ThyX
ThyX, formally known as flavin-dependent thymidylate synthase (FDTS), is an alternative thymidylate synthase found in a broad set of bacteria and archaea. Unlike the classical thymidylate synthase ThyA, ThyX catalyzes the conversion of deoxyuridylate (dUMP) to deoxythymidylate (dTMP) using methylenetetrahydrofolate as a one-carbon donor and flavin adenine dinucleotide (FAD) as a cofactor. The enzyme’s mechanism and cofactor dependencies distinguish it from ThyA and reflect its distinct evolutionary origin.
Distribution and significance: ThyX is present in organisms that lack ThyA or that rely on the pathway
Structure and mechanism: ThyX proteins typically function as oligomers (often dimers) and form an active site
History and nomenclature: The family was identified in the late 1990s to early 2000s and named ThyX