PDBsum entry 4tx4

Hydrolase inhibitor

PDB id: 4tx4

Contents

Protein chains

79 a.a.

83 a.a.

Ligands

SO4

Waters ×157

PDB id:

4tx4

Name:

Hydrolase inhibitor

Title:

Crystal structure of a single-domain cysteine protease inhibitor from cowpea (vigna unguiculata)

Structure:

Cysteine proteinase inhibitor. Chain: b, a. Fragment: unp residues 15-97. Synonym: cystatin. Engineered: yes

Source:

Vigna unguiculata. Cowpea. Organism_taxid: 3917. Expressed in: escherichia coli. Expression_system_taxid: 469008.

Resolution:

1.95Å R-factor: 0.174 R-free: 0.195

Authors:

H.M.Pereira,N.Valadares,J.E.Monteiro-Junior,C.P.S.Carvalho, T.B.Grangeiro

Key ref:

J.E.Monteiro Júnior et al. (2017). Expression in Escherichia coli of cysteine protease inhibitors from cowpea (Vigna unguiculata): The crystal structure of a single-domain cystatin gives insights on its thermal and pH stability. Int J Biol Macromol, 102, 29-41. PubMed id: 28389401 DOI: 10.1016/j.ijbiomac.2017.04.008

Date:

02-Jul-14 Release date: 14-Oct-15

Protein chain

Q06445  (CYTI_VIGUN) -  Cysteine proteinase inhibitor from Vigna unguiculata

Seq: 97 a.a.

Struc: 79 a.a.

Protein chain

Q06445  (CYTI_VIGUN) -  Cysteine proteinase inhibitor from Vigna unguiculata

Seq: 97 a.a.

Struc: 83 a.a.

DOI no: 10.1016/j.ijbiomac.2017.04.008

Int J Biol Macromol 102:29-41 (2017)

PubMed id: 28389401

Expression in Escherichia coli of cysteine protease inhibitors from cowpea (Vigna unguiculata): The crystal structure of a single-domain cystatin gives insights on its thermal and pH stability.

J.E.Monteiro Júnior, N.F.Valadares, H.D.Pereira, F.H.Dyszy, A.J.da Costa Filho, A.F.Uchôa, A.S.de Oliveira, C.P.da Silveira Carvalho, T.B.Grangeiro.

ABSTRACT

Two cysteine proteinase inhibitors from cowpea, VuCys1 and VuCys2, were produced in E. coli ArcticExpress (DE3). The recombinant products strongly inhibited papain and chymopapain as well as the midgut proteases from Callosobruchus maculatus larvae, a bruchid that uses cysteine proteases as major digestive enzymes. Heat treatment at 100°C for up to 60min or incubation at various pH values caused little reduction in the papain inhibitory activity of both inhibitors. Moreover, minor conformational variations, as probed by circular dichroism spectroscopy, were observed after VuCys1 and VuCys2 were subjected to these treatments. The crystal structure of VuCys1 was determined at a resolution of 1.95Å, revealing a domain-swapped dimer in the asymmetric unit. However, the two lobes of the domain-swapped dimer are positioned closer to each other in VuCys1 in comparison to other similar cystatin structures. Moreover, some polar residues from opposite lobes recruit water molecules, forming a hydrogen bond network that mediates contacts between the lobes, thus generating an extended open interface. Due to the closer distance between the lobes, a small hydrophobic core is also formed, further stabilizing the folded domain-swapped dimer. These structural features might account for the extraordinary thermal and pH stability of VuCys1.