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  • PublicationJournal Article
    Steroids are found in bacteria and eukaryotes, and genes potentially encoding steroid metabolic enzymes have also been identified in giant viruses. For decades, hydroxylated steroids have been utilized in medicine to treat various human diseases. The hydroxylation of steroids can be achieved using microbial enzymes, especially cytochrome P450 monooxygenases (CYPs/P450s) and is well documented. Understanding the structural determinants that govern the regio- and stereoselectivity of steroid hydroxylation by P450s is essential in order to fully exploit their potential. Herein, we present a comprehensive analysis of the steroid-hydroxylating CYP109 family across the domains of life and delineate the structural determinants that govern steroid hydroxylation. Data mining, annotation, and phylogenetic analysis revealed that CYP109 family members are highly populated in bacteria, and indeed, these members passed from bacteria to archaea by horizontal gene transfer, leading to the evolution of P450s in archaea. Analysis of twelve CYP109 crystal structures revealed large, flexible, and dynamic active site cavities that can accommodate multiple ligands. The correct positioning and orientation of the steroid in the active site cavity and the nature of the C17 substituent on the steroid molecule influence catalysis. In an analogous fashion to the CYP107 family, the amino acid residues within the CYP109 binding pocket involve hydrophilic and hydrophobic interactions, influencing substrate orientations and anchoring and determining the site of hydroxylation and catalytic activity. A handful of amino acids, such as Val84, Val292, and Ser387 in CYP109B4, have been found to play a role in determining the catalytic regiospecificity, and a single amino acid, such as Arg74 in CYP109A2, has been found to be essential for the enzymatic activity. This work serves as a reference for the precise understanding of CYP109 structure–function relationships and for P450 enzymes in general. The findings will guide the genetic engineering of CYP109 enzymes to produce valuable steroid molecules of medicinal and biotechnological importance.
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  • PublicationJournal Article
    Cytochromes P450 are a superfamily of heme-containing monooxygenases involved in a variety of oxidative metabolic reactions, primarily catalyzing the insertion of an oxygen atom into a C-H bond. CYP102 represents the first example of a bacterial P450 that can be classified as a type II (eukaryotic-like) P450 and functions as a catalytically self-sufficient enzyme. These unique features have made CYP102 an attractive system for studying P450 structure and function. However, an overall picture of the specific amino acid residues that are crucial to the functioning of CYP102 and the effect of mutations on the P450 structure and catalysis is yet to be reported. Such an approach will aid protein engineering approaches used to improve this enzyme. To address this research knowledge gap, we have investigated 105 CYP102 crystal structures in this study. We demonstrate that the CYP102 active site is highly dynamic and flexible. Amino acid residues that play critical roles in substrate binding, orientation, and anchoring were identified. Mutational studies highlighted the roles of amino acids and provided possible bioengineering improvement strategies for CYP102. Decoy molecules are a promising agent for deceiving CYP102 and permitting non-native substrates into the active site. Ru(II)-diimine photosensitizers and zinc/cobalt (III) sepulchrate (Co(III)Sep) could be used as alternative electron sources. The present study serves as a reference for understanding the structure–functional analysis of CYP102 family members precisely and of P450 enzymes in general. Significantly, this work contributes to the effort to develop an improved CYP102 enzyme, thereby advancing the field of P450 research and potentially leading to new industrial applications.
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  • PublicationJournal Article
    Cytochrome P450 monooxygenases (CYPs; P450s) are a superfamily of heme-containing enzymes that are recognized for their vast substrate range and oxidative multifunctionality. CYP107 family members perform hydroxylation and epoxidation processes, producing a variety of biotechnologically useful secondary metabolites. Despite their biotechnological importance, a thorough examination of CYP107 protein structures regarding active site cavity dynamics and key amino acids interacting with bound ligands has yet to be undertaken. To address this research knowledge gap, 44 CYP107 crystal structures were investigated in this study. We demonstrate that the CYP107 active site cavity is very flexible, with ligand binding reducing the volume of the active site in some situations and increasing volume size in other instances. Polar interactions between the substrate and active site residues result in crucial salt bridges and the formation of proton shuttling pathways. Hydrophobic interactions, however, anchor the substrate within the active site. The amino acid residues within the binding pocket influence substrate orientation and anchoring, determining the position of the hydroxylation site and hence direct CYP107’s catalytic activity. Additionally, the amino acid dynamics within and around the binding pocket determine CYP107’s multifunctionality. This study serves as a reference for understanding the structure–function analysis of CYP107 family members precisely and the structure–function analysis of P450 enzymes in general. Finally, this work will aid in the genetic engineering of CYP107 enzymes to produce novel molecules of biotechnological interest.
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