DNA-SEQUENCES OF GENES ENCODING ACINETOBACTER-CALCOACETICUS PROTOCATECHUATE 3,4-DIOXYGENASE - EVIDENCE INDICATING SHUFFLING OF GENES AND OF DNA-SEQUENCES WITHIN GENES DURING THEIR EVOLUTIONARY DIVERGENCE
DNA-SEQUENCES OF GENES ENCODING ACINETOBACTER-CALCOACETICUS PROTOCATECHUATE 3,4-DIOXYGENASE - EVIDENCE INDICATING SHUFFLING OF GENES AND OF DNA-SEQUENCES WITHIN GENES DURING THEIR EVOLUTIONARY DIVERGENCE
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DOI：
10.1128/jb.172.2.956-966.1990
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发表时间：
1990-02-01
影响因子：
3.2
通讯作者：
ORNSTON, LN
中科院分区：
文献类型：
--
作者：
HARTNETT, C;NEIDLE, EL;ORNSTON, LN
报道了含有 pcaCHG 基因的乙酸钙不动杆菌 DNA 的 2,391 个碱基对 HindIII 限制片段的 DNA 序列。 DNA序列显示，A. calcoacetus pca基因编码原儿茶酸代谢所需的酶，排列在单个转录单元pcaEFDBCHG中，而同源基因在恶臭假单胞菌中排列不同。 pcaG和pcaH基因代表分别编码.alpha的单独阅读框。和.beta。原儿茶酸 3,4-双加氧酶亚基 (EC 1.13.1.3)；以前，使用单一名称 pcaA 来代表编码这种酶的 DNA。 .alpha。和.beta。蛋白质亚基彼此之间以及与来自 A. calcoacetus 和 P. putida 的儿茶酚 1,2-双加氧酶似乎具有共同的祖先。在包含两个组氨酰残基和两个酪氨酰残基的区域中观察到氨基酸序列的显着保守，这些残基似乎连接每个加氧酶内的铁。在比对的加氧酶序列内的一些区域中，DNA序列的保守程度似乎超出了蛋白质水平上的选择可能要求的程度。在其他区域，DNA 序列的分歧似乎是通过将 DNA 序列从一个遗传片段替换为另一个遗传片段而实现的。结果被解释为进化分歧过程中DNA滑动链之间基因转换导致的序列交换的结果；滑移链之间的错配修复可能有助于维持不同基因中的 DNA 序列。
The DNA sequence of a 2,391-base-pair HindIII restriction fragment of Acinetobacter calcoaceticus DNA containing the pcaCHG genes is reported. The DNA sequence reveals that A. calcoaceticus pca genes, encoding enzymes required for protocatechuate metabolism, are arranged in a single transcriptional unit, pcaEFDBCHG, whereas homologous genes are arranged differently in Pseudomonas putida. The pcaG and pcaH genes represent separate reading frames respectively encoding the .alpha. and .beta. subunits of protocatechuate 3,4-dioxygenase (EC 1.13.1.3); previously a single designation, pcaA, had been used to represent DNA encoding this enzyme. The .alpha. and .beta. protein subunits appear to share common ancestry with each other and with catechol 1,2-dioxygenases from A. calcoaceticus and P. putida. Marked conservation of amino acid sequence is observed in a region containing two histidyl residues and two tyrosyl residues that appear to ligate iron within each oxygenase. In some regions within the aligned oxygenase sequences, DNA sequences appear to be conserved at a level beyond the extent that might have been demanded by selection at the level of protein. In other regions, divergence of DNA sequences appears to have been achieved by substitution of DNA sequence from one genetic segment into another. The results are interpreted to be the consequence of sequence exchange by gene conversion between slipped strands of DNA during evolutionary divergence; mismatch repair between slipped strands may contribute to the maintenance of DNA sequence in divergent genes.