Open AccessProperties of a Novel Intracellular Poly(3-Hydroxybutyrate) Depolymerase with High Specific Activity (PhaZd) in Wautersia eutropha H16
Author(s) -
Tomoko Abe,
T Kobayashi,
Terumi Saito
Publication year - 2005
Publication title -
journal of bacteriology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.652
H-Index - 246
eISSN - 1067-8832
pISSN - 0021-9193
DOI - 10.1128/jb.187.20.6982-6990.2005
Subject(s) - ralstonia , biochemistry , biology , intracellular , cupriavidus necator , polyhydroxybutyrate , extracellular , mutant , cytosol , enzyme , oxyanion , microbiology and biotechnology , bacteria , polyhydroxyalkanoates , gene , genetics , catalysis
A novel intracellular poly(3-hydroxybutyrate) (PHB) depolymerase (PhaZd) ofWautersia eutropha (formerlyRalstonia eutropha ) H16 which shows similarity with the catalytic domain of the extracellular PHB depolymerase inRalstonia pickettii T1 was identified. The positions of the catalytic triad (Ser190 -Asp266 -His330 ) and oxyanion hole (His108 ) in the amino acid sequence of PhaZd deduced from the nucleotide sequence roughly accorded with those of the extracellular PHB depolymerase ofR. pickettii T1, but a signal peptide, a linker domain, and a substrate binding domain were missing. The PhaZd gene was cloned and the gene product was purified fromEscherichia coli . The specific activity of PhaZd toward artificial amorphous PHB granules was significantly greater than that of other known intracellular PHB depolymerase or 3-hydroxybutyrate (3HB) oligomer hydrolases ofW. eutropha H16. The enzyme degraded artificial amorphous PHB granules and mainly released various 3-hydroxybutyrate oligomers. PhaZd distributed nearly equally between PHB inclusion bodies and the cytosolic fraction. The amount of PHB was greater inphaZd deletion mutant cells than the wild-type cells under various culture conditions. These results indicate that PhaZd is a novel intracellular PHB depolymerase which participates in the mobilization of PHB inW. eutropha H16 along with other PHB depolymerases.