9bs4

DNA Ligase 1 E346A/E592A double mutant with 5'-rG:C

spinqualitylabelsall models 9bs4, resolution 2.40Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 9bs4 is a 8 chain structure with sequence from Homo sapiens and Synthetic construct. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Method: X-ray diffraction, Resolution 2.4Å Ligands: AMP Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function DNLI1_HUMAN DNA ligase that seals nicks in double-stranded DNA during DNA replication, DNA recombination and DNA repair. Publication Abstract from PubMed Ribonucleotides in DNA cause several types of genome instability and can be removed by ribonucleotide excision repair (RER) that is finalized by DNA ligase 1 (LIG1). However, the mechanism by which LIG1 discriminates the RER intermediate containing a 5'-RNA-DNA lesion generated by RNase H2-mediated cleavage of ribonucleotides at atomic resolution remains unknown. Here, we determine X-ray structures of LIG1/5'-rG:C at the initial step of ligation where AMP is bound to the active site of the ligase and uncover a large conformational change downstream the nick resulting in a shift at Arg(R)871 residue in the Adenylation domain of the ligase. Furthermore, we demonstrate a diminished ligation of the nick DNA substrate with a 5'-ribonucleotide in comparison to an efficient end joining of the nick substrate with a 3'-ribonucleotide by LIG1. Finally, our results demonstrate that mutations at the active site residues of the ligase and LIG1 disease-associated variants significantly impact the ligation efficiency of RNA-DNA heteroduplexes harboring "wrong" sugar at 3'- or 5'-end of nick. Collectively, our findings provide a novel atomic insight into proficient sugar discrimination by LIG1 during the processing of the most abundant form of DNA damage in cells, genomic ribonucleotides, during the initial step of the RER pathway. Structures of LIG1 uncover the mechanism of sugar discrimination against 5'-RNA-DNA junctions during ribonucleotide excision repair.,Balu KE, Tang Q, Almohdar D, Ratcliffe J, Kalaycioglu M, Caglayan M J Biol Chem. 2024 Aug 17;300(9):107688. doi: 10.1016/j.jbc.2024.107688. PMID:39159820 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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