Aromatic prenyltransferase Orf2
Streptomyces sp. strain CL190 (bacteria)
Isoprenoid is the most abundant natural product (natural organic compound) in nature. Basically, it is biosynthesized and is composed of multiple isoprene unit containing five carbons. There are several isoprenoid chains: the dimethylallyl chain composed of five carbons, the geranyl chain composed of ten carbons and the farnesyl chain composed of fifteen carbons. On the other hand, polyketide is a derivative of a beta-ketomethylene chain, formed by decarboxylation of malony CoA that is made from acetyl CoA. One of the hybrid type natural products, which is called naphterpine, is composed of polyketide and one of the isoprenoids, a geranyl group. The hybrid type organic natural product like this gets its bioactivity when it contains an added isoprenyl group. Some of these become new anti-microbial, anti-oxidant, anti-inflammatory, anti-viral, and anti-cancer compounds.
Aromatic prenyltransferase (PTase) is an enzyme catalyzing the prenyl group attachment reaction which adds an isoprenyl group to other compounds, but there are few PTases which have been purified and identified. The structure shown here is a complex of PTase from the mycobacterium, Streptomyces sp. CL 190 with its substrate. PTase is composed of a new type of barrel, PTbarrel. There are ten anti parallel beta strands making a cylinder shape around the center core that is filled by substrate or solvent, and at the outside of this, there are ring shaped alpha helices exposed to the external solvent. The center core space where the substrates will be bound is relatively large. This evidence could explain why this enzyme can accept relatively wide range of aromatic small molecules as substrates.
Protein Data Bank (PDB)
author: Sachiyo Nomura