The structure of PhaZ7 at atomic (1.2 A) resolution reveals details of the active site and suggests a substrate-binding mode.

摘要: Poly-(R)-hydroxyalkanoates (PHAs) are bacterial polyesters that degraded by a group of enzymes known as PHA depolymerases. Paucimonas lemoignei PhaZ7 depolymerase is the only extracellular has been described being active towards amorphous PHAs. A previously determined crystal structure revealed an alpha/beta-hydrolase fold and Ser-His-Asp catalytic triad. In order to address questions regarding mechanism substrate binding, atomic resolution was after cocrystallization with protease inhibitor PMSF. The reported highest (1.2 A) currently structures shows sulfur dioxide molecule covalently attached active-site residue Ser136. Structural comparison free (1.45 resolution) no major changes in site, suggesting preformed oxyanion hole found be formed amide groups Met137 Asn49. Nine well ordered water molecules were located site. Manual docking trimer showed positions these coincide atoms. It proposed displaced upon binding substrate. Furthermore, conformational identified dimer different space group. surface loops involved formation, indicating some flexibility their possible involvement polyester binding.