A5072025848- RNA and protein synthesis mechanisms
- Genetic factors in colorectal cancer
- DNA Repair Mechanisms
- RNA modifications and cancer
- RNA Research and Splicing
- Bacterial Genetics and Biotechnology
- DNA and Nucleic Acid Chemistry
- Advanced biosensing and bioanalysis techniques
- CRISPR and Genetic Engineering
- Genomics and Chromatin Dynamics
- Alzheimer's disease research and treatments
- Cancer Genomics and Diagnostics
- Enzyme Structure and Function
- Prion Diseases and Protein Misfolding
- Cancer-related gene regulation
- RNA Interference and Gene Delivery
- Molecular Biology Techniques and Applications
- Bacteriophages and microbial interactions
- Genomics and Phylogenetic Studies
- Microbial Metabolic Engineering and Bioproduction
- Neuroscience and Neuropharmacology Research
- Epigenetics and DNA Methylation
- Microtubule and mitosis dynamics
- Protein Structure and Dynamics
- Supramolecular Self-Assembly in Materials
Justus-Liebig-Universität Gießen
2015-2024
Giessen School of Theology
2009-2019
University of Massachusetts Chan Medical School
2013
Heinrich Heine University Düsseldorf
2012
KTH Royal Institute of Technology
2012
Wesleyan University
2012
The University of Queensland
2011
Erasmus University Rotterdam
2011
Max Planck Unit for Structural Molecular Biology
1996-2000
Albert Einstein College of Medicine
1998
We have searched for a minimal interaction motif in τ protein that supports the aggregation into Alzheimer-like paired helical filaments. Digestion of repeat domain with different proteases yields GluC-induced fragment comprising 43 residues (termed PHF43), which represents third plus some flanking residues. This self assembles readily thin filaments without appearance, but these are highly competent to nucleate bona fide PHFs from full-length τ. Probing interactions PHF43 overlapping...
The microtubule‐associated protein tau is the main component of paired helical filaments (PHFs) Alzheimer's disease, most common senile dementia. To understand origin tau's abnormal assembly we have studied influence other cytosolic components. Here report that PHF strongly enhanced by RNA. RNA‐induced PHFs dependent on formation intermolecular disulfide bridges involving Cys 322 in third repeat tau, and it includes dimerization as an early intermediate. Three‐repeat constructs polymerize...
Alzheimer's disease is characterized by the progressive deposition of two types fibers in affected brains, amyloid (consisting Aβ peptide, generating plaques) and paired helical filaments (PHFs, made up tau protein, forming neurofibrillary tangles). While principles aggregation are known some detail, investigation PHF assembly has been hampered low efficiency aggregation, requirement high protein concentrations, lack suitable detection methods. Here we report a quantitative assay system that...
Alzheimer’s disease is characterized by two types of fibrous aggregates in the affected brains, amyloid fibers (consisting Aβ-peptide, generating plaques), and paired helical filaments (PHFs; made up tau protein, forming neurofibrillary tangles). Hence, a highly soluble protein that normally stabilizes microtubules, becomes aggregated into insoluble obstruct cytoplasm neurons cause loss microtubule stability. We have developed recently rapid assay for monitoring PHF assembly show here PHFs...
To avoid mutations in the genome, DNA replication is generally followed by mismatch repair (MMR). MMR starts when a MutS homolog recognizes and undergoes an ATP-dependent transformation to elusive sliding clamp state. How this transient state promotes MutL recruitment activation of unclear. Here we present crystal structure MutS/MutL complex using site-specifically crosslinked examine how large conformational changes lead MutL. The captures conformation, where tilting subunits across each...
Abstract How multidomain RNA-binding proteins recognize their specific target sequences, based on a combinatorial code, represents fundamental unsolved question and has not been studied systematically so far. Here we focus prototypical protein, IMP3 (also called IGF2BP3), which contains six domains (RBDs): four KH two RRM domains. We establish an integrative systematic strategy, combining single-domain-resolved SELEX-seq, motif-spacing analyses, in vivo iCLIP, functional validation assays,...
Based on crystal structure analysis of the Serratia nuclease and a sequence alignment six related nucleases, conserved amino acid residues that are located in proximity to previously identified catalytic site residue His89 were selected for mutagenesis study. Five out 12 analyzed turned be particular importance activity enzyme: Arg57, Arg87, His89, Asn119 Glu127. Their replacement by alanine, example, resulted mutant proteins very low activity, < 1% wild-type enzyme. Steady-state kinetic...
MutLα, a heterodimer of MLH1 and PMS2, plays central role in human DNA mismatch repair. It interacts ATP-dependently with the detector MutSα assembles controls further repair enzymes. We tested if interaction MutLα DNA-bound is impaired by cancer-associated mutations MLH1, identified one mutation (Ala128Pro) which abolished as well activity. Further examinations revealed three more residues whose interfered interaction. Homology modelling showed that all clustered small accessible surface...
Missense alterations of the mismatch repair gene MLH1 have been identified in a significant proportion individuals suspected having Lynch syndrome, hereditary syndrome that predisposes for cancer colon and endometrium. The pathogenicity many these alterations, however, is unclear. A number are located C-terminal domain (CTD) MLH1, which responsible constitutive dimerization with PMS2. We analyzed may result pathogenic effects due to interference dimerization. used structural model CTD...
The mutL gene of Neisseria gonorrhoeae has been cloned and the product purified. We have found that homodimeric N. MutL (NgoL) protein displays an endonuclease activity incises covalently closed circular DNA in presence Mn(2+), Mg(2+) or Ca(2+) ions, unlike human MutLalpha which shows only Mn(2+). report present paper C-terminal domain (NgoL-CTD) consisting amino acids 460-658 exhibits Mn(2+)-dependent activity. Sedimentation velocity, sedimentation equilibrium dynamic light scattering...
The ternary complex comprising MutS, MutL, and DNA is a key intermediate in mismatch repair. We used chemical cross-linking fluorescence resonance energy transfer (FRET) to study the interaction between MutS MutL shed light onto structure of this complex. Via cross-linking, we could stabilize dynamic identify structural features events show that mismatch-binding connector domains are proximity N-terminal ATPase domain MutL. DNA- nucleotide-dependent formation be monitored by FRET using...
Mismatch repair (MMR) corrects replication errors such as mismatched bases and loops in DNA. The evolutionarily conserved dimeric MMR protein MutS recognizes mismatches by stacking a phenylalanine of one subunit against base the pair. In all crystal structures G:T mismatch-bound MutS, is stacked thymine. To explore whether these reflect directional mismatch recognition we monitored orientation Escherichia coli binding to FRET anisotropy with steady state, pre-steady state single-molecule...
The process of DNA mismatch repair is initiated when MutS recognizes mismatched bases and starts the cascade. Escherichia coli protein exists in an equilibrium between dimers tetramers, which has compromised biophysical analysis. To uncouple these states, we have generated stable respectively. These proteins allowed kinetic analysis recognition structural full-length by X-ray crystallography small angle scattering. Our data reveal that tetramerization domains are flexible with respect to...
DNA mismatch repair (MMR) maintains genome stability through of replication errors. In Escherichia coli, initiation MMR involves recognition the by MutS, recruitment MutL, activation endonuclease MutH and strand incision at a hemimethylated GATC site. Here, we studied mechanism communication that couples to daughter incision. We investigated effect catalytically-deficient Cas9 as well stalled RNA polymerase roadblocks placed on in between site ensemble single molecule nanomanipulation...
By sequence alignment of the extracellular Serratia marcescens nuclease with three related nucleases we have identified seven charged amino acid residues which are conserved in all four sequences. Six these together other partially His or Asp were changed to alanine by site-directed PCR-mediated mutagenesis using a variant gene coding signal peptide was replaced for an N-terminal affinity tag [Met(His)6GlySer]. Four mutant proteins showed almost no reduction activity but five displayed 10-...
Here, we report that <i>Sau</i>3AI, an unusually large type II restriction enzyme with sequence homology to the mismatch repair protein MutH, is a monomeric as shown by gel filtration and ultracentrifugation. Structural similarities in N- C-terminal halves of suggest <i>Sau</i>3AI pseudo-dimer, <i>i.e.</i> polypeptide two similar domains. Since displays nonlinear dependence cleavage activity on concentration strong preference for substrates recognition sites over those only one, it likely...