Woudt L P, Pastink A, Kempers-Veenstra A E, Jansen A E, Mager W H, Planta R J
Nucleic Acids Res. 1983 Aug 25;11(16):5347-60. doi: 10.1093/nar/11.16.5347.
Sequences coding for histone H3 and H4 of Neurospora crassa could be identified in genomic digests with the use of the corresponding genes from sea urchin and X. laevis as hybridization probes. A 2.6 kb HindIII-generated N. crassa DNA fragment, showing homology with the heterologous histone H3-gene probes was cloned in a charon 21A vector. Using DNA from this clone as a homologous hybridization probe a 6.9 kb SalI-generated DNA fragment was isolated which in addition to the histone H3-gene also contains the gene coding for histone H4. Several lines of evidence demonstrate the presence of only a single histone H3- as well as a single histone H4-gene in N. crassa. The two genes are physically linked on the genome. DNA sequencing of the N. crassa histone H3- and H4-genes confirmed their identity and, in addition, revealed the presence of one short intron (67 bp) within the coding sequence of the H3-gene and even two introns (68 and 69 bp) within the H4-gene. The amino acid sequences of the N. crassa histones H3 and H4, as deduced from the DNA sequences, and those of the corresponding yeast histones differ only at a few positions. Much larger sequence differences, however, are observed at the DNA level, reflecting a diverging codon usage in the two lower eukaryotes.
利用海胆和非洲爪蟾的相应基因作为杂交探针，可在粗糙脉孢菌基因组消化产物中鉴定出编码组蛋白H3和H4的序列。一个由HindIII酶切产生的2.6 kb粗糙脉孢菌DNA片段，与异源组蛋白H3基因探针显示出同源性，被克隆到Charon 21A载体中。以该克隆的DNA作为同源杂交探针，分离出一个由SalI酶切产生的6.9 kb DNA片段，该片段除了含有组蛋白H3基因外，还包含编码组蛋白H4的基因。几条证据表明粗糙脉孢菌中仅存在单个组蛋白H3基因以及单个组蛋白H4基因。这两个基因在基因组上物理相连。粗糙脉孢菌组蛋白H3和H4基因的DNA测序证实了它们的一致性，此外，还揭示出H3基因编码序列中有一个短内含子（67 bp），而H4基因中甚至有两个内含子（68和69 bp）。从DNA序列推导的粗糙脉孢菌组蛋白H3和H4的氨基酸序列，与相应酵母组蛋白的氨基酸序列仅在少数位置存在差异。然而，在DNA水平上观察到的序列差异要大得多，这反映了这两种低等真核生物中密码子使用的差异。
