Jan Steyaert

Jan Steyaert
Vrije Universiteit Brussel | VUB · Structural Biology Brussels (SBB)

Professor Structural Biology

About

312
Publications
56,883
Reads
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15,753
Citations
Additional affiliations
January 2011 - present
Vlaams Instituut voor Biotechnologie
Position
  • Vice-director of the VIB structural Biology department
September 2010 - present
Vrije Universiteit Brussel
Position
  • Director of the VUB department for Structural Biology
January 1998 - present
Vlaams Instituut voor Biotechnologie
Position
  • Groupleader at VIB

Publications

Publications (312)
Article
Full-text available
Proton-coupled Oligopeptide Transporters (POTs) of the Major Facilitator Superfamily (MFS) mediate the uptake of short di- and tripeptides in all phyla of life. POTs are thought to constitute the most promiscuous class of MFS transporters, with the potential to transport more than 8400 unique substrates. Over the past two decades, transport assays...
Article
Full-text available
The liver takes up bile salts from blood to generate bile, enabling absorption of lipophilic nutrients and excretion of metabolites and drugs1. Human Na+–taurocholate co-transporting polypeptide (NTCP) is the main bile salt uptake system in liver. NTCP is also the cellular entry receptor of human hepatitis B and D viruses2,3 (HBV/HDV), and has emer...
Article
Full-text available
The integrity of a cell’s proteome depends on correct folding of polypeptides by chaperonins. The chaperonin TCP-1 ring complex (TRiC) acts as obligate folder for >10% of cytosolic proteins, including he cytoskeletal proteins actin and tubulin. Although its architecture and how it recognizes folding substrates are emerging from structural studies,...
Article
Binding of an extracellular signaling molecule to a G protein-coupled receptor (GPCR) results in G protein activation, which in turn triggers the production of second messengers. Although many advances have been achieved in understanding GPCR activation, the early steps of GPCR of this process are still poorly understood. In the case of rhodopsin,...
Preprint
Proton-coupled Oligopeptide Transporters (POTs) of the Major Facilitator Superfamily (MFS) mediate the uptake of short di- and tripeptides in all phyla of life. POTs are thought to constitute the most promiscuous class of MFS transporters, with the potential to transport more than 8400 unique substrates. Over the past two decades, transport assays...
Article
Full-text available
Hyaluronan is an acidic heteropolysaccharide comprising alternating N-acetylglucosamine and glucuronic acid sugars that is ubiquitously expressed in the vertebrate extracellular matrix¹. The high-molecular-mass polymer modulates essential physiological processes in health and disease, including cell differentiation, tissue homeostasis and angiogene...
Article
Full-text available
Significance Parkinson’s disease (PD) is the second-most common neurodegenerative disorder. Mutations leading to overactivation of LRRK2 are a leading cause of familial PD, and this protein is therefore considered as an appealing target for drug design. Here, we describe the discovery and characterization of a diverse set of LRRK2-targeting nanobod...
Article
Full-text available
Fast synaptic communication requires receptors that respond to the presence of neurotransmitter by opening an ion channel across the post-synaptic membrane. The muscle-type nicotinic acetylcholine receptor from the electric fish, Torpedo, is the prototypic ligand-gated ion channel, yet the structural changes underlying channel activation remain und...
Article
Full-text available
Influenza A viruses cause seasonal epidemics and global pandemics, representing a considerable burden to healthcare systems. Central to the replication cycle of influenza viruses is the viral RNA-dependent RNA polymerase which transcribes and replicates the viral RNA genome. The polymerase undergoes conformational rearrangements and interacts with...
Article
Full-text available
The Sonic Hedgehog (SHH) morphogen pathway is fundamental for embryonic development and stem cell maintenance and is implicated in various cancers. A key step in signaling is transfer of a palmitate group to the SHH N terminus, catalyzed by the multi-pass transmembrane enzyme Hedgehog acyltransferase (HHAT). We present the high-resolution cryo-EM s...
Article
Full-text available
With conformation-specific nanobodies being used for a wide range of structural, biochemical, and cell biological applications, there is a demand for antigen-binding fragments (Fabs) that specifically and tightly bind these nanobodies without disturbing the nanobody–target protein interaction. Here, we describe the development of a synthetic Fab (t...
Article
Full-text available
paaR2 – paaA2 – parE2 is a three-component toxin–antitoxin module found in prophage CP-993P of Escherichia coli O157:H7. Transcription regulation of this module occurs via the 123-amino-acid regulator PaaR2, which forms a large oligomeric structure. Despite appearing to be well folded, PaaR2 withstands crystallization, as does its N-terminal DNA-bi...
Article
Full-text available
The cystic fibrosis transmembrane conductance regulator (CFTR) anion channel is essential to maintain fluid homeostasis in key organs. Functional impairment of CFTR due to mutations in the cftr gene leads to cystic fibrosis. Here, we show that the first nucleotide-binding domain (NBD1) of CFTR can spontaneously adopt an alternate conformation that...
Preprint
Full-text available
Mutations in the gene coding for Leucine-Rich Repeat Kinase 2 (LRRK2) are a leading cause of the inherited form of Parkinson′s disease (PD), while LRRK2 overactivation is also associated with the more common idiopathic form of PD. LRRK2 is a large multi-domain protein, including a GTPase as well as a Ser/Thr protein kinase domain. Common disease-ca...
Preprint
Full-text available
With conformation-specific nanobodies being used for a wide range of structural, biochemical, and cell biological applications, there is a demand for antigen-binding fragments (Fabs) that specifically and tightly bind these nanobodies without disturbing the nanobody-target protein interaction. Here we describe the development of a synthetic Fab (te...
Article
Full-text available
The protein kinase Akt is one of the primary effectors of growth factor signaling in the cell. Akt responds specifically to the lipid second messengers phosphatidylinositol-3,4,5-trisphosphate [PI(3,4,5)P 3 ] and phosphatidylinositol-3,4-bisphosphate [PI(3,4)P 2 ] via its PH domain, leading to phosphorylation of its activation loop and the hydropho...
Article
Full-text available
Photoreceptors rely on distinct membrane compartments to support their specialized function. Unlike protein localization, identification of critical differences in membrane content has not yet been expanded to lipids, due to the difficulty of isolating domain-specific samples. We have overcome this by using SMA to coimmunopurify membrane proteins a...
Article
There is considerable interest in developing antibodies as modulators of signaling pathways. One of the most important signaling pathways in higher eukaryotes is the phosphoinositide 3-kinase (PI3K) pathway, which plays fundamental roles in growth, metabolism, and immunity. The class IB PI3K, PI3Kγ, is a heterodimeric complex composed of a catalyti...
Article
Full-text available
The class IB phosphoinositide 3-kinase (PI3K), PI3Kγ, is a master regulator of immune cell function and a promising drug target for both cancer and inflammatory diseases. Critical to PI3Kγ function is the association of the p110γ catalytic subunit to either a p101 or p84 regulatory subunit, which mediates activation by G protein–coupled receptors....
Preprint
Full-text available
The iconic Sonic Hedgehog (SHH) morphogen pathway is a fundamental orchestrator of embryonic development and stem cell maintenance, and is implicated in cancers in various organs. A key step in signalling is transfer of a palmitate group to the N-terminal cysteine residue of SHH, catalysed by the multi-pass transmembrane enzyme Hedgehog acyltransfe...
Article
Full-text available
Background: Nanobodies, or VHHs, are derived from heavy chain-only antibodies (hcAbs) found in camelids. They overcome some of the inherent limitations of monoclonal antibodies (mAbs) and derivatives thereof, due to their smaller molecular size and higher stability, and thus present an alternative to mAbs for therapeutic use. Two nanobodies, Nb23...
Preprint
Full-text available
The class IB phosphoinositide 3-kinase (PI3K), PI3Kγ, is a master regulator of immune cell function, and a promising drug target for both cancer and inflammatory diseases. Critical to PI3Kγ function is the association of the p110γ catalytic subunit to either a p101 or p84 regulatory subunit, which mediates activation by G-protein coupled receptors...
Preprint
Full-text available
There is considerable interest in developing antibodies as modulators of signaling pathways. One of the most important signaling pathways in higher eukaryotes is the phosphoinositide 3-kinase (PI3K) pathway, which plays fundamental roles in growth, metabolism and immunity. The class IB PI3K, PI3Kγ, is a heterodimeric complex composed of a catalytic...
Preprint
Full-text available
The integrity of a cell's proteome depends on correct folding of polypeptides by chaperonins. The TCP-1 ring chaperonin (TRiC) acts as obligate folder for >10% of cytosolic proteins, including cytoskeletal proteins actin and tubulin. While its architecture and how it recognises folding substrates is emerging from structural studies, the subsequent...
Preprint
Full-text available
Photoreceptors rely on distinct membrane compartments to support their specialized function. Unlike protein localization, identification of critical differences in membrane content has not yet been expanded to lipids, due to the difficulty of isolating domain-specific samples. We have overcome this by using SMA to co-immunopurify membrane proteins...
Article
Full-text available
Nanobodies are popular and versatile tools for structural biology. They have a compact single immunoglobulin domain organization, bind target proteins with high affinities while reducing their conformational heterogeneity and stabilize multi-protein complexes. Here we demonstrate that engineered nanobodies can also help overcome two major obstacles...
Article
Full-text available
Energy-coupling factor (ECF) transporters mediate import of micronutrients in prokaryotes. They consist of an integral membrane S-component (that binds substrate) and ECF module (that powers transport by ATP hydrolysis). It has been proposed that different S-components compete for docking onto the same ECF module, but a minimal liposome-reconstitut...
Article
Full-text available
Synaptojanin1 (Synj1) is a phosphoinositide phosphatase, important in clathrin uncoating during endocytosis of presynaptic vesicles. It was identified as a potential drug target for Alzheimer's disease, Down syndrome and TBC1D24-associated epilepsy, while also loss-of-function mutations in Synj1 are associated with epilepsy and Parkinson's disease....
Article
None of the current superresolution microscopy techniques can reliably image the changes in endogenous protein nanoclustering dynamics associated with specific conformations in live cells. Single-domain nanobodies have been invaluable tools to isolate defined conformational states of proteins, and we reasoned that expressing these nanobodies couple...
Preprint
Full-text available
The cystic fibrosis transmembrane conductance regulator (CFTR) anion channel is essential to maintain fluid homeostasis in key organs such as the lungs or the digestive systems. Functional impairment of CFTR due to mutation in the cftr gene lead to Cystic Fibrosis (CF) the most common lethal genetic disorder. Here we observe that the first nucleoti...
Article
Full-text available
Debates about the source of antibodies and their use are confusing two different issues. A ban on life immunization would have no repercussions on the quality of antibodies.
Article
Full-text available
VPS34 complex II (VPS34CII) is a 386-kDa assembly of the lipid kinase subunit VPS34 and three regulatory subunits that altogether function as a prototypical class III phosphatidylinositol-3-kinase (PI3K). When the active VPS34CII complex is docked to the cytoplasmic surface of endosomal membranes, it phosphorylates its substrate lipid (phosphatidyl...
Article
Full-text available
In this Article, the configuration of BU72 at the benzylic amine was mistakenly reported as (S). Re-fitting this stereocentre to (R) improved the fit of the observed density in the X-ray structure. The (S)-configuration was originally assigned on the basis of the expected stereochemistry from ref. 1. The origin of the inversion is unclear, but we p...
Preprint
Full-text available
Cystic Fibrosis (CF) is a common lethal genetic disorder caused by mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) anion channel. Misfolding and degradation of CFTR are the hallmarks of the predominant mutation, F508del, located in the first nucleotide binding domain (NBD1). While the mutation is known to affect the ther...
Article
Full-text available
The structure of lactose permease, stabilized in a periplasmic open conformation by two Gly to Trp replacements (LacYww) and complexed with a nanobody directed against this conformation, provides the highest resolution structure of the symporter. The nanobody binds in a different manner than two other nanobodies made against the same mutant, which...
Article
Full-text available
Mutations in the Parkinson’s disease (PD)-associated protein leucine-rich repeat kinase 2 (LRRK2) commonly lead to a reduction of GTPase activity and increase in kinase activity. Therefore, strategies for drug development have mainly been focusing on the design of LRRK2 kinase inhibitors. We recently showed that the central RocCOR domains (Roc: Ras...
Article
Full-text available
Recent studies show that GPCRs rapidly interconvert between multiple states although our ability to interrogate, monitor and visualize them is limited by a relative lack of suitable tools. We previously reported two nanobodies (Nb39 and Nb6) that stabilize distinct ligand- and efficacy-delimited conformations of the kappa opioid receptor. Here, we...
Article
Full-text available
Ric-8A is a cytosolic Guanine Nucleotide exchange Factor (GEF) that activates heterotrimeric G protein alpha subunits (Gα) and serves as an essential Gα chaperone. Mechanisms by which Ric-8A catalyzes these activities, which are stimulated by Casein Kinase II phosphorylation, are unknown. We report the structure of the nanobody-stabilized complex o...
Article
Because of their small size and their beneficial biochemical and economic properties (size, affinity, specificity, stability, production cost), nanobodies are now increasingly used for routine and more innovative applications in research, biotechnology, and medicine. As they provide access to conformational epitopes in concave and hinge regions, na...
Article
Full-text available
Pentameric ligand-gated ion channels (pLGICs) or Cys-loop receptors are involved in fast synaptic signaling in the nervous system. Allosteric modulators bind to sites that are remote from the neurotransmitter binding site, but modify coupling of ligand binding to channel opening. In this study, we developed nanobodies (single domain antibodies), wh...
Preprint
Full-text available
Ric-8A is a cytosolic Guanine Nucleotide exchange Factor (GEF) that activates heterotrimeric G protein alpha subunits (Gα). Ric-8A is essential to life in multicellular eukaryotes by virtue of its chaperone activity that is required for Gα biogenesis and membrane localization. Ric-8A adopts an armadillo (ARM)/HEAT repeat domain architecture and is...
Article
Full-text available
Prion or PrPSc is the proteinaceous infectious agent causing prion diseases in various mammalian species. Despite decades of research, the structural basis for PrPSc formation and prion infectivity remains elusive. To understand the role of the hydrophobic region in forming infectious prion at the molecular level, we report X-ray crystal structures...
Article
Full-text available
Phospholipids are key components of cellular membranes and are emerging as important functional regulators of different membrane proteins, including pentameric ligand-gated ion channels (pLGICs). Here, we take advantage of the prokaryote channel ELIC (Erwinia ligand-gated ion channel) as a model to understand the determinants of phospholipid intera...
Article
Full-text available
Classically, G-protein-coupled receptors (GPCRs) are thought to activate G protein from the plasma membrane and are subsequently desensitized by β-arrestin (β-arr). However, some GPCRs continue to signal through G protein from internalized compartments, mediated by a GPCR–G protein–β-arr ‘megaplex’. Nevertheless, the molecular architecture of the m...
Article
Full-text available
Anthrax is an ancient and deadly disease caused by the spore-forming bacterial pathogen Bacillus anthracis. At present, anthrax mostly affects wildlife and livestock, although it remains a concern for human public health—primarily for people who handle contaminated animal products and as a bioterrorism threat due to the high resilience of spores, a...
Preprint
Nanobodies (Nbs) are popular and versatile tools for structural biology because they have a compact single immunoglobulin domain organization. Nbs bind their target proteins with high affinities while reducing their conformational heterogeneity, and they stabilize multi-protein complexes. Here we demonstrate that engineered Nbs can also help overco...
Article
Full-text available
Hedgehog (HH) ligands, classical morphogens that pattern embryonic tissues in all animals, are covalently coupled to two lipids—a palmitoyl group at the N terminus and a cholesteroyl group at the C terminus. While the palmitoyl group binds and inactivates Patched 1 (PTCH1), the main receptor for HH ligands, the function of the cholesterol modificat...
Preprint
Full-text available
Pentameric ligand-gated ion channels (pLGICs) belong to a class of ion channels involved in fast synaptic signaling in the central and peripheral nervous systems. Molecules acting as allosteric modulators target binding sites that are remote from the neurotransmitter binding site, but functionally affect coupling of ligand binding to channel openin...
Article
Full-text available
Influenza A viruses are responsible for seasonal epidemics, and pandemics can arise from the transmission of novel zoonotic influenza A viruses to humans1,2. Influenza A viruses contain a segmented negative-sense RNA genome, which is transcribed and replicated by the viral-RNA-dependent RNA polymerase (FluPolA) composed of PB1, PB2 and PA subunits3...
Article
Full-text available
The leading cause of cystic fibrosis (CF) is the deletion of phenylalanine 508 (F508del) in the first nucleotide-binding domain (NBD1) of the cystic fibrosis transmembrane conductance regulator (CFTR). The mutation affects the thermodynamic stability of the domain and the integrity of the interface between NBD1 and the transmembrane domain leading...
Article
Forward-synthetic databases are an efficient way to enumerate chemical space. We explored here whether these databases are good sources of novel protein ligands and how many molecules are obtainable and in which time frame. Based on docking calculations, series of molecules were selected to gain insights into the ligand structure-activity relations...