LEAKY TRANSCRIPTION TERMINATION PRODUCES LARGER AND SMALLER THAN GENOME SIZE HEPATITIS-B VIRUS X-GENE TRANSCRIPTS

被引:24
作者
GUO, WT
WANG, J
TAM, G
YEN, TSB
OU, JS
机构
[1] UNIV SO CALIF,DEPT MICROBIOL,2011 ZONAL AVE,LOS ANGELES,CA 90033
[2] UNIV CALIF SAN FRANCISCO,DEPT PATHOL,SAN FRANCISCO,CA 94143
关键词
D O I
10.1016/0042-6822(91)90896-J
中图分类号
Q93 [微生物学];
学科分类号
071005 ; 100705 ;
摘要
The genomic DNA of hepatitis B virus (HBV) is circular and has only one known transcription termination site. The HBV X protein coding sequence is flanked by this transcription termination site at the 3' end and a promoter element at the 5′ end. Transcription initiating from the X promoter and terminating at the termination site would produce a transcript 0.7 kb in length, which we have detected in cell lines that produce HBV particles. Unexpectedly, a 3.9-kb transcript containing two copies of the X gene sequence was also detected in these cell lines. Polymerase chain reaction analysis indicates that this 3.9-kb transcript contains sequences from both upstream and downstream of the termination site. Thus, transcription of this 3.9-kb transcript initiates from the X promoter, reads through the termination site and terminates the second time it encounters the site. Analysis using an SV40-derived vector indicates that the transcription termination site in the HBV genome is also leaky for X gene transcription when a heterologous promoter initiates the transcription. Based on these results, the mechanism of how the transcription termination of HBV mRNA is regulated is discussed. © 1991.
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页码:630 / 636
页数:7
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