Crystallographic studies evidencing the high energy tolerance to disrupting the interface disulfide bond of thioredoxin 1 from white leg shrimp Litopenaeus vannamei

Molecules. 2014 Dec 15;19(12):21113-26. doi: 10.3390/molecules191221113.

Abstract

Thioredoxin (Trx) is a small 12-kDa redox protein that catalyzes the reduction of disulfide bonds in proteins from different biological systems. A recent study of the crystal structure of white leg shrimp thioredoxin 1 from Litopenaeus vannamei (LvTrx) revealed a dimeric form of the protein mediated by a covalent link through a disulfide bond between Cys73 from each monomer. In the present study, X-ray-induced damage in the catalytic and the interface disulfide bond of LvTrx was studied at atomic resolution at different transmission energies of 8% and 27%, 12.8 keV at 100 K in the beamline I-24 at Diamond Light Source. We found that at an absorbed dose of 32 MGy, the X-ray induces the cleavage of the disulfide bond of each catalytic site; however, the interface disulfide bond was cleaved at an X-ray adsorbed dose of 85 MGy; despite being the most solvent-exposed disulfide bond in LvTrx (~50 Å2). This result clearly established that the interface disulfide bond is very stable and, therefore, less susceptible to being reduced by X-rays. In fact, these studies open the possibility of the existence in solution of a dimeric LvTrx.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Arthropod Proteins / chemistry*
  • Catalytic Domain
  • Crystallography, X-Ray
  • Cystine / chemistry*
  • Enzyme Stability
  • Models, Molecular
  • Molecular Sequence Data
  • Penaeidae / enzymology
  • Protein Structure, Secondary
  • Thioredoxins / chemistry*

Substances

  • Arthropod Proteins
  • Cystine
  • Thioredoxins

Associated data

  • PDB/4AJ6
  • PDB/4AJ7
  • PDB/4AJ8