IPTentsyymit

IPTentsyymit, or isopentenyltransferases, are a family of enzymes that catalyze the transfer of an isopentenyl group to adenine-containing substrates. The family is found in plants, bacteria and archaea, and it supports two main functional roles: cytokinin biosynthesis and tRNA modification.

In plants, IPTentsyymit initiate cytokinin biosynthesis by transferring the isopentenyl moiety from dimethylallyl diphosphate to adenosine phosphate substrates, forming isopentenyladenosine-containing nucleotides. These compounds are precursors to active cytokinins, which regulate cell division, shoot and root development, leaf senescence, and meristem activity. Plant IPT genes are typically part of a multigene family and show tissue-specific and developmentally regulated expression. IPT activity is integrated with other cytokinin metabolic pathways to maintain hormone homeostasis.

A second mode of IPT action occurs in tRNA modification, where IPTs prenylate adenine at position 37 (i6A37) in certain tRNAs. This modification supports proper codon-anticodon pairing and translational fidelity, contributing to efficient protein synthesis.

Biological significance and regulation: Through cytokinin production, IPTentsyymit influence plant architecture, timing of flowering, senescence, and nutrient responses. Their expression and activity respond to nutrient status, light, sugars, and stress, enabling adaptive growth. In bacteria and some archaea, IPTs contribute to tRNA modification or to cytokinin-like molecules, reflecting an evolutionarily conserved mechanism of prenyl transfer.

Overall, IPTentsyymit are conserved prenyltransferases with central roles in cellular regulation via cytokinin pathways and tRNA biology.