Two Mms2 residues cooperatively interact with ubiquitin and are critical for Lys63 polyubiquitination in vitro and in vivo.
Recent structural analyses support a model whereby Mms2 interacts with and orientates Ub to promote Ubc13-mediated Lys63 chain formation. However, residues of the hMms2-Ub interface have not been addressed. We found two hMms2 residues to be critical for binding and polyUb conjugation. Surprisingly, while each single mutation reduces the binding affinity, the double mutation causes significant reduction of Ub binding and abolishes polyUb chain formation. Furthermore, the corresponding yeast mms2 double mutant exhibited an additive phenotype that caused a complete loss of MMS2 function. Taken together, this study identifies key residues of the Mms2-Ub interface and provides direct experimental evidence that Mms2 physical association with Ub is correlated with its ability to promote Lys63-linked Ub chain assembly.
Pastushok
Landon
L
Department of Microbiology and Immunology, University of Saskatchewan, Saskatoon, SK, Canada.
Spyracopoulos
Leo
L
Xiao
Wei
W
D000595:Amino Acid Sequence; D000818:Animals; D004247:DNA / Q000235:genetics; D004260:DNA Repair / Q000235:genetics; D004261:DNA Replication / Q000235:genetics; D019281:Dimerization; D008025:Ligases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D008239:Lysine / Q000235:genetics / Q000378:metabolism; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009154:Mutation / Q000235:genetics; D020836:Protein Structure, Quaternary; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D025801:Ubiquitin / Q000378:metabolism*; D044763:Ubiquitin-Conjugating Enzymes; D054875:Ubiquitination
D025801:Ubiquitin; D004247:DNA; C114715:UBE2V2 protein, human; D044763:Ubiquitin-Conjugating Enzymes; D008025:Ligases; D008239:Lysine