Structural Insights into Azole-based Inhibitors of Heme Oxygenase-1: Development of Selective Compounds for Therapeutic Applications

2019 ◽  
Vol 25 (42) ◽  
pp. 5803-5821 ◽  
Author(s):  
Mona N. Rahman ◽  
Dragic Vukomanovic ◽  
Jason Z. Vlahakis ◽  
Walter A. Szarek ◽  
Kanji Nakatsu ◽  
...  
Keyword(s):  
Heme Oxygenase ◽  
Competitive Inhibition ◽  
Cytochromes P450 ◽  
Structural Similarity ◽  
Binding Pocket ◽  
Initial Study ◽  
Structural Basis ◽  
Heme Oxygenase 1 ◽  
Design Strategies ◽  
Inhibitor Binding

The development of isozyme-selective heme oxygenase (HO) inhibitors promises powerful pharmacological tools to elucidate the regulatory characteristics of the HO system. It is already known that HO has cytoprotective properties with a role in several disease states; thus, it is an enticing therapeutic target. Historically, the metalloporphyrins have been used as competitive HO inhibitors based on their structural similarity to the substrate, heme. However, heme’s important role in several other proteins (e.g. cytochromes P450, nitric oxide synthase), results in non-selectivity being an unfortunate side effect. Reports that azalanstat and other non-porphyrin molecules inhibited HO led to a multi-faceted effort over a decade ago to develop novel compounds as potent, selective inhibitors of HO. The result was the creation of the first generation of non-porphyrin based, non-competitive inhibitors with selectivity for HO, including a subset with isozyme selectivity for HO-1. Using X-ray crystallography, the structures of several complexes of HO-1 with novel inhibitors have been elucidated and provided insightful information regarding the salient features required for inhibitor binding. This included the structural basis for non-competitive inhibition, flexibility and adaptability of the inhibitor binding pocket, and multiple, potential interaction subsites, all of which can be exploited in future drug-design strategies. Notably, HO-1 inhibitors are of particular interest for the treatment of hyperbilirubinemia and certain types of cancer. Key features based on this initial study have already been used by others to discover additional potential HO-1 inhibitors. Moreover, studies have begun to use selected compounds and determine their effects in some disease models.

scholarly journals Structural insights into human heme oxygenase-1 inhibition by potent and selective azole-based compounds

2013 ◽  
Vol 10 (78) ◽  
pp. 20120697 ◽  
Author(s):  
Mona N. Rahman ◽  
Dragic Vukomanovic ◽  
Jason Z. Vlahakis ◽  
Walter A. Szarek ◽  
Kanji Nakatsu ◽  
...  
Keyword(s):  
Heme Oxygenase ◽  
Competitive Inhibition ◽  
Cytochromes P450 ◽  
Structural Similarity ◽  
Binding Pocket ◽  
Potential Interaction ◽  
Structural Basis ◽  
Heme Oxygenase 1 ◽  
Design Strategies ◽  
Inhibitor Binding

The development of heme oxygenase (HO) inhibitors, especially those that are isozyme-selective, promises powerful pharmacological tools to elucidate the regulatory characteristics of the HO system. It is already known that HO has cytoprotective properties and may play a role in several disease states, making it an enticing therapeutic target. Traditionally, the metalloporphyrins have been used as competitive HO inhibitors owing to their structural similarity with the substrate, heme. However, given heme's important role in several other proteins (e.g. cytochromes P450, nitric oxide synthase), non-selectivity is an unfortunate side-effect. Reports that azalanstat and other non-porphyrin molecules inhibited HO led to a multi-faceted effort to develop novel compounds as potent, selective inhibitors of HO. This resulted in the creation of non-competitive inhibitors with selectivity for HO, including a subset with isozyme selectivity for HO-1. Using X-ray crystallography, the structures of several complexes of HO-1 with novel inhibitors have been elucidated, which provided insightful information regarding the salient features required for inhibitor binding. This included the structural basis for non-competitive inhibition, flexibility and adaptability of the inhibitor binding pocket, and multiple, potential interaction subsites, all of which can be exploited in future drug-design strategies.

scholarly journals Structural insights into heme oxygenase-1 inhibition by azole-based compounds

2014 ◽  
Vol 70 (a1) ◽  
pp. C831-C831
Author(s):  
Mona Rahman ◽  
Dragic Vukomanovic ◽  
Jason Vlahakis ◽  
Walter Szarek ◽  
Kanji Nakatsu ◽  
...  
Keyword(s):  
Heme Oxygenase ◽  
Competitive Inhibition ◽  
Cytochromes P450 ◽  
Binding Pocket ◽  
Heme Iron ◽  
Structural Basis ◽  
Heme Oxygenase 1 ◽  
Design Strategies ◽  
Selective Inhibitors ◽  
Inhibitor Binding

The development of heme oxygenase (HO) inhibitors, especially those that are isozyme-selective, promises powerful pharmacological tools to elucidate the regulatory characteristics of the HO system. HO is known to have cytoprotective properties with a role in several disease states; thus, it is an enticing therapeutic target. Traditionally, given their structural similarity with heme, the metalloporphyrins have been used as competitive HO inhibitors. However, given heme's important role in several other proteins (e.g. cytochromes P450, nitric oxide synthase), nonselectivity is an unfortunate side-effect. Reports that azalanstat and other non-porphyrin molecules inhibited HO led to a multi-faceted effort to develop novel compounds as potent, selective inhibitors of HO. This resulted in the creation of non-competitive HO-selective inhibitors, including a subset with isozyme selectivity for HO-1. Using X-ray crystallography, the structures of several complexes of HO-1 with novel inhibitors have been elucidated, providing insightful information regarding the salient features required for inhibitor binding. This included the structural basis for non-competitive inhibition, flexibility and adaptability of the inhibitor binding pocket, and multiple, potential interaction subsites, all of which can be exploited in future drug-design strategies. The structures revealed a common binding mode, despite different structural fragments, with the flexibility to accommodate bulkier substituents via "induced fit". Compounds bind to the distal side of heme through an azole ``anchor" which coordinates with the heme iron. Expansion of the distal pocket, mainly due to distal helix flexibility, allows accommodation of the compounds, with a distal hydrophobic pocket providing further stabilization yet without displacing heme or the critical Asp140 residue. Rather, binding displaces a catalytically critical water molecule and disrupts an ordered hydrogen-bond network involving Asp140.

scholarly journals Perspective on the Structural Basis for Human Aldo-Keto Reductase 1B10 Inhibition

Metabolites ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 865
Author(s):  
Francesc Xavier Ruiz ◽  
Xavier Parés ◽  
Jaume Farrés
Keyword(s):  
Enzyme Inhibitors ◽  
Binding Pocket ◽  
Anion Binding ◽  
Structural Basis ◽  
Inhibitor Binding ◽  
Reversible Inhibitors ◽  
Alternative Conformation ◽  
Variable Loops ◽  
Cancer Types

Human aldo-keto reductase 1B10 (AKR1B10) is overexpressed in many cancer types and is involved in chemoresistance. This makes AKR1B10 to be an interesting drug target and thus many enzyme inhibitors have been investigated. High-resolution crystallographic structures of AKR1B10 with various reversible inhibitors were deeply analyzed and compared to those of analogous complexes with aldose reductase (AR). In both enzymes, the active site included an anion-binding pocket and, in some cases, inhibitor binding caused the opening of a transient specificity pocket. Different structural conformers were revealed upon inhibitor binding, emphasizing the importance of the highly variable loops, which participate in the transient opening of additional binding subpockets. Two key differences between AKR1B10 and AR were observed regarding the role of external loops in inhibitor binding. The first corresponded to the alternative conformation of Trp112 (Trp111 in AR). The second difference dealt with loop A mobility, which defined a larger and more loosely packed subpocket in AKR1B10. From this analysis, the general features that a selective AKR1B10 inhibitor should comply with are the following: an anchoring moiety to the anion-binding pocket, keeping Trp112 in its native conformation (AKR1B10-like), and not opening the specificity pocket in AR.

scholarly journals Heme oxygenase-1 affects cytochrome P450 function through the formation of heteromeric complexes: Interactions between CYP1A2 and heme oxygenase-1

2020 ◽  
pp. jbc.RA120.015911
Author(s):  
J. Patrick Connick ◽  
James R. Reed ◽  
George F. Cawley ◽  
Wayne L. Backes
Keyword(s):  
Cytochrome P450 ◽  
Heme Oxygenase ◽  
Cytochromes P450 ◽  
Resonance Energy Transfer ◽  
Resonance Energy ◽  
Stable Complex ◽  
Heme Oxygenase 1 ◽  
Cytochrome P450 Reductase ◽  
Xenobiotic Exposure ◽  
Substantial Inhibition

Heme oxygenase 1 (HO‑1) and the cytochromes P450 (P450s) are endoplasmic reticulum-bound enzymes that rely on the same protein, NADPH-cytochrome P450 reductase (POR), to provide the electrons necessary for substrate metabolism.  Although the HO‑1 and P450 systems are interconnected due to their common electron donor, they generally have been studied separately.  As the expression of both HO-1 and P450s are affected by xenobiotic exposure, changes in HO‑1 expression can potentially affect P450 function, and conversely, changes in P450 expression can influence HO‑1.  The goal of this study was to examine interactions between the P450 and HO‑1 systems.  Using bioluminescence resonance energy transfer (BRET), HO‑1 formed HO‑1•P450 complexes with CYP1A2, CYP1A1, and CYP2D6, but not all P450s.  Studies then focused on the HO‑1/CYP1A2 interaction.  CYP1A2 formed a physical complex with HO-1 that was stable in the presence of POR.  As expected, both HO‑1 and CYP1A2 formed BRET-detectable complexes with POR.  Whereas the POR•CYP1A2 complex was readily disrupted by the addition of HO‑1, the POR•HO-1 complex was not significantly affected by the addition of CYP1A2.  Interestingly, enzyme activities did not follow this pattern.  Whereas BRET data suggested substantial inhibition of CYP1A2-mediated 7-ethoxyresorufin deethylation in the presence of HO-1, its activity was actually stimulated at subsaturating POR.  In contrast, HO‑1-mediated heme metabolism was inhibited at subsaturating POR.  These results indicate that HO‑1 and CYP1A2 form a stable complex and have mutual effects on the catalytic behavior of both proteins that cannot be explained by simple competition for POR.

scholarly journals Heme oxygenase-1 affects cytochrome P450 function through the formation of heteromeric complexes: Interactions between CYP1A2 and heme oxygenase-1

2020 ◽  
Author(s):  
J. Patrick Connick ◽  
James R. Reed ◽  
George F. Cawley ◽  
Wayne L. Backes
Keyword(s):  
Cytochrome P450 ◽  
Heme Oxygenase ◽  
Cytochromes P450 ◽  
Resonance Energy Transfer ◽  
Resonance Energy ◽  
Stable Complex ◽  
Heme Oxygenase 1 ◽  
Cytochrome P450 Reductase ◽  
Xenobiotic Exposure ◽  
Substantial Inhibition

AbstractHeme oxygenase 1 (HO-1) and the cytochromes P450 (P450s) are endoplasmic reticulum-bound enzymes that rely on the same protein, NADPH-cytochrome P450 reductase (POR), to provide the electrons necessary for substrate metabolism. Although the HO-1 and P450 systems are interconnected due to their common electron donor, they generally have been studied separately. As the expression of both HO-1 and P450s are affected by xenobiotic exposure, changes in HO-1 expression can potentially affect P450 function, and conversely, changes in P450 expression can influence HO-1. The goal of this study was to examine interactions between the P450 and HO-1 systems. Using bioluminescence resonance energy transfer (BRET), HO-1 formed HO-1•P450 complexes with CYP1A2, CYP1A1, and CYP2D6, but not all P450s. Studies then focused on the HO-1/CYP1A2 interaction. CYP1A2 formed a physical complex with HO-1 that was stable in the presence of POR. As expected, both HO-1 and CYP1A2 formed BRET-detectable complexes with POR. Whereas the POR•CYP1A2 complex was readily disrupted by the addition of HO-1, the POR•HO-1 complex was not significantly affected by the addition of CYP1A2. Interestingly, enzyme activities did not follow this pattern. Whereas BRET data suggested substantial inhibition of CYP1A2-mediated 7-ethoxyresorufin deethylation in the presence of HO-1, its activity was actually stimulated at subsaturating POR. In contrast, HO-1-mediated heme metabolism was inhibited at subsaturating POR. These results indicate that HO-1 and CYP1A2 form a stable complex and have mutual effects on the catalytic behavior of both proteins that cannot be explained by simple competition for POR.

Sign in / Sign up

Export Citation Format

Share Document