Biosynthesis of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) containing a predominant amount of 3-hydroxyvalerate by engineered Escherichia coli expressing propionate-CoA transferase.
OBJECTIVE
Of the biodegradable polyhydroxyalkanoates (PHAs), poly(hydroxybutyrate-co-hydroxyvalerate) (P(HB-co-HV)) is often considered for fabrication of biocompatible and absorbable medical devices and other applications. Depending on the application, however, specific mechanical or processing properties must be improved. To address these required properties, we sought to alter the monomer composition of the copolymer by a combination genetic engineering in an Escherichia coli host and carbon substrate feeding.


RESULTS
We applied a new method of 3-hydroxyvalerate (3HV) monomer synthesis to produce a co-polymer by the introduction of a propionyl-CoA transferase gene (pct), along with PHA biosynthetic genes bktB, phaB and phaC from Ralstonia eutropha into engineered E. coli to produce P(HB-co-HV). The resulting strain successfully produced the copolymer containing an ultra-high 3HV monomer composition (over 80 wt%).


CONCLUSIONS
To the best of our knowledge, the P(HB-co-HV) production strain constructed here synthesized polymer with the highest 3HV content of any engineered E. coli strain. This strain could also produce P(HB-co-HV) with the use of lower concentrations of propionate in the growth medium, compared to other reported strains, which could avoid the known growth inhibition from propionate in E. coli.


CONCLUSIONS
Polyhydroxyalkanoates have been emphasized as a potential alternative for petroleum-based plastics by virtue of their physical properties and environmentally friendly characteristics. The copolymer produced in this work validates our genetic engineering approach and suggests that the Pct enzyme is a more efficient method for production of propionyl-CoA, the 3-hydroxyvaleryl-CoA precursor.
Department of Microbial Engineering, College of Engineering, Konkuk University, Seoul, South Korea.
Y-H
YH
Yang
C J
CJ
Brigham
E
E
Song
J-M
JM
Jeon
C K
CK
Rha
A J
AJ
Sinskey
D015256:Coenzyme A-Transferases / Q000235:genetics / Q000378:metabolism*; D020118:Cupriavidus necator / Q000201:enzymology / Q000235:genetics; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism*; D005818:Genetic Engineering; D007218:Industrial Microbiology; D010421:Pentanoic Acids / Q000378:metabolism*; D011091:Polyesters / Q000378:metabolism*; D011422:Propionates / Q000378:metabolism; D000094122:Polyhydroxybutyrates
D015256:Coenzyme A-Transferases; D010421:Pentanoic Acids; D011091:Polyesters; D011422:Propionates; C052620:poly(3-hydroxybutyrate)-co-(3-hydroxyvalerate); D000094122:Polyhydroxybutyrates; C013056:beta-hydroxyvaleric acid; C031212:acyl-CoA transferase