Comparative study of the relationship between monomer structure and reactivity for two polyhydroxyalkanoate synthases

• Published in: Applied microbiology and biotechnology Vol. 56; no. 1-2; pp. 131 - 136
• Main Authors: ZHANG, S, KAMACHI, M, TAKAGI, Y, LENZ, R. W, GOODWIN, S
• Format: Journal Article
• Language: English
• Published: Berlin Springer 01.07.2001; Springer Nature B.V
• Subjects: Acyl Coenzyme A - metabolism; Acyltransferases - metabolism; Bacteria; Biological and medical sciences; Biology of microorganisms of confirmed or potential industrial interest; Biotechnology; Carbon; Comparative studies; Ectothiorhodospira shaposhnikovii; Fundamental and applied biological sciences. Psychology; Miscellaneous; Mission oriented research; polyhydroxyalkanoate synthase; Polyhydroxyalkanoates; Polymers; Ralstonia eutropha; Structure-Activity Relationship; Substrate Specificity; Enzyme; Alkanoate(hydroxy) polymer; Synthase; Ectothiorhodospira shaposhnikovii; Rhodospirillales; Ralstonia eutropha; Enzymatic activity; Structure activity relation; Substrate specificity; Bacteria; Ectothiorhodospiraceae; Rhodospirillineae; Comparative study; Alkanoate(hydroxy)polymer
• ISSN: 0175-7598; 1432-0614
• DOI: 10.1007/s002530000562

Using organically synthesized hydroxyalkanoate coenzyme A thioesters, the activities of two short-chain polyhydroxalkanoate (PHA) synthases were investigated--Ralstonia eutropha PHA synthase (a type I PHA synthase) and Ectothiorhodospira shaposhnikovii PHA synthase (a type III synthase). The results indicate that the two synthases have similar activities towards most of the monomers tested. 3-Hydroxybutyryl CoA was found to be the most efficient substrate for both synthases. Changes in the side-chain length of the monomers affect monomer reactivity, with shortening of the side-chain length having the more severe effect. Hydrophobicity in the side chain appears to play an important role in the catalytic reaction. The configuration and the position of the hydroxyl group also affect the reactivity of a monomer. Monomers with the [S] configuration can not be recognized by either synthase. Moving the hydroxyl group from the beta carbon to the alpha carbon has a much more severe effect on the reactivity of the monomer than moving the hydroxyl group to the gamma carbon. The results demonstrate that the in vitro system can be used to prepare entirely novel polymers that may not be obtainable from living cells because of metabolic restrictions.