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Adjustable mutations in lactate (LA)-polymerizing enzyme for the microbial production of LA-based polyesters with tailor-made monomer composition.
- Source :
-
Biomacromolecules [Biomacromolecules] 2010 Mar 08; Vol. 11 (3), pp. 815-9. - Publication Year :
- 2010
-
Abstract
- Lactate (LA)-polymerizing enzyme (LPE) is a newly established class of polyhydroxyalkanoate (PHA) synthase, which can incorporate LA units into a polymer chain. We previously synthesized P(LA-co-3-hydroxybutyrate)s [P(LA-co-3HB)s] in recombinant Escherichia coli using the first LPE, which is the Ser325Thr/Glu481Lys mutant of PHA synthase from Pseudomonas sp. 61-3 [PhaC1(Ps)ST/QK]. In this study, we finely regulated LA fraction in the copolymer by saturated mutations at position 392 (F392X), which corresponds to the activity-enhancing mutations at position 420 of PHA synthase from Ralstonia eutropha. Among the 19 saturated mutants of LPE at position 392, 17 mutants produced P(LA-co-3HB)s with various LA fractions (16-45 mol %), whereas PhaC1(Ps)ST/QK produced P(LA-co-3HB) with 26 mol % LA under the same culture condition. In particular, the F392S mutation exhibited the highest LA fraction of 45 mol %, and also increased polymer content (62 wt %) compared with PhaC1(Ps)ST/QK (44 wt %). Combination of the F392S mutant and anaerobic culture conditions, which promote LA production, led to a further increase in LA fraction up to 62 mol %. The P(LA-co-3HB)s with various LA fractions exhibited altered melting temperatures and melting enthalpy depending on their monomer composition. Accordingly, the mutations at position 392 in LPE greatly contributed to fine-tuning of the LA fraction in the copolymers that is useful for regulating LA fraction-dependent thermal properties.
Details
- Language :
- English
- ISSN :
- 1526-4602
- Volume :
- 11
- Issue :
- 3
- Database :
- MEDLINE
- Journal :
- Biomacromolecules
- Publication Type :
- Academic Journal
- Accession number :
- 20166718
- Full Text :
- https://doi.org/10.1021/bm901437z