scholarly journals Structural basis of carnitine monooxygenase CntA substrate specificity, inhibition and inter-subunit electron transfer

2020 ◽  
pp. jbc.RA120.016019
Author(s):  
Mussa Quareshy ◽  
Muralidharan Shanmugam ◽  
Eleanor Townsend ◽  
Eleanor Jameson ◽  
Timothy D.H. Bugg ◽  
...  
Keyword(s):  
Electron Transfer ◽  
Molecular Basis ◽  
Drug Targets ◽  
Structural Basis ◽  
Paramagnetic Resonance ◽  
Group V ◽  
Mononuclear Iron ◽  
Quaternary Ammonium Group ◽  
Accelerate Atherosclerosis ◽  
Rieske Oxygenases

Microbial metabolism of carnitine to trimethylamine (TMA) in the gut can accelerate atherosclerosis and heart disease and these TMA-producing enzymes are therefore important drug targets. Here, we report the first structures of the carnitine oxygenase CntA, an enzyme of the Rieske oxygenase family. CntA exists in a head-to-tail a3 trimeric structure. The two functional domains (the Rieske and the catalytic mononuclear iron domains) are located > 40 Å apart in the same monomer but adjacent in two neighbouring monomers. Structural determination of CntA and subsequent electron paramagnetic resonance measurements uncover the molecular basis of the so-called bridging glutamate (E205) residue in inter-subunit electron transfer. The structures of the substrate-bound CntA help to define the substrate pocket. Importantly, a tyrosine residue (Y203) is essential for ligand recognition through a π-cation interaction with the quaternary ammonium group. This interaction between an aromatic residue and quaternary amine substrates allows us to delineate a subgroup of Rieske oxygenases (group V) from the prototype ring-hydroxylating Rieske oxygenases involved in bioremediation of aromatic pollutants in the environment. Furthermore, we report the discovery of the first known CntA inhibitors and solve the structure of CntA in complex with the inhibitor, demonstrating the pivotal role of Y203 through a π-π stacking interaction with the inhibitor. Our study provides the structural and molecular basis for future discovery of drugs targeting this TMA-producing enzyme in human gut.

scholarly journals An electron transfer competent structural ensemble of membrane-bound cytochrome P450 1A1 and cytochrome P450 oxidoreductase

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Goutam Mukherjee ◽  
Prajwal P. Nandekar ◽  
Rebecca C. Wade
Keyword(s):  
Electron Transfer ◽  
Cytochrome P450 ◽  
Drug Targets ◽  
Catalytic Domain ◽  
Cytochrome P450 1A1 ◽  
P450 Oxidoreductase ◽  
Distal Side ◽  
Cytochrome P450 Oxidoreductase ◽  
Membrane Bound ◽  
Transient Interactions

AbstractCytochrome P450 (CYP) heme monooxygenases require two electrons for their catalytic cycle. For mammalian microsomal CYPs, key enzymes for xenobiotic metabolism and steroidogenesis and important drug targets and biocatalysts, the electrons are transferred by NADPH-cytochrome P450 oxidoreductase (CPR). No structure of a mammalian CYP–CPR complex has been solved experimentally, hindering understanding of the determinants of electron transfer (ET), which is often rate-limiting for CYP reactions. Here, we investigated the interactions between membrane-bound CYP 1A1, an antitumor drug target, and CPR by a multiresolution computational approach. We find that upon binding to CPR, the CYP 1A1 catalytic domain becomes less embedded in the membrane and reorients, indicating that CPR may affect ligand passage to the CYP active site. Despite the constraints imposed by membrane binding, we identify several arrangements of CPR around CYP 1A1 that are compatible with ET. In the complexes, the interactions of the CPR FMN domain with the proximal side of CYP 1A1 are supplemented by more transient interactions of the CPR NADP domain with the distal side of CYP 1A1. Computed ET rates and pathways agree well with available experimental data and suggest why the CYP–CPR ET rates are low compared to those of soluble bacterial CYPs.

scholarly journals Molecular Basis for Directional Electron Transfer

2010 ◽  
Vol 285 (14) ◽  
pp. 10370-10375 ◽  
Author(s):  
Catarina M. Paquete ◽  
Ivo H. Saraiva ◽  
Eduardo Calçada ◽  
Ricardo O. Louro
Keyword(s):  
Electron Transfer ◽  
Molecular Basis

scholarly journals Structural basis for ligand and innate immunity factor uptake by the trypanosome haptoglobin-haemoglobin receptor

eLife ◽  
2014 ◽  
Vol 3 ◽  
Author(s):  
Harriet Lane-Serff ◽  
Paula MacGregor ◽  
Edward D Lowe ◽  
Mark Carrington ◽  
Matthew K Higgins
Keyword(s):  
Innate Immunity ◽  
Trypanosoma Brucei ◽  
Molecular Basis ◽  
Structural Basis ◽  
Β Subunit ◽  
Trypanosome Infection ◽  
Lateral Mobility ◽  
African Trypanosomes ◽  
Distal Half ◽  
Immunity Factor

The haptoglobin-haemoglobin receptor (HpHbR) of African trypanosomes allows acquisition of haem and provides an uptake route for trypanolytic factor-1, a mediator of innate immunity against trypanosome infection. In this study, we report the structure of Trypanosoma brucei HpHbR in complex with human haptoglobin-haemoglobin (HpHb), revealing an elongated ligand-binding site that extends along its membrane distal half. This contacts haptoglobin and the β-subunit of haemoglobin, showing how the receptor selectively binds HpHb over individual components. Lateral mobility of the glycosylphosphatidylinositol-anchored HpHbR, and a ∼50o kink in the receptor, allows two receptors to simultaneously bind one HpHb dimer. Indeed, trypanosomes take up dimeric HpHb at significantly lower concentrations than monomeric HpHb, due to increased ligand avidity that comes from bivalent binding. The structure therefore reveals the molecular basis for ligand and innate immunity factor uptake by trypanosomes and identifies adaptations that allow efficient ligand uptake in the context of the complex trypanosome cell surface.

scholarly journals Structural basis of GTPase-mediated mitochondrial ribosome biogenesis and recycling

2021 ◽  
Author(s):  
Hauke S. Hillen ◽  
Elena Lavdovskaia ◽  
Franziska Nadler ◽  
Elisa Hanitsch ◽  
Andreas Linden ◽  
...  
Keyword(s):  
Molecular Basis ◽  
Ribosomal Proteins ◽  
Ribosome Biogenesis ◽  
Large Subunit ◽  
Structural Basis ◽  
Catalytic Core ◽  
Mitochondrial Ribosomes ◽  
Mitochondrial Ribosome ◽  
Translation Systems

Ribosome biogenesis is an essential process that requires auxiliary factors to promote folding and assembly of ribosomal proteins and RNA. In particular, maturation of the peptidyl transferase center (PTC), the catalytic core of the ribosome, is mediated by universally conserved GTPases, but the molecular basis is poorly understood. Here, we define the mechanism of GTPase-driven maturation of the human mitochondrial ribosomal large subunit (mtLSU) using a combination of endogenous complex purification, in vitro reconstitution and cryo-electron microscopy (cryo-EM). Structures of transient native mtLSU assembly intermediates that accumulate in GTPBP6-deficient cells reveal how the biogenesis factors GTPBP5, MTERF4 and NSUN4 facilitate PTC folding. Subsequent addition of recombinant GTPBP6 reconstitutes late mtLSU biogenesis in vitro and shows that GTPBP6 triggers a molecular switch by releasing MTERF4-NSUN4 and GTPBP5 accompanied by the progression to a near-mature PTC state. In addition, cryo-EM analysis of GTPBP6-treated mature mitochondrial ribosomes reveals the structural basis for the dual-role of GTPBP6 in ribosome biogenesis and recycling. Together, these results define the molecular basis of dynamic GTPase-mediated PTC maturation during mitochondrial ribosome biogenesis and provide a framework for understanding step-wise progression of PTC folding as a critical quality control checkpoint in all translation systems.

scholarly journals Molecular basis for chirality-regulated Aβ self-assembly and receptor recognition revealed by ion mobility-mass spectrometry

2019 ◽  
Vol 10 (1) ◽  
Author(s):  
Gongyu Li ◽  
Kellen DeLaney ◽  
Lingjun Li
Keyword(s):  
Mass Spectrometry ◽  
Ion Mobility ◽  
Self Assembly ◽  
Molecular Basis ◽  
Drug Targets ◽  
Molecular Evidence ◽  
Ion Mobility Mass Spectrometry ◽  
Epitope Region ◽  
Receptor Recognition ◽  
Chiral Effects

Abstract Despite extensive efforts on probing the mechanism of Alzheimer’s disease (AD) and enormous investments into AD drug development, the lack of effective disease-modifying therapeutics and the complexity of the AD pathogenesis process suggest a great need for further insights into alternative AD drug targets. Herein, we focus on the chiral effects of truncated amyloid beta (Aβ) and offer further structural and molecular evidence for epitope region-specific, chirality-regulated Aβ fragment self-assembly and its potential impact on receptor-recognition. A multidimensional ion mobility-mass spectrometry (IM-MS) analytical platform and in-solution kinetics analysis reveal the comprehensive structural and molecular basis for differential Aβ fragment chiral chemistry, including the differential and cooperative roles of chiral Aβ N-terminal and C-terminal fragments in receptor recognition. Our method is applicable to many other systems and the results may shed light on the potential development of novel AD therapeutic strategies based on targeting the D-isomerized Aβ, rather than natural L-Aβ.

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