MurAMurF

MurAMurF is a proposed or observed bifunctional enzyme that combines the catalytic domains of MurA and MurF into a single polypeptide. In annotated genomes and some laboratory constructs, MurAMurF is described as a fusion protein linking the initial and final cytoplasmic steps of peptidoglycan precursor synthesis, potentially enabling substrate channeling between the two reactions.

In bacteria, MurA and MurF are normally encoded by separate genes, murA and murF, and participate in sequential steps of the cytoplasmic phase of peptidoglycan biosynthesis. MurA catalyzes the first committed step, transferring the enolpyruvyl moiety from phosphoenolpyruvate to UDP-N-acetylglucosamine. MurF catalyzes the ligation of the UDP-N-acetylmuramoyl-tripeptide with the dipeptide D-Ala-D-Ala to form UDP-N-acetylmuramoyl-pentapeptide, a precursor that proceeds to membrane-associated stages of cell wall assembly.

The exact distribution and significance of MurAMurF are not fully established. Reported instances suggest either rare natural occurrence in a few bacterial genomes or engineered fusion constructs designed to study enzyme cooperation and substrate channeling. The typical domain organization would comprise an N-terminal MurA-like domain linked to a C-terminal MurF-like domain, with a flexible linker in between. Structural and biochemical investigations aim to determine whether such fusions enhance catalytic efficiency, alter regulatory control, or affect sensitivity to antibiotics targeting MurA or related steps.

MurAMurF remains a niche topic within bacterial cell wall biosynthesis, primarily of interest for understanding domain cooperation in multienzyme pathways and for exploring novel targets in antibacterial research. See also MurA and MurF for related enzymology and pathway context.