N-terminal alpha-methylation of RCC1 is necessary for stable chromatin association and normal mitosis.
Regulator of chromatin condensation 1 (RCC1) is the only known guanine nucleotide-exchange factor for the Ran GTPase and has pivotal roles in nucleo-cytoplasmic transport, mitosis, and nuclear-envelope assembly. RCC1 associates dynamically with chromatin through binding to histones H2A and/or H2B in a Ran-regulated manner. Here, we report that, unexpectedly, the amino-terminal serine or proline residue of RCC1 is uniquely methylated on its alpha-amino group. Methylation requires removal of the initiating methionine, and the presence of proline and lysine at positions 3 and 4, respectively. Methylation-defective mutants of RCC1 bind less effectively than wild-type protein to chromatin during mitosis, which causes spindle-pole defects. We propose a bimodal attachment mechanism for RCC1 in which the tail promotes stable RCC1 association with chromatin through DNA binding in an alpha-N-methylation-dependent manner. These data provide the first known function for N-terminal protein methylation.
Chen
Ting
T
Department of Microbiology, Center for Cell Signaling, University of Virginia School of Medicine University of Virginia, Charlottesville, VA 22908-0577, USA.
Muratore
Tara L
TL
Schaner-Tooley
Christine E
CE
Shabanowitz
Jeffrey
J
Hunt
Donald F
DF
Macara
Ian G
IG
D000818:Animals; D018797:Cell Cycle Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D002843:Chromatin / Q000378:metabolism*; D042002:Chromatin Assembly and Disassembly; D003001:Cloning, Molecular; D004247:DNA / Q000378:metabolism; D004285:Dogs; D020662:Guanine Nucleotide Exchange Factors / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D006367:HeLa Cells; D006657:Histones / Q000378:metabolism; D006801:Humans; D007700:Kinetics; D008164:Luminescent Proteins / Q000235:genetics / Q000378:metabolism; D008715:Methionine / Q000737:chemistry; D008745:Methylation; D008938:Mitosis / Q000502:physiology*; D009154:Mutation; D009687:Nuclear Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D011392:Proline / Q000378:metabolism; D011485:Protein Binding; D011487:Protein Conformation; D011496:Protein Methyltransferases / Q000378:metabolism*; D011499:Protein Processing, Post-Translational; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D012694:Serine / Q000378:metabolism; D020931:ran GTP-Binding Protein / Q000378:metabolism
D018797:Cell Cycle Proteins; D002843:Chromatin; D020662:Guanine Nucleotide Exchange Factors; D006657:Histones; D008164:Luminescent Proteins; D009687:Nuclear Proteins; C062521:RCC1 protein, human; D011993:Recombinant Fusion Proteins; D012694:Serine; D004247:DNA; D011392:Proline; D008715:Methionine; D011496:Protein Methyltransferases; D020931:ran GTP-Binding Protein