Abstract
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.
Publication types
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Research Support, N.I.H., Extramural
MeSH terms
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Animals
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Cell Cycle Proteins / chemistry
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Cell Cycle Proteins / genetics
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Cell Cycle Proteins / metabolism*
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Chromatin / metabolism*
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Chromatin Assembly and Disassembly*
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Cloning, Molecular
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DNA / metabolism
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Dogs
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Guanine Nucleotide Exchange Factors / chemistry
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Guanine Nucleotide Exchange Factors / genetics
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Guanine Nucleotide Exchange Factors / metabolism*
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HeLa Cells
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Histones / metabolism
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Humans
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Kinetics
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Luminescent Proteins / genetics
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Luminescent Proteins / metabolism
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Methionine / chemistry
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Methylation
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Mitosis / physiology*
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Mutation
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Nuclear Proteins / chemistry
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Nuclear Proteins / genetics
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Nuclear Proteins / metabolism*
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Proline / metabolism
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Protein Binding
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Protein Conformation
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Protein Methyltransferases / metabolism*
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Protein Processing, Post-Translational*
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Recombinant Fusion Proteins / metabolism
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Serine / metabolism
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ran GTP-Binding Protein / metabolism
Substances
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Cell Cycle Proteins
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Chromatin
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Guanine Nucleotide Exchange Factors
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Histones
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Luminescent Proteins
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Nuclear Proteins
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RCC1 protein, human
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Recombinant Fusion Proteins
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Serine
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DNA
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Proline
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Methionine
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Protein Methyltransferases
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ran GTP-Binding Protein