The nonessential H2A N-terminal tail can function as an essential charge patch on the H2A.Z variant N-terminal tail.
Tetrahymena thermophila cells contain three forms of H2A: major H2A.1 and H2A.2, which make up approximately 80% of total H2A, and a conserved variant, H2A.Z. We showed previously that acetylation of H2A.Z was essential (Q. Ren and M. A. Gorovsky, Mol. Cell 7:1329-1335, 2001). Here we used in vitro mutagenesis of lysine residues, coupled with gene replacement, to identify the sites of acetylation of the N-terminal tail of the major H2A and to analyze its function in vivo. Tetrahymena cells survived with all five acetylatable lysines replaced by arginines plus a mutation that abolished acetylation of the N-terminal serine normally found in the wild-type protein. Thus, neither posttranslational nor cotranslational acetylation of major H2A is essential. Surprisingly, the nonacetylatable N-terminal tail of the major H2A was able to replace the essential function of the acetylation of the H2A.Z N-terminal tail. Tail-swapping experiments between H2A.1 and H2A.Z revealed that the nonessential acetylation of the major H2A N-terminal tail can be made to function as an essential charge patch in place of the H2A.Z N-terminal tail and that while the pattern of acetylation of an H2A N-terminal tail is determined by the tail sequence, the effects of acetylation on viability are determined by properties of the H2A core and not those of the N-terminal tail itself.
Ren
Qinghu
Q
Department of Biology, University of Rochester, Rochester, New York 14627, USA.
Gorovsky
Martin A
MA
D000107:Acetylation; D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D004563:Electrochemistry; D017125:Genes, Protozoan; D014644:Genetic Variation; D006657:Histones / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D008239:Lysine / Q000737:chemistry; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D009154:Mutation; D011499:Protein Processing, Post-Translational; D015800:Protozoan Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D016808:Tetrahymena thermophila / Q000235:genetics / Q000378:metabolism*
D006657:Histones; D015800:Protozoan Proteins; D011993:Recombinant Fusion Proteins; D008239:Lysine