PDBsum entry 1g0v

Hydrolase/hydrolase inhibitor

PDB id: 1g0v

Contents

Protein chains

329 a.a. *

29 a.a. *

Ligands

NAG-NAG-BMA-MAN-MAN-BMA-MAN-MAN

MAN

NAG

Waters ×229

* Residue conservation analysis

PDB id:

1g0v

Name:

Hydrolase/hydrolase inhibitor

Title:

The structure of proteinase a complexed with a ia3 mutant, mvv

Structure:

Proteinase a. Chain: a. Synonym: saccharopepsin precursor, aspartate protease, proteinase ysca. Engineered: yes. Protease a inhibitor 3. Chain: b. Fragment: mvv, a mutant of ia3. Synonym: cytoplasmic inhibitor of proteinase pep4p.

Source:

Saccharomyces cerevisiae. Baker's yeast. Organism_taxid: 4932. Expressed in: escherichia coli. Expression_system_taxid: 562. Synthetic: yes

Biol. unit:

Tetramer (from PQS)

Resolution:

2.00Å R-factor: 0.198 R-free: 0.231

Authors:

L.H.Phylip,W.Lees,B.G.Brownsey,D.Bur,B.M.Dunn,J.Winther,A.Gustchina, M.Li,T.Copeland,A.Wlodawer,J.Kay

Key ref:

L.H.Phylip et al. (2001). The potency and specificity of the interaction between the IA3 inhibitor and its target aspartic proteinase from Saccharomyces cerevisiae. J Biol Chem, 276, 2023-2030. PubMed id: 11042188 DOI: 10.1074/jbc.M008520200

Date:

09-Oct-00 Release date: 21-Apr-01

Protein chain

P07267  (CARP_YEAST) -  Saccharopepsin from Saccharomyces cerevisiae (strain ATCC 204508 / S288c)

Seq: 405 a.a.

Struc: 329 a.a.*

Protein chain

P01094  (IPA3_YEAST) -  Protease A inhibitor 3 from Saccharomyces cerevisiae (strain ATCC 204508 / S288c)

Seq: 68 a.a.

Struc: 29 a.a.*

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

Enzyme reactions

• Enzyme class: Chain A: E.C.3.4.23.25 - saccharopepsin.
• Reaction: Hydrolysis of proteins with broad specificity for peptide bonds. Cleaves -Leu-Leu-|-Val-Tyr- bond in a synthetic substrate. Does not act on esters of Tyr or Arg.

DOI no: 10.1074/jbc.M008520200

J Biol Chem 276:2023-2030 (2001)

PubMed id: 11042188

The potency and specificity of the interaction between the IA3 inhibitor and its target aspartic proteinase from Saccharomyces cerevisiae.

L.H.Phylip, W.E.Lees, B.G.Brownsey, D.Bur, B.M.Dunn, J.R.Winther, A.Gustchina, M.Li, T.Copeland, A.Wlodawer, J.Kay.

ABSTRACT

The yeast IA3 polypeptide consists of only 68 residues, and the free inhibitor has little intrinsic secondary structure. IA3 showed subnanomolar potency toward its target, proteinase A from Saccharomyces cerevisiae, and did not inhibit any of a large number of aspartic proteinases with similar sequences/structures from a wide variety of other species. Systematic truncation and mutagenesis of the IA3 polypeptide revealed that the inhibitory activity is located in the N-terminal half of the sequence. Crystal structures of different forms of IA3 complexed with proteinase A showed that residues in the N-terminal half of the IA3 sequence became ordered and formed an almost perfect alpha-helix in the active site of the enzyme. This potent, specific interaction was directed primarily by hydrophobic interactions made by three key features in the inhibitory sequence. Whereas IA3 was cut as a substrate by the nontarget aspartic proteinases, it was not cleaved by proteinase A. The random coil IA3 polypeptide escapes cleavage by being stabilized in a helical conformation upon interaction with the active site of proteinase A. This results, paradoxically, in potent selective inhibition of the target enzyme.

Selected figure(s)

Figure 2.
Fig. 2. Stereo representation of the interactions made by the side chains of Val8 and Phe^12 in the IA[3] polypeptide with cognate hydrophobic residues in proteinase A. Proteinase A residues are green while the Val8 and Phe^12 side chains and the appropriate segment of the IA[3] helical backbone are in brown.

Figure 3.
Fig. 3. Stereo representation of the interactions made by the ~Lys18-Leu19-X-X-Asp22~ centerpiece residues of IA[3] in the vicinity of the active site of proteinase A. Proteinase A residues are in green with the catalytic water molecule depicted as a blue sphere. The side chains of Lys18, Leu19, and Asp22 plus the relevant segment of the IA[3] helix backbone are in brown. Hydrogen bonding distances are shown.

The above figures are reprinted by permission from the ASBMB: J Biol Chem (2001, 276, 2023-2030) copyright 2001.

Figures were selected by an automated process.