dTDP

dTDP, short for deoxythymidine diphosphate, is a nucleotide consisting of a deoxyribose sugar attached to the thymine base and two phosphate groups. It is part of the cellular deoxyribonucleotide pool and functions as an activated precursor in nucleotide metabolism, acting as an intermediate toward the formation of dTTP for DNA synthesis.

In cellular metabolism, dTMP is phosphorylated to dTDP by thymidylate kinase. dTDP can then be phosphorylated to the triphosphate form dTTP by nucleoside diphosphate kinases (NDK) or related kinases. The balance of dNDPs and dNTPs is tightly regulated because imbalances can impact DNA replication fidelity and cell viability.

Beyond its role in DNA precursor synthesis, the dTDP moiety serves as a donor in the biosynthesis of activated sugars. dTDP-glucose and related dTDP-sugars function as sugar donors in glycosylation reactions that generate diverse polysaccharides and glycoconjugates. In bacteria, dTDP-sugars are essential for producing components such as dTDP-rhamnose, which contribute to cell wall and surface structures.

dTDP is present across domains of life, including bacteria, archaea, and eukaryotes, where it participates in both nucleotide metabolism and specialized biosynthetic pathways. Its levels are coordinated with other deoxynucleotides to support DNA replication and broader cellular carbohydrate biosynthesis.