@article{BangaloreHeilMehringeretal.2020, author = {Bangalore, Disha M. and Heil, Hannah S. and Mehringer, Christian F. and Hirsch, Lisa and Hemmen, Katharina and Heinze, Katrin G. and Tessmer, Ingrid}, title = {Automated AFM analysis of DNA bending reveals initial lesion sensing strategies of DNA glycosylases}, series = {Scientific Reports}, volume = {10}, journal = {Scientific Reports}, doi = {10.1038/s41598-020-72102-7}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-231338}, year = {2020}, abstract = {Base excision repair is the dominant DNA repair pathway of chemical modifications such as deamination, oxidation, or alkylation of DNA bases, which endanger genome integrity due to their high mutagenic potential. Detection and excision of these base lesions is achieved by DNA glycosylases. To investigate the remarkably high efficiency in target site search and recognition by these enzymes, we applied single molecule atomic force microscopy (AFM) imaging to a range of glycosylases with structurally different target lesions. Using a novel, automated, unbiased, high-throughput analysis approach, we were able to resolve subtly different conformational states of these glycosylases during DNA lesion search. Our results lend support to a model of enhanced lesion search efficiency through initial lesion detection based on altered mechanical properties at lesions. Furthermore, its enhanced sensitivity and easy applicability also to other systems recommend our novel analysis tool for investigations of diverse, fundamental biological interactions.}, language = {en} } @article{LorenzBhattacharyyaFeileretal.2016, author = {Lorenz, Sonja and Bhattacharyya, Moitrayee and Feiler, Christian and Rape, Michael and Kuriyan, John}, title = {Crystal Structure of a Ube2S-Ubiquitin Conjugate}, series = {PLoS ONE}, volume = {11}, journal = {PLoS ONE}, number = {2}, doi = {10.1371/journal.pone.0147550}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-167265}, pages = {e0147550}, year = {2016}, abstract = {Protein ubiquitination occurs through the sequential formation and reorganization of specific protein-protein interfaces. Ubiquitin-conjugating (E2) enzymes, such as Ube2S, catalyze the formation of an isopeptide linkage between the C-terminus of a "donor" ubiquitin and a primary amino group of an "acceptor" ubiquitin molecule. This reaction involves an intermediate, in which the C-terminus of the donor ubiquitin is thioester-bound to the active site cysteine of the E2 and a functionally important interface is formed between the two proteins. A docked model of a Ube2S-donor ubiquitin complex was generated previously, based on chemical shift mapping by NMR, and predicted contacts were validated in functional studies. We now present the crystal structure of a covalent Ube2S-ubiquitin complex. The structure contains an interface between Ube2S and ubiquitin in trans that resembles the earlier model in general terms, but differs in detail. The crystallographic interface is more hydrophobic than the earlier model and is stable in molecular dynamics (MD) simulations. Remarkably, the docked Ube2S-donor complex converges readily to the configuration seen in the crystal structure in 3 out of 8 MD trajectories. Since the crystallographic interface is fully consistent with mutational effects, this indicates that the structure provides an energetically favorable representation of the functionally critical Ube2S-donor interface.}, language = {en} } @phdthesis{Luckner2009, author = {Luckner, Sylvia}, title = {Towards the development of high affinity InhA and KasA inhibitors with activity against drug-resistant strains of Mycobacterium tuberculosis}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-43621}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2009}, abstract = {Mycobacterium tuberculosis is the causative agent of tuberculosis and responsible for more than eight million new infections and about two million deaths each year. Novel chemotherapeutics are urgently needed to treat the emerging threat of multi drug resistant and extensively drug resistant strains. Cell wall biosynthesis is a widely used target for chemotherapeutic intervention in bacterial infections. In mycobacteria, the cell wall is comprised of mycolic acids, very long chain fatty acids that provide protection and allow the bacteria to persist in the human macrophage. The type II fatty acid biosynthesis pathway in Mycobacterium tuberculosis synthesizes fatty acids with a length of up to 56 carbon atoms that are the precursors of the critical mycobacterial cell wall components mycolic acids. KasA, the mycobacterial ß-ketoacyl synthase and InhA, the mycobacterial enoyl reductase, are essential enzymes in the fatty acid biosynthesis pathway and validated drug targets. In this work, KasA was expressed in Mycobacterium smegmatis, purified and co-crystallized in complex with the natural thiolactone antibiotic thiolactomycin (TLM). High-resolution crystal structures of KasA and the C171Q KasA variant, which mimics the acyl enzyme intermediate of the enzyme, were solved in absence and presence of bound TLM. The crystal structures reveal how the inhibitor is coordinated by the enzyme and thus specifically pinpoint towards possible modifications to increase the affinity of the compound and develop potent new drugs against tuberculosis. Comparisons between the TLM bound crystal structures explain the preferential binding of TLM to the acylated form of KasA. Furthermore, long polyethylene glycol molecules are bound to KasA that mimic a fatty acid substrate of approximately 40 carbon atoms length. These structures thus provide the first insights into the molecular mechanism of substrate recognition and reveal how a wax-like substance can be accommodated in a cytosolic environment. InhA was purified and co-crystallized in complex with the slow, tight binding inhibitor 2-(o-tolyloxy)-5-hexylphenol (PT70). Two crystal structures of the ternary InhA-NAD+-PT70 were solved and reveal how the inhibitor is bound to the substrate binding pocket. Both structures display an ordered substrate binding loop and corroborate the hypothesis that slow onset inhibition is coupled to loop ordering. Upon loop ordering, the active site entrance is more restricted and the inhibitor is kept inside more tightly. These studies provide additional information on the mechanistic imperatives for slow onset inhibition of enoyl ACP reductases.}, subject = {Tuberkelbakterium}, language = {en} }