Title : Structural insight into the poly(3-hydroxybutyrate) hydrolysis by intracellular PHB depolymerase from Bacillus thuringiensis - Wang_2024_Int.J.Biol.Macromol__137999 |
Author(s) : Wang YL , Ye LC , Chang SC , Chen SC , Hsu CH |
Ref : Int J Biol Macromol , :137999 , 2024 |
Abstract :
Poly((R)-3-hydroxybutyrate) (PHB) is a microbial biopolymer widely used in commercial biodegradable plastics. PHB degradation in cell is catalyzed by PHB depolymerase (PhaZ), which hydrolyzes the polyester into mono- and/or oligomeric (R)-3-hydroxylbutyrates (3HB). A novel intracellular PhaZ from Bacillus thuringiensis (BtPhaZ) was identified for potential applications in polymer biodegradation and 3HB production. Herein, we present the crystal structure of BtPhaZ at 1.42-A resolution, making the first crystal structure for an intracellular PhaZ. BtPhaZ comprises a canonical alpha/beta hydrolase catalytic domain and a unique alpha-helical cap domain. Despite lacking sequence similarity, BtPhaZ shares high structural homology with many alpha/beta hydrolase members, exhibiting a similar active-site architecture. Alongside the most conserved superfamily signature, several new conserved signatures have been identified, contributing not only to the formations of the Ser-His-Asp catalytic triad and the oxyanion hole but also to the active-site conformation. The putative P-1 subsite appears to have limited space for accommodating only one 3HB-monomer, which may provide an explanation why the major hydrolytic product for BtPhaZ is monomeric form. Furthermore, a cluster of solvent-exposed hydrophobic residues in the helical cap domain forms an adsorption site for polymer-binding. Detailed structural comparisons reveal that various PhaZs employ distinct residues for the biopolymer-binding and hydrolysis. |
PubMedSearch : Wang_2024_Int.J.Biol.Macromol__137999 |
PubMedID: 39592048 |
Gene_locus related to this paper: bacce-BC3312 |
Gene_locus | bacce-BC3312 |
Structure | 8YNV 8YNW |
Wang YL, Ye LC, Chang SC, Chen SC, Hsu CH (2024)
Structural insight into the poly(3-hydroxybutyrate) hydrolysis by intracellular PHB depolymerase from Bacillus thuringiensis
Int J Biol Macromol
:137999
Wang YL, Ye LC, Chang SC, Chen SC, Hsu CH (2024)
Int J Biol Macromol
:137999