5np7
CryoEM structure of Human Rad51 on single-stranded DNA to 4.2A resolution.
Structural highlights
DiseaseRAD51_HUMAN Defects in RAD51 are a cause of susceptibility to breast cancer (BC) [MIM:114480. A common malignancy originating from breast epithelial tissue. Breast neoplasms can be distinguished by their histologic pattern. Invasive ductal carcinoma is by far the most common type. Breast cancer is etiologically and genetically heterogeneous. Important genetic factors have been indicated by familial occurrence and bilateral involvement. Mutations at more than one locus can be involved in different families or even in the same case.[1] Defects in RAD51 are the cause of mirror movements type 2 (MRMV2) [MIM:614508. A disorder characterized by contralateral involuntary movements that mirror voluntary ones. While mirror movements are occasionally found in young children, persistence beyond the age of 10 is abnormal. Mirror movements occur more commonly in the upper extremities.[2] FunctionRAD51_HUMAN Participates in a common DNA damage response pathway associated with the activation of homologous recombination and double-strand break repair. Binds to single and double stranded DNA and exhibits DNA-dependent ATPase activity. Underwinds duplex DNA and forms helical nucleoprotein filaments. Plays a role in regulating mitochondrial DNA copy number under conditions of oxidative stress in the presence of RAD51C and XRCC3.[3] [4] [5] Publication Abstract from PubMedHomologous DNA recombination (HR) by the RAD51 recombinase enables error-free DNA break repair. To execute HR, RAD51 first forms a presynaptic filament on single-stranded (ss) DNA, which catalyses pairing with homologous double-stranded (ds) DNA. Here, we report a structure for the presynaptic human RAD51 filament at 3.5-5.0A resolution using electron cryo-microscopy. RAD51 encases ssDNA in a helical filament of 103A pitch, comprising 6.4 protomers per turn, with a rise of 16.1A and a twist of 56.2 degrees . Inter-protomer distance correlates with rotation of an alpha-helical region in the core catalytic domain that is juxtaposed to ssDNA, suggesting how the RAD51-DNA interaction modulates protomer spacing and filament pitch. We map Fanconi anaemia-like disease-associated RAD51 mutations, clarifying potential phenotypes. We predict binding sites on the presynaptic filament for two modules present in each BRC repeat of the BRCA2 tumour suppressor, a critical HR mediator. Structural modelling suggests that changes in filament pitch mask or expose one binding site with filament-inhibitory potential, rationalizing the paradoxical ability of the BRC repeats to either stabilize or inhibit filament formation at different steps during HR. Collectively, our findings provide fresh insight into the structural mechanism of HR and its dysregulation in human disease. High-resolution structure of the presynaptic RAD51 filament on single-stranded DNA by electron cryo-microscopy.,Short JM, Liu Y, Chen S, Soni N, Madhusudhan MS, Shivji MK, Venkitaraman AR Nucleic Acids Res. 2016 Sep 5. pii: gkw783. PMID:27596592[6] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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