Author
Lutz Schmitt
Other affiliations: University of Paris, University of Marburg, Goethe University Frankfurt ...read more
Bio: Lutz Schmitt is an academic researcher from University of Düsseldorf. The author has contributed to research in topics: ATP-binding cassette transporter & Secretion. The author has an hindex of 42, co-authored 182 publications receiving 6144 citations. Previous affiliations of Lutz Schmitt include University of Paris & University of Marburg.
Papers published on a yearly basis
Papers
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TL;DR: This work proposes a new classification into six clusters of substrate‐binding proteins, based on features of their three‐dimensional structure, and divides these proteins into three structural classes and two functional classes.
476 citations
TL;DR: The hypothesis that substrate‐assisted catalysis, rather than general base catalysis might operate in ABC‐ATPases is discussed, based on biochemical experiments, and proposed model in which E631 and H662, highly conserved among ABC transporters, form a catalytic dyad.
Abstract: The ABC transporter HlyB is a central element of the HlyA secretion machinery, a paradigm of Type I secretion. Here, we describe the crystal structure of the HlyB‐NBD (nucleotide‐binding domain) with H662 replaced by Ala in complex with ATP/Mg 2+ . The dimer shows a composite architecture, in which two intact ATP molecules are bound at the interface of the Walker A motif and the C‐loop, provided by the two monomers. ATPase measurements confirm that H662 is essential for activity. Based on these data, we propose a model in which E631 and H662, highly conserved among ABC transporters, form a catalytic dyad. Here, H662 acts as a ‘linchpin’, holding together all required parts of a complicated network of interactions between ATP, water molecules, Mg 2+ , and amino acids both in cis and trans , necessary for intermonomer communication. Based on biochemical experiments, we discuss the hypothesis that substrate‐assisted catalysis, rather than general base catalysis might operate in ABC‐ATPases.
340 citations
University of Granada1, ETH Zurich2, University of Illinois at Urbana–Champaign3, University of Groningen4, University of Utah5, University of Potsdam6, University of Tokyo7, University of Jaén8, University College Cork9, Seoul National University10, University of Glasgow11, University of Denver12, Princeton University13, Spanish National Research Council14, University of Grenoble15, National Museum of Natural History16, University of Bonn17, Panjab University, Chandigarh18, University of Düsseldorf19, Skolkovo Institute of Science and Technology20, Technical University of Berlin21, John Innes Centre22, Nanjing University23, Massachusetts Institute of Technology24, Leiden University25, Fudan University26, Chinese Academy of Sciences27
TL;DR: The review discusses the new classes of RiPPs that have been discovered, the advances in the understanding of the installation of both primary and secondary post-translational modifications, and the mechanisms by which the enzymes recognize the leader peptides in their substrates.
318 citations
TL;DR: Recently determined structures of full-length ABC transporters and isolated ABC domains have increased the understanding of the functional mechanism of these proteins.
301 citations
TL;DR: While recent structural studies of TolC and MFP-like proteins are providing atomic detail of much of the transport path, structural analysis of the HlyB NBD and other ABC ATPases have revealed details of the catalytic cycle within an NBD dimer and a glimpse of how the action of Hly B is coupled to the translocation of HlA.
Abstract: The relatively simple type 1 secretion system in gram-negative bacteria is nevertheless capable of transporting polypeptides of up to 800 kDa across the cell envelope in a few seconds. The translocator is composed of an ABC-transporter, providing energy through ATP hydrolysis (and perhaps the initial channel across the inner membrane), linked to a multimeric Membrane Fusion Protein (MFP) spanning the initial part of the periplasm and forming a continuous channel to the surface with an outer membrane trimeric protein. Proteins targeted to the translocator carry an (uncleaved), poorly conserved secretion signal of approximately 50 residues. In E. coli the HlyA toxin interacts with both the MFP (HlyD) and the ABC protein HlyB, (a half transporter) triggering, via a conformational change in HlyD, recruitment of the third component, TolC, into the transenvelope complex. In vitro, HlyA, through its secretion signal, binds to the nucleotide binding domain (NBD or ABC-ATPase) of HlyB in a reaction reversible by ATP that may mimic initial movement of HlyA into the translocation channel. HlyA is then transported rapidly, apparently in an unfolded form, to the cell surface, where folding and release takes place. Whilst recent structural studies of TolC and MFP-like proteins are providing atomic detail of much of the transport path, structural analysis of the HlyB NBD and other ABC ATPases, have revealed details of the catalytic cycle within an NBD dimer and a glimpse of how the action of HlyB is coupled to the translocation of HlyA.
258 citations
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TL;DR: Supporting lipid-protein bilayers form versatile models of low-dimensionality complex fluids, which can be used to study interfacial forces and wetting phenomena, and enable the design of phantom cells to explore the interplay of lock-and-key forces and universal forces for cell adhesion.
Abstract: Scientific and practical applications of supported lipid-protein bilayers are described. Membranes can be covalently coupled to or separated from solids by ultrathin layers of water or soft polymer cushions. The latter systems maintain the structural and dynamic properties of free bilayers, forming a class of models of biomembranes that allow the application of a manifold of surface-sensitive techniques. They form versatile models of low-dimensionality complex fluids, which can be used to study interfacial forces and wetting phenomena, and enable the design of phantom cells to explore the interplay of lock-and-key forces (such as receptor-ligand binding) and universal forces for cell adhesion. Practical applications are the design of (highly selective) receptor surfaces of biosensors on electrooptical devices or the biofunctionalization of inorganic solids.
2,123 citations
TL;DR: An approach combining the analysis of signature protein families and features of the architecture of cas loci that unambiguously partitions most CRISPR–cas loci into distinct classes, types and subtypes is presented.
Abstract: The evolution of CRISPR-cas loci, which encode adaptive immune systems in archaea and bacteria, involves rapid changes, in particular numerous rearrangements of the locus architecture and horizontal transfer of complete loci or individual modules. These dynamics complicate straightforward phylogenetic classification, but here we present an approach combining the analysis of signature protein families and features of the architecture of cas loci that unambiguously partitions most CRISPR-cas loci into distinct classes, types and subtypes. The new classification retains the overall structure of the previous version but is expanded to now encompass two classes, five types and 16 subtypes. The relative stability of the classification suggests that the most prevalent variants of CRISPR-Cas systems are already known. However, the existence of rare, currently unclassifiable variants implies that additional types and subtypes remain to be characterized.
1,988 citations
Journal Article•
TL;DR: In this paper, a genotypic screen was developed to identify a heterozygous recessive mutation at the URA3 locus, which was introduced by targeted mutagenesis, homologous integration of transforming DNA, to avoid introduction of extraneous mutations.
1,595 citations
TL;DR: This work focuses on three topics: ABC transporters transporting drugs (xenotoxins) and drug conjugates, and a rapidly increasing number of ABC Transporters found to play a role in lipid transport.
Abstract: The ATP-binding cassette (ABC) transporters are a family of large proteins in membranes and are able to transport a variety of compounds through membranes against steep concentration gradients at the cost of ATP hydrolysis. The available outline of the human genome contains 48 ABC genes; 16 of these have a known function and 14 are associated with a defined human disease. Major physiological functions of ABC transporters include the transport of lipids, bile salts, toxic compounds, and peptides for antigen presentation or other purposes. We review the functions of mammalian ABC transporters, emphasizing biochemical mechanisms and genetic defects. Our overview illustrates the importance of ABC transporters in human physiology, toxicology, pharmacology, and disease. We focus on three topics: (a) ABC transporters transporting drugs (xenotoxins) and drug conjugates. (b) Mammalian secretory epithelia using ABC transporters to excrete a large number of substances, sometimes against a steep concentration gradient. Several inborn errors in liver metabolism are due to mutations in one of the genes for these pumps; these are discussed. (c) A rapidly increasing number of ABC transporters are found to play a role in lipid transport. Defects in each of these transporters are involved in human inborn or acquired diseases.
1,524 citations