Phloroglucinol synthase

Phloroglucinol synthase is an acetyltransferase enzyme involved in the synthesis of phloroglucinol (also known as 1,3,5-trihydroxybenzene or cyclohexane-1,3,5-trione), a pharmaceutically and industrially important benzentriol molecule used in medicines and explosives. The enzyme, as taken from the bacterium pseudomonas protegens (Pf-5), is a type III polyketide synthase. The enzyme cyclizes the activated form of 3,5-dioxoheptanedioate. Phloroglucinol synthase exhibits broad substrate specificity, able to accept C4-C12 aliphatic acyl-CoAs and phenylacetyl-CoAs, yielding polyoxoalkylated alpha-pyrones by condensation with malonyl-CoA.^[1] The enzyme catalyzes the following reaction,

3 malonyl-CoA + 3 H⁺ = Phloroglucinol + 3 CO₂ + 3 CoA

Phloroglucinol synthase
The enzyme as folded by AlphaFold
Identifiers
EC no.	2.3.1.253
Databases
IntEnz	IntEnz view
BRENDA	BRENDA entry
ExPASy	NiceZyme view
KEGG	KEGG entry
MetaCyc	metabolic pathway
PRIAM	profile
PDB structures	RCSB PDB PDBe PDBsum
Search PMC articles PubMed articles NCBI proteins

It was shown that the k_cat for this enzyme (with malony-CoA as a substrate) was 10 min^-1. Its product, phloroglucinol is used in industry as well as in the synthesis of pharmaceuticals. It can be used to make phloroglucinol but it shows low productivity.^[2][3]