Sander H. J. Smits

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Substrate-binding proteins (SBP) are associated with a wide variety of protein complexes. The proteins are part of ATP-binding cassette transporters for substrate uptake, ion gradient driven transporters, DNA-binding proteins, as well as channels and receptors from both pro- and eukaryotes. A wealth of structural and functional data is available on SBPs,(More)
Nisin is a model system for lantibiotics, a class of peptides displaying antimicrobial activity against various Gram-positive bacteria. After ribosomal synthesis, the precursor peptide is modified in two steps, of which the last one involves consecutive cyclization reactions mediated by the cyclase NisC. Here, we present a detailed in vitro study of the(More)
Integral membrane proteins are involved in virtually every cellular process. Precisely regulating these machineries would allow controlling many human and vertebrate diseases. Embedded into cellular membranes, membrane proteins establish molecular interactions that sensitively react to environmental changes and to molecular compounds, such as ligands or(More)
Bacillus subtilis can synthesize the compatible solute glycine betaine as an osmoprotectant from an exogenous supply of the precursor choline. Import of choline is mediated by two osmotically inducible ABC transport systems: OpuB and OpuC. OpuC catalyzes the import of various osmoprotectants, whereas OpuB is highly specific for choline. OpuBC is the(More)
The LrpA protein from the hyperthermophilic archaeon Pyrococcus furiosus belongs to the Lrp/AsnC family of transcriptional regulatory proteins, of which the Escherichia coli leucine-responsive regulatory protein is the archetype. Its crystal structure has been determined at 2.9 A resolution and is the first for a member of the Lrp/AsnC family, as well as(More)
Lantibiotics are small peptides produced by Gram-positive bacteria, which are ribosomally synthesized as a prepeptide. Their genes are highly organized in operons containing all the genes required for maturation, transport, immunity and synthesis. The best-characterized lantibiotic is nisin from Lactococcus lactis. Nisin is active against other(More)
Nisin is an antimicrobial peptide produced and secreted by several L. lactis strains and is specifically active against Gram-positive bacteria. In previous studies, nisin was purified via cation exchange chromatography at low pH employing a single-step elution using 1 M NaCl. Here, we describe an optimized purification protocol using a five-step NaCl(More)
Ectoine and hydroxyectoine are well-recognized members of the compatible solutes and are widely employed by microorganisms as osmostress protectants. The EctABC enzymes catalyze the synthesis of ectoine from the precursor L-aspartate-β-semialdehyde. A subgroup of the ectoine producers can convert ectoine into 5-hydroxyectoine through a region-selective and(More)
Type 1 secretion systems are one of the main machineries in Gram-negative bacteria involved in the secretion of a wide range of substrates from the cytoplasm across the inner and outer membrane in one step to the extracellular space. The range of substrates varies from small proteins up to large surface layer proteins of about 900 kDa. Most of the(More)
The ATP-binding cassette transporter ChoVWX is one of several choline import systems operating in Sinorhizobium meliloti. Here fluorescence-based ligand binding assays were used to quantitate substrate binding by the periplasmic ligand-binding protein ChoX. These data confirmed that ChoX recognizes choline and acetylcholine with high and medium affinity,(More)