TITLE

Heterologous expression of polyhydroxyalkanoate depolymerase from Thermobifida sp. in Pichia pastoris and catalytic analysis by surface plasmon resonance

AUTHOR(S)
Phithakrotchanakoon, Chitwadee; Daduang, Ratama; Thamchaipenet, Arinthip; Wangkam, Thidarat; Srikhirin, Toemsak; Eurwilaichitr, Lily; Champreda, Verawat
PUB. DATE
February 2009
SOURCE
Applied Microbiology & Biotechnology;Feb2009, Vol. 82 Issue 1, p131
SOURCE TYPE
Academic Journal
DOC. TYPE
Article
ABSTRACT
A polyhydroxyalkanote depolymerase gene from Thermobifida sp. isolate BCC23166 was cloned and expressed as a C-terminal His6-tagged fusion in Pichia pastoris. Primary structure analysis revealed that the enzyme PhaZ-Th is a member of a proposed new subgroup of SCL-PHA depolymerase containing a proline–serine repeat linker. PhaZ-Th was expressed as two glycosylated forms with apparent molecular weights of 61 and 70 kDa, respectively. The enzyme showed esterase activity toward p-nitrophenyl alkanotes with V max and K m of 3.63 ± 0.16 μmol min−1 mg−1 and 0.79 ± 0.12 mM, respectively, on p-nitrophenyl butyrate with optimal activity at 50–55°C and pH 7–8. Surface plasmon resonance (SPR) analysis demonstrated that PhaZ-Th catalyzed the degradation of poly-[( R)-3-hydroxybutyrate] (PHB) films, which was accelerated in ( R)-3-hydroxyvalerate copolymers with a maximum degradation rate of 882 ng cm−2 h−1 for poly[( R)-3-hydroxybutyrate-co-3-hydroxyvalerate] (12 mol% V). Surface deterioration, especially on the amorphous regions of PHB films was observed after exposure to PhaZ-Th by atomic force microscopy. The use of P. pastoris as an alternative recombinant system for bioplastic degrading enzymes in secreted form and a sensitive SPR analytical technique will be of utility for further study of bioplastic degradation.
ACCESSION #
36145874

 

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