Seminars

 Polyhydroxyalkanoates (PHAs) are biodegradable polyesters synthesized by microorganisms as intracellular carbon and energy storage materials. They have garnered attention as a sustainable alternative to petrochemical plastics because they
can be produced from renewable plant oils, are biodegradable, and possessed mechanical properties comparable to commodity plastics. However, the lack of structural and mechanistic insights into the key enzyme in PHA biosynthesis, PHA
synthase (PhaC), has significantly limited the industrial development.
 Through structural and biochemical approaches, we determined the full-length crystal structures of Aeromonas caviae PhaC, an industrially relevant enzyme [1]. Previously, our group also determined the structures of the free and CoA-bound forms of the C-terminal domain of Chromobacterium sp. USM2 PhaC [2,3]. Altogether, these structures reveal three critical regions in PHA polymerization: substrate entry, catalytic pocket, and product egress.
 Although the full-length PhaC structure represents a major advance toward rational enzyme engineering for bioplastic production, the catalytic mechanism underlying this unique non-template polymerization process remains unclear. Continued structural and functional investigations are  essential to advance both fundamental understanding and translational application in sustainable bioplastic production.