Use of a "silver bullet" to resolve crystal lattice dislocation disorder: a cobalamin complex of Δ1-pyrroline-5-carboxylate dehydrogenase from Mycobacterium tuberculosis

J Struct Biol. 2015 Feb;189(2):153-7. doi: 10.1016/j.jsb.2014.12.007. Epub 2014 Dec 31.


The use of small molecules as "silver bullets" that can bind to generate crosslinks between protein molecules has been advanced as a powerful means of enhancing success in protein crystallization (McPherson and Cudney, 2006). We have explored this approach in attempts to overcome an order-disorder phenomenon that complicated the structural analysis of the enzyme Δ(1)-pyrroline-5-carboxylate dehydrogenase from Mycobacterium tuberculosis (P5CDH, Mtb-PruA). Using the Silver Bullets Bio screen, we obtained new crystal packing using cobalamin as a co-crystallization agent. This crystal form did not display the order-disorder phenomenon previously encountered. Solution of the crystal structure showed that cobalamin molecules are present in the crystal contacts. Although the cobalamin binding probably does not have physiological relevance, it reflects similarities in the nucleotide-binding region of Mtb-PruA, with the nucleotide loop of cobalamin sharing the binding site for the adenine moiety of NAD(+).

Keywords: Cobalamin binding; Crystal structure; Protein crystallization.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • 1-Pyrroline-5-Carboxylate Dehydrogenase / chemistry*
  • Bacterial Proteins / chemistry*
  • Catalytic Domain
  • Cross-Linking Reagents / chemistry*
  • Crystallization
  • Crystallography, X-Ray
  • Hydrogen Bonding
  • Kinetics
  • Models, Molecular
  • Mycobacterium tuberculosis / enzymology*
  • NAD / chemistry
  • Protein Structure, Quaternary
  • Vitamin B 12 / chemistry*


  • Bacterial Proteins
  • Cross-Linking Reagents
  • NAD
  • 1-Pyrroline-5-Carboxylate Dehydrogenase
  • Vitamin B 12

Associated data

  • PDB/4LEM
  • PDB/4NS3