The Experts below are selected from a list of 48432 Experts worldwide ranked by ideXlab platform
Damian Ekiert - One of the best experts on this subject based on the ideXlab platform.
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Structural and functional diversity calls for a new classification of ABC transporters
2020Co-Authors: Christoph Thomas, Stephen G. Aller, Konstantinos Beis, Elisabeth P. Carpenter, Geoffrey Chang, Lei Chen, Elie Dassa, Michel Dean, Franck Duong Van Hoa, Damian EkiertAbstract:Members of the ATP-binding cassette (ABC) transporter superfamily translocate a broad spectrum of chemically diverse substrates. While their eponymous ATP-binding cassette in the nucleotide-binding domains (NBDs) is highly conserved, their transmembrane domains (TMDs) forming the translocation pathway exhibit distinct folds and topologies, suggesting that during evolution, the ancient motor domains were combined with different transmembrane mechanical systems to orchestrate a variety of cellular processes. In recent years, it has become increasingly evident that the distinct TMD folds are best suited to categorize the multitude of ABC transporters. We therefore propose a new ABC transporter classification that currently comprises seven different types based on Structural Homology in the TMDs.
John S Blanchard - One of the best experts on this subject based on the ideXlab platform.
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crystal structure of mycothiol synthase rv0819 from mycobacterium tuberculosis shows Structural Homology to the gnat family of n acetyltransferases
2003Co-Authors: M W Vetting, Steven L Roderick, John S BlanchardAbstract:Mycothiol is the predominant low-molecular weight thiol produced by actinomycetes, including Mycobacterium tuberculosis. The last reaction in the biosynthetic pathway for mycothiol is catalyzed by mycothiol synthase (MshD), which acetylates the cysteinyl amine of cysteine–glucosamine–inositol (Cys–GlcN–Ins). The crystal structure of MshD was determined in the presence of coenzyme A and acetyl–CoA . MshD consists of two tandem-repeated domains, each exhibiting the Gcn5-related N-acetyltransferase (GNAT) fold. These two domains superimpose with a root-mean-square deviation of 1.7 A over 88 residues, and each was found to bind one molecule of coenzyme, although the binding sites are quite different. The C-terminal domain has a similar active site to many GNAT members in which the acetyl group of the coenzyme is presented to an open active site slot. However, acetyl–CoA bound to the N-terminal domain is buried, and is apparently not positioned to promote acetyl transfer. A modeled substrate complex indicates that Cys–GlcN–Ins would only fill a portion of a negatively charged channel located between the two domains. This is the first structure determined for an enzyme involved in the biosynthesis of mycothiol.
Stephen W White - One of the best experts on this subject based on the ideXlab platform.
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the crystal structure of ribosomal protein s4 reveals a two domain molecule with an extensive rna binding surface one domain shows Structural Homology to the ets dna binding motif
1998Co-Authors: Christopher Davies, Resi B Gerstner, David E Draper, V Ramakrishnan, Stephen W WhiteAbstract:We report the 1.7 A crystal structure of ribosomal protein S4 from Bacillus stearothermophilus. To facilitate the crystallization, 41 apparently flexible residues at the N-terminus of the protein have been deleted (S4Delta41). S4Delta41 has two domains; domain 1 is completely alpha-helical and domain 2 comprises a five-stranded antiparallel beta-sheet with three alpha-helices packed on one side. Domain 2 is an insertion within domain 1, and it shows significant Structural Homology to the ETS domain of eukaryotic transcription factors. A phylogenetic analysis of the S4 primary structure shows that the likely RNA interaction surface is predominantly on one side of the protein. The surface is extensive and highly positively charged, and is centered on a distinctive canyon at the domain interface. The latter feature contains two arginines that are totally conserved in all known species of S4 including eukaryotes, and are probably crucial in binding RNA. As has been shown for other ribosomal proteins, mutations within S4 that affect ribosome function appear to disrupt the RNA-binding sites. The structure provides a framework with which to probe the RNA-binding properties of S4 by site-directed mutagenesis.
Christoph Thomas - One of the best experts on this subject based on the ideXlab platform.
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Structural and functional diversity calls for a new classification of ABC transporters
2020Co-Authors: Christoph Thomas, Stephen G. Aller, Konstantinos Beis, Elisabeth P. Carpenter, Geoffrey Chang, Lei Chen, Elie Dassa, Michel Dean, Franck Duong Van Hoa, Damian EkiertAbstract:Members of the ATP-binding cassette (ABC) transporter superfamily translocate a broad spectrum of chemically diverse substrates. While their eponymous ATP-binding cassette in the nucleotide-binding domains (NBDs) is highly conserved, their transmembrane domains (TMDs) forming the translocation pathway exhibit distinct folds and topologies, suggesting that during evolution, the ancient motor domains were combined with different transmembrane mechanical systems to orchestrate a variety of cellular processes. In recent years, it has become increasingly evident that the distinct TMD folds are best suited to categorize the multitude of ABC transporters. We therefore propose a new ABC transporter classification that currently comprises seven different types based on Structural Homology in the TMDs.
Ellis L Reinherz - One of the best experts on this subject based on the ideXlab platform.
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the high affinity fc epsilon receptor gamma subunit fc epsilon ri gamma facilitates t cell receptor expression and antigen major histocompatibility complex driven signaling in the absence of cd3 zeta and cd3 eta
1991Co-Authors: Hans Reimer Rodewald, Antonio R N Arulanandam, Shigeo Koyasu, Ellis L ReinherzAbstract:The T cell receptor (TCR) is a molecular complex formed by at least seven transmembrane proteins: the antigen/major histocompatibility complex recognition unit (Ti alpha-beta heterodimer) and the invariant CD3 chains (gamma, delta, epsilon, zeta, and eta). In addition to targeting partially assembled Ti alpha-beta CD3 gamma delta epsilon TCR complexes to the cell surface, CD3 zeta appears to be essential for interleukin-2 production after TCR stimulation with antigen/major histocompatibility complex. The gamma chain of the high affinity Fc receptor for IgE (Fc epsilon RI gamma) has significant Structural Homology to CD3 zeta and the related CD3 eta subunit. To identify the functional significance of sequence homologies between CD3 zeta and Fc epsilon RI gamma in T cells, we have transfected a Fc epsilon RI gamma cDNA into a T cell hybridoma lacking CD3 zeta and CD3 eta proteins. Herein we show that a Fc epsilon RI gamma-gamma homodimer associates with TCR components to up-regulate TCR surface expression. A TCR composed of Ti alpha-beta CD3 gamma delta epsilon Fc epsilon RI gamma-gamma is sufficient to restore the coupling of TCR antigen recognition to the interleukin-2 induction pathway, demonstrating the functional significance of Structural Homology between the above receptor subunits. These results, in conjunction with the recent finding that CD3 zeta, CD3 eta, and Fc epsilon RI gamma are coexpressed in certain T cells as subunits of an unusual TCR isoform, suggest that Fc epsilon RI gamma is likely to play a role in T cell lineage function.
