Organization of the Chicken Histone Genes in a Major Gene Cluster and Generation of an Almost Complete Set of the Core Histone Protein Sequences

Abstract

We present a detailed picture of the disposition of the histone genes in the chicken genome and an almost complete set of the core histone protein sequences. Thirty-nine histone genes, six H1, nine H2A, eight H2B, eight H3 and eight H4, were located within a histone gene cluster of 110 kb, which was covered by five cosmid clones and two lambda clones. Results of our sequence analyses, together with those reported previously, generated a set of the core histone amino acid sequences as follows: three H2A variants, four H2B variants, two H3 variants and an H4 protein.

A single copy of linker H1 genes is enough for proliferation of the DT40 chicken B cell line, and linker H1 variants participate in regulation of gene expression

“…As expected (see Fig. 3A-b,c), after integration of the pD02H1/hyg construct into the 02H1 locus in one of the analysed clones, probe 3 newly hybridized to both the HindIII/BamHI fragment of 12.0 kb and the HindIII fragment of 15.5 kb, in addition to the endogenous fragments of 9.5 kb and 13.0 kb (Takami et al 1996). (B) Schematic diagram of the histone gene cluster in the D57kb mutant (Takami et al 1997).…”

“…From the D57kb mutant devoid of four of the six H1 genes, besides the 17 H2A, H2B, H3 and H4 genes, included in the Ϸ 57 kb segment of the gene cluster of 110 kb carrying 39 of the 44 histone genes (Takami et al 1996(Takami et al , 1997) (see Fig. 1A), we first generated the homozygous DT40 mutant (D10/12H1), which further lacks two copies of one of the two residual H1 genes .10H1, using the pD.10H1/hisD and pD.10H1/Eco-gpt constructs (Fig.…”

“…Furthermore, only a unique H1 variant, 02H1, is sufficient for cell proliferation, since the six chicken H1 genes, respectively, encode six variants (H1 L, H1R .10H1, 01H1, 02H1 and 03H1), which are considerably distinct in their amino acid sequences, especially in their N and C-terminal regions (Coles et al 1987;Takami et al 1996), and both the D10/12H1 and D11/12H1 mutants lack the five other H1 variants completely. Either of the five residual H1 variants alone should also be enough for cell proliferation, because we recently obtained similar results for the DT40 mutant that contains only a single .10H1 allele of the 12 H1 gene copies (data not shown).…”

“…The previously constructed D57kb mutant lacks four of the six H1 genes, in addition to six of the nine H2A genes, four of the eight H2B genes, four of the 11 H3 genes, and three of the nine H4 genes, all of which are located in the Ϸ 57 kb segment of the gene cluster of 110 kb (Takami et al 1996(Takami et al , 1997) (see Fig. 1A).…”

“…As sources of chicken genomic DNAs, we first prepared a HindIII/HindIII fragment of 2.1 kb carrying .10H1, and an EcoRI/BamHI fragment of 5.7 kb carrying 02H1 from l#2-7 and pCos#6, respectively (Takami et al 1996). The two fragments are located on the left and right of the segment of 53 kb carrying 18 of the 39 genes included in the histone gene cluster of 110 kb (see Fig.…”