Diverse enzymatic chemistry for propionate side chain cleavages in tetrapyrrole biosynthesis

Abstract

Tetrapyrroles represent a unique class of natural products that possess diverse chemical architectures and exhibit a broad range of biological functions. Accordingly, they attract keen attention from the natural product community. Many metal-chelating tetrapyrroles serve as enzyme cofactors essential for life, while certain organisms produce metal-free porphyrin metabolites with biological activities potentially beneficial for the producing organisms and for human use. The unique properties of tetrapyrrole natural products derive from their extensively modified and highly conjugated macrocyclic core structures. Most of these various tetrapyrrole natural products biosynthetically originate from a branching point precursor, uroporphyrinogen III, which contains propionate and acetate side chains on its macrocycle. Over the past few decades, many modification enzymes with unique catalytic activities, and the diverse enzymatic chemistries employed to cleave the propionate side chains from the macrocycles, have been identified. In this review, we highlight the tetrapyrrole biosynthetic enzymes required for the propionate side chain removal processes and discuss their various chemical mechanisms.

Unusual Enzymatic C–C Bond Formation and Cleavage Reactions during Natural Product Biosynthesis

“…However, these biosynthetic pathways remain unexplored, and further studies are necessary to test these hypotheses. 59)…”

Tolyporphins–Exotic Tetrapyrrole Pigments in a Cyanobacterium—A Review

“…Understanding how hydrocarbon (vinyl) groups are removed from the β-pyrrolic positions downstream from uroporphyrinogen III, presumably by the TolI enzyme, is of utmost interest. Research on this topic is under active investigation [ 217 ]. One pathway entails formation of tetravinylporphyrinogen P, followed by hydration and loss of acetaldehyde from each position, thereby forming tolyporphyrinogen P. The role of tolyporphyrinogen P as a possible intermediate for late-stage diversification to form the entire repertoire of tolyporphins is a recent and intriguing hypothesis.…”