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France. djemel.hamdane@college-de-franc... Publications | LitMetric

7 results match your criteria: "France. djemel.hamdane@college-de-france.fr.[Affiliation]"

Ultrafast dynamics of fully reduced flavin in catalytic structures of thymidylate synthase ThyX.

Phys Chem Chem Phys

October 2021

PASTEUR, Département de chimie, École normale supérieure, PSL University, Sorbonne Université, CNRS, 75005 Paris, France.

Thymidylate is a vital DNA precursor synthesized by thymidylate synthases. ThyX is a flavin-dependent thymidylate synthase found in several human pathogens and absent in humans, which makes it a potential target for antimicrobial drugs. This enzyme methylates the 2'-deoxyuridine 5'-monophosphate (dUMP) to 2'-deoxythymidine 5'-monophosphate (dTMP) using a reduced flavin adenine dinucleotide (FADH) as prosthetic group and (6)-,-methylene-5,6,7,8-tetrahydrofolate (CHTHF) as a methylene donor.

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An enzymatic activation of formaldehyde for nucleotide methylation.

Nat Commun

July 2021

Laboratoire de Chimie des Processus Biologiques, CNRS-UMR 8229, Collège De France, Université Pierre et Marie Curie, Paris, France.

Folate enzyme cofactors and their derivatives have the unique ability to provide a single carbon unit at different oxidation levels for the de novo synthesis of amino-acids, purines, or thymidylate, an essential DNA nucleotide. How these cofactors mediate methylene transfer is not fully settled yet, particularly with regard to how the methylene is transferred to the methylene acceptor. Here, we uncovered that the bacterial thymidylate synthase ThyX, which relies on both folate and flavin for activity, can also use a formaldehyde-shunt to directly synthesize thymidylate.

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Power of protein/tRNA functional assembly against aberrant aggregation.

Phys Chem Chem Phys

October 2017

Laboratoire de Chimie des Processus Biologiques, CNRS-UMR 8229, Collège De France, Université Pierre et marie Curie, 11 place Marcelin Berthelot, 75231 Paris Cedex 05, France.

Understanding the mechanisms of protein oligomerization and aggregation is a major concern for biotechnology and medical purposes. However, significant challenges remain in determining the mechanism of formation of these superstructures and the environmental factors that can precisely modulate them. Notably the role that a functional ligand plays in the process of protein aggregation is largely unexplored.

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A chemical chaperone induces inhomogeneous conformational changes in flexible proteins.

Phys Chem Chem Phys

July 2016

Laboratoire de Chimie des Processus Biologiques, CNRS-UMR 8229, Collège De France, France 11 place Marcelin Berthelot, 75231 Paris Cedex 05, France.

Organic osmolytes also known as chemical chaperones are major cellular compounds that favor, by an unclear mechanism, protein's compaction and stabilization of the native state. Here, we have examined the chaperone effect of the naturally occurring trimethylamine N-oxide (TMAO) osmolyte on a loosely packed protein (LPP), known to be a highly flexible form, using an apoprotein mutant of the flavin-dependent RNA methyltransferase as a model. Thermal and chemical denaturation experiments showed that TMAO stabilizes the structural integrity of the apoprotein dramatically.

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An extended dsRBD is required for post-transcriptional modification in human tRNAs.

Nucleic Acids Res

October 2015

Laboratoire de Chimie des Processus Biologiques, CNRS-UMR 8229, Collège De France, France, 11 place Marcelin Berthelot, 75231 Paris Cedex 05, France

In tRNA, dihydrouridine is a conserved modified base generated by the post-transcriptional reduction of uridine. Formation of dihydrouridine 20, located in the D-loop, is catalyzed by dihydrouridine synthase 2 (Dus2). Human Dus2 (HsDus2) expression is upregulated in lung cancers, offering a growth advantage throughout its ability to interact with components of the translation apparatus and inhibit apoptosis.

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Dynamics of RNA modification by a multi-site-specific tRNA methyltransferase.

Nucleic Acids Res

October 2014

Laboratoire d'Enzymologie et Biochimie Structurales, Centre de Recherche de Gif, CNRS, 1 avenue de la Terrasse, 91198 Gif-sur-Yvette, France Laboratoire de Chimie des Processus Biologiques, Collège de France, CNRS, 11 place Marcelin Berthelot, 75231 Paris Cedex 05, France

In most organisms, the widely conserved 1-methyl-adenosine58 (m1A58) tRNA modification is catalyzed by an S-adenosyl-L-methionine (SAM)-dependent, site-specific enzyme TrmI. In archaea, TrmI also methylates the adjacent adenine 57, m1A57 being an obligatory intermediate of 1-methyl-inosine57 formation. To study this multi-site specificity, we used three oligoribonucleotide substrates of Pyrococcus abyssi TrmI (PabTrmI) containing a fluorescent 2-aminopurine (2-AP) at the two target positions and followed the RNA binding kinetics and methylation reactions by stopped-flow and mass spectrometry.

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FAD/folate-dependent tRNA methyltransferase: flavin as a new methyl-transfer agent.

J Am Chem Soc

December 2012

Laboratoire de Chimie des Processus Biologiques, CNRS-FRE 3488, Collège De France, 11 place Marcelin Berthelot, 75231 Paris Cedex 05, France.

RNAs contain structurally and functionally important modified nucleosides. Methylation, the most frequent RNA modification in all living organisms, mostly relies on SAM (S-adenosylmethionine)-dependent methyltransferases. TrmFO was recently discovered as a unique tRNA methyltransferase using instead methylenetetrahydrofolate and reduced flavin adenine dinucleotide (FAD) as essential cofactors, but its mechanism has remained elusive.

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