Structural highlights
Publication Abstract from PubMedThe creation of restriction enzymes with programmable DNA-binding and -cleavage specificities has long been a goal of modern biology. The recently discovered Type IIL MmeI family of restriction-and-modification (RM) enzymes that possess a shared target recognition domain provides a framework for engineering such new specificities. However, a lack of structural information on Type IIL enzymes has limited the repertoire that can be rationally engineered. We report here a crystal structure of MmeI in complex with its DNA substrate and an S-adenosylmethionine analog (Sinefungin). The structure uncovers for the first time the interactions that underlie MmeI-DNA recognition and methylation (5'-TCCRAC-3'; R = purine) and provides a molecular basis for changing specificity at four of the six base pairs of the recognition sequence (5'-TCCRAC-3'). Surprisingly, the enzyme is resilient to specificity changes at the first position of the recognition sequence (5'-TCCRAC-3'). Collectively, the structure provides a basis for engineering further derivatives of MmeI and delineates which base pairs of the recognition sequence are more amenable to alterations than others. Structure of Type IIL Restriction-Modification Enzyme MmeI in Complex with DNA Has Implications for Engineering New Specificities.,Callahan SJ, Luyten YA, Gupta YK, Wilson GG, Roberts RJ, Morgan RD, Aggarwal AK PLoS Biol. 2016 Apr 15;14(4):e1002442. doi: 10.1371/journal.pbio.1002442., eCollection 2016 Apr. PMID:27082731[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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