Characterization of the histone H2A.Z-1 and H2A.Z-2 isoforms in vertebrates
1 Department of Biochemistry and Microbiology and The Center for Biomedical Research, University of Victoria, Petch Building, Victoria, BC, V8W 3P6, Canada
2 California Institute for Quantitative Biosciences, University of California, Berkeley, 642 Stanley Hall, Berkeley, CA, 94720-3220, USA
3 Department of Chemistry, University of Virginia, Charlottesville, VA, 22904, USA
4 The Scripps Research Institute, 130 Scripps Way #1B2, Jupiter, FL, 33458, USA
5 Departamento de Biología Celular y Molecular, Universidade da Coruña, E15071 A Coruña, Spain
6 Department of Oncology, University of Alberta and Cross Cancer Institute, Edmonton, Alberta, T6G 1Z2, Canada
7 Department of Pathology, University of Virginia, Charlottesville, VA, 22904, USA
BMC Biology 2009, 7:86 doi:10.1186/1741-7007-7-86Published: 14 December 2009
Within chromatin, the histone variant H2A.Z plays a role in many diverse nuclear processes including transcription, preventing the spread of heterochromatin and epigenetic transcriptional memory. The molecular mechanisms of how H2A.Z mediates its effects are not entirely understood. However, it is now known that H2A.Z has two protein isoforms in vertebrates, H2A.Z-1 and H2A.Z-2, which are encoded by separate genes and differ by 3 amino acid residues.
We report that H2A.Z-1 and H2A.Z-2 are expressed across a wide range of human tissues, they are both acetylated at lysine residues within the N-terminal region and they exhibit similar, but nonidentical, distributions within chromatin. Our results suggest that H2A.Z-2 preferentially associates with H3 trimethylated at lysine 4 compared to H2A.Z-1. The phylogenetic analysis of the promoter regions of H2A.Z-1 and H2A.Z-2 indicate that they have evolved separately during vertebrate evolution.
Our biochemical, gene expression, and phylogenetic data suggest that the H2A.Z-1 and H2A.Z-2 variants function similarly yet they may have acquired a degree of functional independence.