SEQUENCE VARIATION IN TRANSCRIPTION FACTOR-IIIA
SEQUENCE VARIATION IN TRANSCRIPTION FACTOR-IIIA
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DOI：
10.1093/nar/18.8.2117
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发表时间：
1990-04-25
影响因子：
14.9
通讯作者：
HANAS, JS
中科院分区：
文献类型：
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作者：
GASKINS, CJ;HANAS, JS
先前的研究表征了非洲爪蟾和林蛙转录因子 IIIA (TFIIIA) 之间的大分子差异 (Gaskins et al., 1989, Nucl. Acids Res. 17, 781-794)。在本研究中，对来自北极爪蟾和美洲牛蛙的 TFIIIA cDNA 进行了克隆和测序，以便从分子角度深入了解 TFIIIA 和 TFIIIA 型锌指的结构、功能和物种变异。 X.borealis 和 R.catesbeiana TFIIIA 分别含有 339 和 335 个氨基酸，比 X.laevis TFIIIA 少 5 和 9 个。 X.borealis TFIIIA与X.laevis TFIIIA表现出84％的序列同源性(55个氨基酸差异)，而R.catesbeiana TFIIIA与X.laevis TFIIIA表现出63％的同源性(128个氨基酸变化)。这种序列变化不是随机的；这些 TFIIIA 的 C 端半部比 N 端半部包含更多的非保守变化。特别是，TFIIIA 的 N 端区域（形成强 DNA 接触的区域）是最保守的，而 C 端尾部（参与转录促进的区域）是最不同的。这些序列的亲水分析揭示了 N 端半部的锌指周期性、C 端半部的极端亲水性以及 R.catesbeiana TFIIIA 的不同 C 端尾部亲水性。尽管这些 TFIIIA 锌指中存在相当大的序列变异，但 Cys/His、Tyr/Phe 和 Leu 残基在 X. laevis 和 X. borealis 之间严格保守。在 X. laevis 和 R. catesbeiana TFIIIA 之间观察到仅 Cys/His 基序的严格保守。总体而言，TFIIIA 中的 Cys/His 锌指比红系转录因子 (Eryf 1) 中的 Cys/Cys 指保守性低得多，并且也比分割基因中的同源框结构域保守性低。集体证据表明 TFIIIA 从包含多达 12 个指状结构域的共同前体进化而来，这些结构域随后以不同的速率进化。
Previous studies characterized macromolecular differences between Xenopus and Rana transcription factor IIIA (TFIIIA) (Gaskins et al., 1989, Nucl. Acids Res. 17, 781-794). In the present study, cDNAs for TFIIIA from Xenopus borealis and Rana catesbeiana (American bullfrog) were cloned and sequenced in order to gain molecular insight into the structure, function, and species variation of TFIIIA and the TFIIIA-type zinc finger. X. borealis and R. catesbeiana TFIIIAs have 339 and 335 amino acids respectively, 5 and 9 fewer than X. laevis TFIIIA. X. borealis TFIIIA exhibited 84% sequence homology (55 amino acid differences) with X. laevis TFIIIA and R. catesbeiana TFIIIA exhibited 63% homology (128 amino acid changes) with X. laevis TFIIIA. This sequence variation is not random; the C-terminal halves of these TFIIIAs contain substantially more non-conservative changes than the N-terminal halves. In particular, the N-terminal region of TFIIIA (that region forming strong DNA contacts) is the most conserved and the C-terminal tail (that region involved in transcription promotion) the most divergent. Hydropathy analyses of these sequences revealed zinc finger periodicity in the N-terminal halves, extreme hydrophilicity in the C-terminal halves, and a different C-terminal tail hydrophathy for R. catesbeiana TFIIIA. Although considerable sequence variation exists in these TFIIIA zinc fingers, the Cys/His, Tyr/Phe and Leu residues are strictly conserved between X. laevis and X. borealis. Strict conservation of only the Cys/His motif is observed between X. laevis and R. catesbeiana TFIIIA. Overall, Cys/His zinc fingers in TFIIIA are much less conserved than Cys/Cys fingers in erythroid transcription factor (Eryf 1) and also less conserved than homeo box domains in segmentation genes. The collective evidence indicates that TFIIIA evolved from a common precursor containing up to 12 finger domains which subsequently evolved at different rates.