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Updated: Aug 11, 2026

On-Chip Crystallization and Large-Scale Serial Diffraction at Room Temperature
Published on: March 11, 2022
Crystallization and preliminary X-ray characterization of the nitrile reductase QueF: a queuosine-biosynthesis enzyme
Manal A Swairjo1, Robert R Reddy, Bobby Lee
1Department of Chemistry, The Skaggs Institute for Chemical Biology, The Scripps Research Institute, BCC-379, La Jolla, CA 92037, USA. swairjo@scripps.edu
Abstract:
QueF (MW = 19.4 kDa) is a recently characterized nitrile oxidoreductase which catalyzes the NADPH-dependent reduction of 7-cyano-7-deazaguanine (preQ0) to 7-aminomethyl-7-deazaguanine, a late step in the biosynthesis of the modified tRNA nucleoside queuosine. Initial crystals of homododecameric Bacillus subtilis QueF diffracted poorly to 8.0 A. A three-dimensional model based on homology with the tunnel-fold enzyme GTP cyclohydrolase I suggested catalysis at intersubunit interfaces and a potential role for substrate binding in quaternary structure stabilization. Guided by this insight, a second crystal form was grown that was strictly dependent on the presence of preQ0. This crystal form diffracted to 2.25 A resolution.
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