Nakamuta M, Tsai A, Chan L, Davidson N O, Teng B B
Institute of Molecular Medicine, University of Texas-Houston, Houston, Texas, 77030, USA.
Biochem Biophys Res Commun. 1999 Jan 27;254(3):744-50. doi: 10.1006/bbrc.1998.9963.
Mammalian intestinal apolipoprotein B (apoB) mRNA edits codon 2153 from CAA in apoB100 mRNA to a stop codon (UAA) in apoB48 mRNA. By contrast, chicken intestinal apoB mRNA contains a CAA codon at the corresponding site, but is not edited. Chicken enterocyte S100 extracts fail to edit mammalian apoB RNA, but contain factor(s) which enhance the mammalian enterocytes editing activity. By converting the chicken apoB mooring sequences to the conserved mammalian sequences, the study confirmed that this 11-nucleotide stretch was necessary and sufficient for minimal RNA editing. Using rat and chicken apoB chimeric constructs, the study revealed that mammalian apoB sequences were required for editing enhancement. In concert with the 29-nucleotide conserved cassette, the 5' rat apoB element (nucleotides 6615-6629) increased editing at C-6666, and was necessary for editing enhancement of chicken enterocyte S100 extracts. Similarly, the 3' rat apoB element (nucleotides 6726-6752) was required for editing enhancement of chicken enterocyte S100 extracts, but to a lesser extent in efficiency, compared to the 5' region. In conclusion, this study identified the sequences required for editing enhancement activity from chicken enterocyte S100 extracts.
哺乳动物肠道载脂蛋白B（apoB）信使核糖核酸（mRNA）将apoB100 mRNA中的密码子2153由CAA编辑为apoB48 mRNA中的终止密码子（UAA）。相比之下，鸡肠道apoB mRNA在相应位点含有CAA密码子，但未被编辑。鸡肠上皮细胞S100提取物无法编辑哺乳动物apoB核糖核酸（RNA），但含有增强哺乳动物肠上皮细胞编辑活性的因子。通过将鸡apoB系留序列转换为保守的哺乳动物序列，该研究证实这段11个核苷酸的片段对于最低限度的RNA编辑是必要且充分的。利用大鼠和鸡apoB嵌合构建体，该研究揭示编辑增强需要哺乳动物apoB序列。与29个核苷酸的保守盒协同作用，5'端大鼠apoB元件（核苷酸6615 - 6629）增加了C - 6666处的编辑，并且是增强鸡肠上皮细胞S100提取物编辑所必需的。同样，3'端大鼠apoB元件（核苷酸6726 - 6752）是增强鸡肠上皮细胞S100提取物编辑所必需的，但与5'区域相比，效率较低。总之，本研究确定了增强鸡肠上皮细胞S100提取物编辑活性所需的序列。
