9BYU

Structure and stability of an apo thermophilic esterase that hydrolyzes polyhydroxybutyrate

Summary for 9BYU

• Entry DOI: 10.2210/pdb9byu/pdb
• Descriptor: Esterase, PHB depolymerase family, 2-AMINO-2-HYDROXYMETHYL-PROPANE-1,3-DIOL, MAGNESIUM ION, ... (4 entities in total)
• Functional Keywords: bioplastic, enzymology, polyhydroxyalkanoates, polymer hydrolysis, thermophile, polyhydroxybutyrate depolymerase, biosynthetic protein
• Biological source: Lihuaxuella thermophila
• Total number of polymer chains: 1
• Total formula weight: 32588.32

Authors

Thomas, G.M.,Quirk, S.,Huard, D.J.E.,Lieberman, R.L. (deposition date: 2024-05-24, release date: 2024-11-06, Last modification date: 2024-11-27)

Primary citation

Thomas, G.M.,Quirk, S.,Lieberman, R.L.
Structure and stability of an apo thermophilic esterase that hydrolyzes polyhydroxybutyrate.
Acta Crystallogr D Struct Biol, 80:791-799, 2024

PubMed Abstract: Pollution from plastics is a global problem that threatens the biosphere for a host of reasons, including the time scale that it takes for most plastics to degrade. Biodegradation is an ideal solution for remediating bioplastic waste as it does not require the high temperatures necessary for thermal degradation and does not introduce additional pollutants into the environment. Numerous organisms can scavenge for bioplastics, such as polylactic acid (PLA) or poly-(R)-hydroxybutyrate (PHB), which they can use as an energy source. Recently, a promiscuous PHBase from the thermophilic soil bacterium Lihuaxuella thermophila (LtPHBase) was identified. LtPHBase can accommodate many substrates, including PHB granules and films and PHB block copolymers, as well as the unrelated polymers polylactic acid (PLA) and polycaprolactone (PCL). LtPHBase uses the expected Ser-His-Asp catalytic triad for hydrolysis at an optimal enzyme activity near 70°C. Here, the 1.75 Å resolution crystal structure of apo LtPHBase is presented and its chemical stability is profiled. Knowledge of its substrate preferences was extended to different-sized PHB granules. It is shown that LtPHBase is highly resistant to unfolding, with barriers typical for thermophilic enzymes, and shows a preference for low-molecular-mass PHB granules. These insights have implications for the long-term potential of LtPHBase as an industrial PHB hydrolase and shed light on the evolutionary role that this enzyme plays in bacterial metabolism.

PubMed: 39441250
DOI: 10.1107/S2059798324009707

Experimental method

X-RAY DIFFRACTION (1.75 Å)