Kinetics of re-establishing H3K79 methylation marks in global human chromatin.
We employ a stable isotope strategy wherein both histones and their methylations are labeled in synchronized human cells. This allows us to differentiate between old and new methylations on pre-existing versus newly synthesized histones. The strategy is implemented on K79 methylation in an isoform-specific manner for histones H3.1, H3.2, and H3.3. Although levels of H3.3K79 monomethylation are higher than that of H3.2/H3.1, the rate of establishing the K79 methylation is the same for all three isoforms. Surprisingly, we find that pre-existing "old" histones continue to be K79-monomethylated and -dimethylated at a rate equal to the newly synthesized histones. These observations imply that some degree of positional "scrambling" of K79 methylation occurs through the cell cycle.
Sweet
Steve M M
SMM
From the Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801.
Li
Mingxi
M
From the Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801.
Thomas
Paul M
PM
Proteomics Center of Excellence, Northwestern University, Evanston, Illinois 60208.
Durbin
Kenneth R
KR
From the Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801.
Kelleher
Neil L
NL
From the Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801. Electronic address: n-kelleher@northwestern.edu.
D002453:Cell Cycle / Q000502:physiology*; D002843:Chromatin / Q000378:metabolism*; D006367:HeLa Cells; D006657:Histones / Q000378:metabolism*; D006801:Humans; D008745:Methylation
D002843:Chromatin; D006657:Histones