Roberts S B, Emmons S W, Childs G
Department of Genetics, Albert Einstein College of Medicine, Bronx, NY 10461.
J Mol Biol. 1989 Apr 20;206(4):567-77. doi: 10.1016/0022-2836(89)90566-4.
We have determined the nucleotide sequence of core histone genes and flanking regions from two of approximately 11 different genomic histone clusters of the nematode Caenorhabditis elegans. Four histone genes from one cluster (H3, H4, H2B, H2A) and two histone genes from another (H4 and H2A) were analyzed. The predicted amino acid sequences of the two H4 and H2A proteins from the two clusters are identical, whereas the nucleotide sequences of the genes have diverged 9% (H2A) and 12% (H4). Flanking sequences, which are mostly not similar, were compared to identify putative regulatory elements. A conserved sequence of 34 base-pairs is present 19 to 42 nucleotides 3' of the termination codon of all the genes. Within the conserved sequence is a 16-base dyad sequence homologous to the one typically found at the 3' end of histone genes from higher eukaryotes. The C. elegans core histone genes are organized as divergently transcribed pairs of H3-H4 and H2A-H2B and contain 5' conserved sequence elements in the shared spacer regions. One of the sequence elements, 5' CTCCNCCTNCCCACCNCANA 3', is located immediately upstream from the canonical TATA homology of each gene. Another sequence element, 5' CTGCGGGGACACATNT 3', is present in the spacer of each heterotypic pair. These two 5' conserved sequences are not present in the promoter region of histone genes from other organisms, where 5' conserved sequences are usually different for each histone class. They are also not found in non-histone genes of C. elegans. These putative regulatory sequences of C. elegans core histone genes are similar to the regulatory elements of both higher and lower eukaryotes. The coding regions of the genes and the 3' regulatory sequences are similar to those of higher eukaryotes, whereas the presence of common 5' sequence elements upstream from genes of different histone classes is similar to histone promoter elements in yeast.
我们已经确定了线虫秀丽隐杆线虫大约11个不同基因组组蛋白簇中的两个簇的核心组蛋白基因及其侧翼区域的核苷酸序列。对一个簇中的四个组蛋白基因（H3、H4、H2B、H2A）和另一个簇中的两个组蛋白基因（H4和H2A）进行了分析。来自两个簇的两个H4和H2A蛋白的预测氨基酸序列是相同的，而基因的核苷酸序列已经有了9%（H2A）和12%（H4）的分歧。对大多不相似的侧翼序列进行了比较，以确定推定的调控元件。在所有基因终止密码子下游19至42个核苷酸处存在一个34个碱基对的保守序列。在保守序列内是一个16碱基的二元序列，与在高等真核生物组蛋白基因3'端通常发现的序列同源。秀丽隐杆线虫的核心组蛋白基因被组织成H3-H4和H2A-H2B的反向转录对，并在共享间隔区含有5'保守序列元件。其中一个序列元件5' CTCCNCCTNCCCACCNCANA 3'位于每个基因典型TATA同源序列的紧邻上游。另一个序列元件5' CTGCGGGGACACATNT 3'存在于每个异型对的间隔区。这两个5'保守序列不存在于其他生物的组蛋白基因启动子区域，在其他生物中，每个组蛋白类别的5'保守序列通常是不同的。它们也未在秀丽隐杆线虫的非组蛋白基因中发现。秀丽隐杆线虫核心组蛋白基因的这些推定调控序列与高等和低等真核生物的调控元件相似。基因的编码区和3'调控序列与高等真核生物的相似，而不同组蛋白类基因上游常见5'序列元件的存在与酵母中的组蛋白启动子元件相似。
