Characterization of the two H1(zero)-encoding genes from Xenopus laevis.
We have analyzed the promoter and the coding sequences of the two homologous histone H1(zero)-encoding genes from Xenopus laevis, here termed H1(zero)-1 and H1(zero)-2. Both genes encode proteins of 193 amino acids and differ at just 16 amino-acid residues. Putative regulatory sequences identified in the promoter region are the same and are highly conserved. However, significant differences exist in the 5' untranslated regions (UTR) of the transcribed sequences of these two genes, such as several deletions in the 5'-UTR of the H1(zero)-2 gene in comparison with the H1(zero)-1 gene 5'-UTR. The 3'-UTR is a short sequence of about 200 bp which is unexpected compared with the long 3'-UTR of mammalian H1(zero) mRNA, but it is in the same size range as in avian H5 mRNA. Thus, the main differences between these two genes are observed in sequences potentially involved in the regulation of the H1(zero) gene expression such as the 5'-UTR. The two genes are expressed during embryogenesis and in several adult tissues. We discuss these findings in terms of the evolution of histone H1(zero) genes in vertebrates and the appearance of histone H5 in avian species.
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Laboratoire de Biologie Moléculaire du Cycle Cellulaire-INSERM U309, Institut Albert Bonniot, Faculté de Médecine, La Tronche, France.
Triebe
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Peretti
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Doenecke
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Khochbin
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D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002645:Chickens; D003001:Cloning, Molecular; D004625:Embryo, Nonmammalian / Q000378:metabolism; D047108:Embryonic Development; D005796:Genes; D006657:Histones / Q000737:chemistry / Q000235:genetics*; D008969:Molecular Sequence Data; D016133:Polymerase Chain Reaction; D012333:RNA, Messenger / Q000032:analysis; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D012689:Sequence Homology, Nucleic Acid; D014982:Xenopus laevis / Q000235:genetics* / Q000378:metabolism
D006657:Histones; D012333:RNA, Messenger