This old version of Proteopedia is provided for student assignments while the new version is undergoing repairs. Content and edits done in this old version of Proteopedia after March 1, 2026 will eventually be lost when it is retired in about June of 2026.
Apply for new accounts at the new Proteopedia. Your logins will work in both the old and new versions.
5wvo
From Proteopedia
Crystal structure of DNMT1 RFTS domain in complex with K18/K23 mono-ubiquitylated histone H3
Structural highlights
FunctionRS27A_HUMAN Ubiquitin exists either covalently attached to another protein, or free (unanchored). When covalently bound, it is conjugated to target proteins via an isopeptide bond either as a monomer (monoubiquitin), a polymer linked via different Lys residues of the ubiquitin (polyubiquitin chains) or a linear polymer linked via the initiator Met of the ubiquitin (linear polyubiquitin chains). Polyubiquitin chains, when attached to a target protein, have different functions depending on the Lys residue of the ubiquitin that is linked: Lys-6-linked may be involved in DNA repair; Lys-11-linked is involved in ERAD (endoplasmic reticulum-associated degradation) and in cell-cycle regulation; Lys-29-linked is involved in lysosomal degradation; Lys-33-linked is involved in kinase modification; Lys-48-linked is involved in protein degradation via the proteasome; Lys-63-linked is involved in endocytosis, DNA-damage responses as well as in signaling processes leading to activation of the transcription factor NF-kappa-B. Linear polymer chains formed via attachment by the initiator Met lead to cell signaling. Ubiquitin is usually conjugated to Lys residues of target proteins, however, in rare cases, conjugation to Cys or Ser residues has been observed. When polyubiquitin is free (unanchored-polyubiquitin), it also has distinct roles, such as in activation of protein kinases, and in signaling.[1] [2] Ribosomal protein S27a is a component of the 40S subunit of the ribosome.[3] [4] Publication Abstract from PubMedThe proper location and timing of Dnmt1 activation are essential for DNA methylation maintenance. We demonstrate here that Dnmt1 utilizes two-mono-ubiquitylated histone H3 as a unique ubiquitin mark for its recruitment to and activation at DNA methylation sites. The crystal structure of the replication foci targeting sequence (RFTS) of Dnmt1 in complex with H3-K18Ub/23Ub reveals striking differences to the known ubiquitin-recognition structures. The two ubiquitins are simultaneously bound to the RFTS with a combination of canonical hydrophobic and atypical hydrophilic interactions. The C-lobe of RFTS, together with the K23Ub surface, also recognizes the N-terminal tail of H3. The binding of H3-K18Ub/23Ub results in spatial rearrangement of two lobes in the RFTS, suggesting the opening of its active site. Actually, incubation of Dnmt1 with H3-K18Ub/23Ub increases its catalytic activity in vitro. Our results therefore shed light on the essential role of a unique ubiquitin-binding module in DNA methylation maintenance. Structure of the Dnmt1 Reader Module Complexed with a Unique Two-Mono-Ubiquitin Mark on Histone H3 Reveals the Basis for DNA Methylation Maintenance.,Ishiyama S, Nishiyama A, Saeki Y, Moritsugu K, Morimoto D, Yamaguchi L, Arai N, Matsumura R, Kawakami T, Mishima Y, Hojo H, Shimamura S, Ishikawa F, Tajima S, Tanaka K, Ariyoshi M, Shirakawa M, Ikeguchi M, Kidera A, Suetake I, Arita K, Nakanishi M Mol Cell. 2017 Oct 19;68(2):350-360.e7. doi: 10.1016/j.molcel.2017.09.037. PMID:29053958[5] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
| ||||||||||||||||||||
