PDBsum entry 4dg4

Hydrolase/hydrolase inhibitor

PDB id: 4dg4

Contents

Protein chains

224 a.a.

58 a.a.

Ligands

SO4 ×24

Metals

_CA

Waters ×1322

PDB id:

4dg4

Name:

Hydrolase/hydrolase inhibitor

Title:

Human mesotrypsin-s39y complexed with bovine pancreatic trypsin inhibitor (bpti)

Structure:

Prss3 protein. Chain: a, b, d, g. Fragment: unp residues 28-251. Engineered: yes. Mutation: yes. Pancreatic trypsin inhibitor. Chain: e, c, f, h. Fragment: unp residues 36-93. Synonym: aprotinin, basic protease inhibitor, bpi, bpti.

Source:

Homo sapiens. Human. Organism_taxid: 9606. Gene: prss3. Expressed in: escherichia coli. Expression_system_taxid: 562. Bos taurus. Domestic cattle. Organism_taxid: 9913.

Resolution:

1.40Å R-factor: 0.166 R-free: 0.211

Authors:

M.A.Salameh,A.S.Soares,E.S.Radisky

Key ref:

M.A.Salameh et al. (2012). Presence versus absence of hydrogen bond donor Tyr-39 influences interactions of cationic trypsin and mesotrypsin with protein protease inhibitors. Protein Sci, 21, 1103-1112. PubMed id: 22610453

Date:

24-Jan-12 Release date: 12-Sep-12

Protein chains

P35030  (TRY3_HUMAN) -  Trypsin-3 from Homo sapiens

Seq: 304 a.a.

Struc: 224 a.a.*

Protein chains

P00974  (BPT1_BOVIN) -  Pancreatic trypsin inhibitor from Bos taurus

Seq: 100 a.a.

Struc: 58 a.a.

* PDB and UniProt seqs differ at 3 residue positions (black crosses)

Enzyme reactions

• Enzyme class: Chains A, B, D, G: E.C.3.4.21.4 - trypsin.
• Reaction: Preferential cleavage: Arg-|-Xaa, Lys-|-Xaa.

Protein Sci 21:1103-1112 (2012)

PubMed id: 22610453

Presence versus absence of hydrogen bond donor Tyr-39 influences interactions of cationic trypsin and mesotrypsin with protein protease inhibitors.

M.A.Salameh, A.S.Soares, A.Alloy, E.S.Radisky.

ABSTRACT

Mesotrypsin displays unusual resistance to inhibition by polypeptide trypsin inhibitors and cleaves some such inhibitors as substrates, despite a high degree of conservation with other mammalian trypsins. Substitution of Arg for the generally conserved Gly-193 has been implicated as a critical determinant of the unusual behavior of mesotrypsin toward protein protease inhibitors. Another relatively conserved residue near the trypsin active site, Tyr-39, is substituted by Ser-39 in mesotrypsin. Tyr-39, but not Ser-39, forms a hydrogen bond with the main chain amide nitrogen of the P(4) ' residue of a bound protease inhibitor. To investigate the role of the Tyr-39 H-bond in trypsin-inhibitor interactions, we reciprocally mutated position 39 in mesotrypsin and human cationic trypsin to Tyr-39 and Ser-39, respectively. We assessed inhibition constants and cleavage rates of canonical protease inhibitors bovine pancreatic trypsin inhibitor (BPTI) and the amyloid precursor protein Kunitz protease inhibitor domain by mesotrypsin and cationic trypsin variants, finding that the presence of Ser-39 relative to Tyr-39 results in a 4- to 13-fold poorer binding affinity and a 2- to 18-fold increase in cleavage rate. We also report the crystal structure of the mesotrypsin-S39Y•BPTI complex, in which we observe an H-bond between Tyr-39 OH and BPTI Ile-19 N. Our results indicate that the presence of Ser-39 in mesotrypsin, and corresponding absence of a single H-bond to the inhibitor backbone, makes a small but significant functional contribution to the resistance of mesotrypsin to inhibition and the ability of mesotrypsin to proteolyze inhibitors.