Analysis of histones in xenopus Laevis II. mass spectrometry reveals an index of cell type-specific modifications on H3 and H4

Joshua J. Nicklay, David Shechter, Raghu K. Chitta, Benjamin A. Garcia, Jeffrey Shabanowitz, C. David Allis, Donald F. Hunt

Research output: Contribution to journalArticlepeer-review

41 Scopus citations


Epigenetic information is hypothesized to be encoded in his-tone variants and post-translational modifications. Varied cell-and locus-specific combinations of these epigenetic marks are likely contributors to regulation of chromatin-templated transactions, including transcription, replication, recombination, and repair. Therefore, the relative abundance of histone modifications in a given cell type is a potential index of cell fate and specificity. Here, we utilize mass spectrometry techniques to characterize the relative abundance index of cell type-specific modifications on histones H3 and H4 in distinct cell types from the frog Xenopus laevis, including the sperm, the stored prede-position histones in the egg, the early embryo equivalent pronu-clei, cultured somatic cells, and erythrocytes. We used collision-ally associated dissociation to identify the modifications present on histone H3 in a variety of cell types, resolving 26 distinctly modified H3 peptides. We employed the electron transfer dissociation fragmentation technique in a "middle-down" approach on the H4 N-terminal tail to explore the overlap of post-translational modifications. We observed 66 discrete iso-forms of the H4 1-23 fragment in four different cell types. Isolation of the stored, predeposition histone H4 from the frog egg also revealed a more varied pattern of modifications than the previously known diacetylation on Lys5 and Lys12. The developmental transitions of modifications on H3 and H4 were strikingly varied, implying a strong correlation of the histone code with cell type and fate. Our results are consistent with a histone code index for each cell type and uncover potential cross-talk between modifications on a single tail.

Original languageEnglish
Pages (from-to)1075-1085
Number of pages11
JournalJournal of Biological Chemistry
Issue number2
StatePublished - Jan 9 2009


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