Small modification, large effect: Diazirine can be installed quickly and simply in the major or minor groove of DNA for efficient photo‐cross‐linking to proteins (see picture). This method should be suitable for mapping out protein–DNA interactions, in particular those that may be sensitive to steric hindrance.

Efficient search for DNA damage embedded in vast expanses of the DNA genome presents one of the greatest challenges to DNA repair enzymes. We report here crystal structures of human 8-oxoguanine (oxoG) DNA glycosylase, hOGG1, that interact with the DNA containing the damaged base oxoG and the normal base G while they are nested in the DNA helical stack. The structures reveal that hOGG1 engages the DNA using different protein-DNA contacts from those observed in the previously determined lesion recognition complex and other hOGG1-DNA complexes. By applying molecular dynamics simulations, we have determined the pathways taken by the lesion and normal bases when extruded from the DNA helix and their associated free energy profiles. These results reveal how the human oxoG DNA glycosylase hOGG1 locates the lesions inside the DNA helix and facilitates their extrusion for repair.

The vast majority of intracellular protein targets are refractory toward small-molecule therapeutic engagement, and additional therapeutic modalities are needed to overcome this deficiency. Here, the identification and characterization of a natural product, WDB002, reveals a therapeutic modality that dramatically expands the currently accepted limits of druggability. WDB002, in complex with the FK506-binding protein (FKBP12), potently and selectively binds the human centrosomal protein 250 (CEP250), resulting in disruption of CEP250 function in cells. The recognition mode is unprecedented in that the targeted domain of CEP250 is a coiled coil and is topologically featureless, embodying both a structural motif and surface topology previously considered on the extreme limits of “undruggability” for an intracellular target. Structural studies reveal extensive protein–WDB002 and protein–protein contacts, with the latter being distinct from those seen in FKBP12 ternary complexes formed by FK506 and rapamycin. Outward-facing structural changes in a bound small molecule can thus reprogram FKBP12 to engage diverse, otherwise “undruggable” targets. The flat-targeting modality demonstrated here has the potential to expand the druggable target range of small-molecule therapeutics. As CEP250 was recently found to be an interaction partner with the Nsp13 protein of the SARS-CoV-2 virus that causes COVID-19 disease, it is possible that WDB002 or an analog may exert useful antiviral activity through its ability to form high-affinity ternary complexes containing CEP250 and FKBP12.

A newly designed 1'-methylenedisulfide deoxyribose probe can efficiently cross-link to DNA cytosine-5-methyltransferases (DNMTs) through the active Cys residue, which provides a new tool to covalently trap DNMT-DNA complexes.

Kleine Veränderung, große Wirkung: Diazirin kann schnell und einfach in der großen und kleinen Furche der DNA verankert werden, um so eine wirksame photoinduzierte Vernetzung der DNA mit Proteinen zu bewirken (siehe Bild). Die Methode sollte zur Kartierung von Protein‐DNA‐Wechselwirkungen geeignet sein, insbesondere solchen, die gegen sterische Hinderungen empfindlich sind.

No abstract

No abstract

No abstract