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Publication Abstract from PubMed

Type I restriction-modification enzymes are oligomeric proteins composed of methylation (M), DNA sequence-recognition (S), and restriction (R) subunits. The different bipartite DNA sequences of 2-4 consecutive bases are recognized by two discerned target recognition domains (TRDs) located at the two-helix bundle of the two conserved regions (CRs). Two M-subunits and a single S-subunit form an oligomeric protein that functions as a methyltransferase (M(2)S(1) MTase). Here, we present the crystal structure of the intact MTase from Vibrio vulnificus YJ016 in complex with the DNA-mimicking Ocr protein and the S-adenosyl-L-homocysteine (SAH). This MTase includes the M-domain with a helix tail (M-tail helix) and the S(1/2)-domain of a TRD and a CR alpha-helix. The Ocr binds to the cleft of the TRD surface and SAH is located in the pocket within the M-domain. The solution- and negative-staining electron microscopy-based reconstructed (M(1)S(1/2))(2) structure reveals a symmetric (S(1/2))(2) assembly using two CR-helices and two M-tail helices as a pivot, which is plausible for recognizing two DNA regions of same sequence. The conformational flexibility of the minimal M(1)S(1/2) MTase dimer indicates a particular state resembling the structure of M(2)S(1) MTases.

Structural features of a minimal intact methyltransferase of a type I restriction-modification system.,Seo PW, Hofmann A, Kim JH, Hwangbo SA, Kim JH, Kim JW, Huynh TYL, Choy HE, Kim SJ, Lee J, Lee JO, Jin KS, Park SY, Kim JS Int J Biol Macromol. 2022 May 31;208:381-389. doi: , 10.1016/j.ijbiomac.2022.03.115. Epub 2022 Mar 23. PMID:35337914^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.