KEGG]   [BRENDA]

Reaction:

Hydrolysis of proteins with specificity similar to trypsin.

Resolution:

1.65Å

R-factor:

0.169

Authors:

K.S.Bateman,S.Anderson,W.Lu,M.A.Qasim,M.Laskowski Jr., M.N.James

Key ref:

K.S.Bateman et al. (2000). Deleterious effects of beta-branched residues in the S1 specificity pocket of Streptomyces griseus proteinase B (SGPB): crystal structures of the turkey ovomucoid third domain variants Ile18I, Val18I, Thr18I, and Ser18I in complex with SGPB.. Protein Sci, 9, 83-94. [PubMed id: 10739250]

Date:

18-Aug-99

Release date:

12-Jan-00

Related entries:

3sgb
3sgb contains the wild type omtky3 in complex with sgpb
1sgr
1sgr contains recombinant omtky3 (del 1-5) in complex with
sgpb
1sgq
1sgq contains omtky3 p1 variant omtky3-gly18i in complex
with sgpb
1sgp
1sgp contains omtky3 p1 variant omtky3-ala18i in complex
... plus others (see Header records)

Quick_links

Procheck

Clefts

Surface

Key reference

Full text	Protein Sci 9:83-94 (2000)
PubMed id: 10739250

Deleterious effects of beta-branched residues in the S1 specificity pocket of Streptomyces griseus proteinase B (SGPB): crystal structures of the turkey ovomucoid third domain variants Ile18I, Val18I, Thr18I, and Ser18I in complex with SGPB.

K.S.Bateman, S.Anderson, W.Lu, M.A.Qasim, M.Laskowski, M.N.James.

ABSTRACT

Turkey ovomucoid third domain (OMTKY3) is a canonical inhibitor of serine proteinases. Upon complex formation, the inhibitors fully exposed P1 residue becomes fully buried in the preformed cavity of the enzyme. All 20 P1 variants of OMTKY3 have been obtained by recombinant DNA technology and their equilibrium association constants have been measured with six serine proteinases. To rationalize the trends observed in this data set, high resolution crystal structures have been determined for OMTKY3 P1 variants in complex with the bacterial serine proteinase, Streptomyces griseus proteinase B (SGPB). Four high resolution complex structures are being reported in this paper; the three beta-branched variants, Ile18I, Val18I, and Thr18I, determined to 2.1, 1.6, and 1.7 A resolution, respectively, and the structure of the Ser18I variant complex, determined to 1.9 A resolution. Models of the Cys18I, Hse18I, and Ape18I variant complexes are also discussed. The beta-branched side chains are not complementary to the shape of the S1 binding pocket in SGPB, in contrast to that of the wild-type gamma-branched P1 residue for OMTKY3, Leu18I. Chi1 angles of approximately 40 degrees are imposed on the side chains of Ile18I, Val18I, and Thr18I within the S1 pocket. Dihedral angles of +60 degrees, -60 degrees, or 180 degrees are more commonly observed but 40 degrees is not unfavorable for the beta-branched side chains. Thr18I Ogamma1 also forms a hydrogen bond with Ser195 Ogamma in this orientation. The Ser18I side chain adopts two alternate conformations within the S1 pocket of SGPB, suggesting that the side chain is not stable in either conformation.