<p>The reaction catalysed by this enzyme (designated QueE) is unknown, but it is necessary for the biosynthesis, from GTP, of 7-cyano-7-deazaguanosine, also called preQ0 because in many species it is a precursor of the tRNA modified base queuosine [<cite idref="PUB00035932"/>]. In most archaeal species 7-cyano-7-deazaguanosine is instead the precursor of a different tRNA modified base, archaeosine.</p> 7-cyano-7-deazaguanosine (preQ0) biosynthesis protein QueE