Abstract
The multicopper oxidase phenoxazinone synthase (PHS) catalyzes the penultimate step in the biosynthesis of the antibiotic actinomycin D by Streptomyces antibioticus. PHS exists in two oligomeric forms: a dimeric form and a hexameric form, with older actinomycin-producing cultures containing predominately the hexameric form. The structure of hexameric PHS has been determined using X-ray diffraction to a resolution limit of 2.30 Å and is found to contain several unexpected and distinctive features. The structure forms a hexameric ring that is centered on a pseudo 6-fold axis and has an outer diameter of 185 Å with a large central cavity that has a diameter of 50 Å. This hexameric structure is stabilized by a long loop connecting two domains; bound to this long loop is a fifth copper atom that is present as a type 2 copper. This copper atom is not present in any other multicopper oxidase, and its presence appears to stabilize the hexameric structure.
Original language | English (US) |
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Pages (from-to) | 4378-4387 |
Number of pages | 10 |
Journal | Biochemistry |
Volume | 45 |
Issue number | 14 |
DOIs | |
State | Published - Apr 11 2006 |
ASJC Scopus subject areas
- Biochemistry