4LVL:
reference: Structural basis of a histidine-DNA nicking/joining mechanism for gene transfer and promiscuous spread of antibiotic resistance., Pluta R, Boer DR, Lorenzo-Diaz F, Russi S, Gomez H, Fernandez-Lopez C, Perez-Luque R, Orozco M, Espinosa M, Coll M, Proc Natl Acad Sci U S A. 2017 Aug 8;114(32):E6526-E6535. doi:, 10.1073/pnas.1702971114. Epub 2017 Jul 24. PMID: 28739894

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