STRUCTURE OF NITRILE REDUCTASE

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This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. QueF is a nitrile oxidoreductase which catalyzes a late step in the biosynthesis of the modified tRNA nucleoside queuosine. The presence of queuosine in the anticodons of these tRNAs (including mitochondrial tRNAs) is compatible with a fundamental role in translation, specifically in modulating fidelity. Disruption of queosine biosynthesis in the pathogenic bacterium Shigella flexneri results in loss of pathogenicity, making several enzymes in its biosynthesis pathway attractive targets for anti-shigellosis drugs. The structure solution of nitrile reductase has been attempted by molecular replacement using an informatics generated model based on a related structure, and MAD using crystals soaked in TaBr derivative. That MAD data were collected on beamline BL9-2. Molecular replacement has been unsuccessful. The MAD phases have resulted in a partial model to low resolution (4 A). Refinement of this model is in progress.