Document Detail


Precise control of repeating unit composition in biodegradable poly(3-hydroxyalkanoate) polymers synthesized by Escherichia coli.
MedLine Citation:
PMID:  22248859     Owner:  NLM     Status:  Publisher    
Abstract/OtherAbstract:
The composition of medium-chain-length (MCL) poly(3-hydroxyalkanoate) (PHA) biopolymers is normally an uncontrollable random mixture of repeating units with differing side chain lengths. Attempts to generate MCL PHA homopolymers and control repeating unit composition have been published in native PHA-producing organisms but have limited ranges for the different sizes of repeating units that can be synthesized. In this study, a new Escherichia coli-based system that exhibits control over repeating unit composition for both MCL PHAs and short-chain-length (SCL) PHAs has been developed, covering an unprecedented range of repeating units. The fadB and fadJ genes from the β-oxidation pathway were eliminated from the chromosome of E. coli LS5218. The subsequent blockage in β-oxidation caused a buildup of enoyl-CoA intermediates, which were converted to PHAs by an (R)-specific enoyl-CoA hydratase (PhaJ4) and PHA synthase [PhaC1(STQK)] expressed from a plasmid DNA construct. Fatty acid substrates were converted to PHAs with repeating units equal in the number of carbon atoms to the fatty acid substrate. The broad substrate specificities of the PhaJ4 and PhaC1(STQK) enzymes allowed for the production of homopolymers with strict control over the repeating unit composition from substrates of four to twelve carbons in length. Polymers were purified and analyzed by GC, GC-MS, and NMR for structural composition and by DSC, TGA, and GPC for thermal and physical characteristics. This study marks the development of the first single biological system to achieve consistent repeating unit control over such a broad range of repeating units in PHAs.
Authors:
Ryan C Tappel; Qin Wang; Christopher T Nomura
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Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2012-1-14
Journal Detail:
Title:  Journal of bioscience and bioengineering     Volume:  -     ISSN:  1347-4421     ISO Abbreviation:  -     Publication Date:  2012 Jan 
Date Detail:
Created Date:  2012-1-17     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  100888800     Medline TA:  J Biosci Bioeng     Country:  -    
Other Details:
Languages:  ENG     Pagination:  -     Citation Subset:  -    
Copyright Information:
Copyright © 2011 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.
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