The internal head protein gp16 controls DNA ejection from the bacteriophage T7 virion
The internal head protein gp16 controls DNA ejection from the bacteriophage T7 virion
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DOI：
10.1006/jmbi.2000.3940
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发表时间：
2000-08-04
影响因子：
5.6
通讯作者：
Molineux, IJ
中科院分区：
文献类型：
--
作者：
Struthers-Schlinke, JS;Robins, WP;Molineux, IJ
野生型T7病毒体通过独立于转录的过程将约850 bp的40 kb基因组喷射到细菌细胞中。其余基因组的内在化通常需要转录。超出领先的850 bp以外的转录独立的DNA易位的抑制不是绝对的感染DNA分子的20％完全穿透了四个小时的感染后的细胞质。含有改变基因16蛋白的突变病毒可以防止块与转录独立的DNA易位或从阻塞位点迅速释放的块，并允许整个噬菌体DNA分子以每秒约75 bp的恒定速率进入细胞。该速率可能与从野生型病毒体中弹出到细胞中的主要850 bp相同。所有突变均落入4 kb基因16的380 bp之内的两个簇，这表明GP16的127个残基段控制了噬菌体颗粒的DNA射精。我们认为，这一段GP16充当夹具，以防止独立于转录的DNA易位。 （c）2000学术出版社。
A wild-type T7 virion ejects about 850 bp of the 40 kb genome into the bacterial cell by a transcription-independent process. Internalization of the remainder of the genome normally requires transcription. Inhibition of transcription-independent DNA translocation beyond the leading 850 bp is not absolute but the time taken by a population of phage genomes in overcoming the block averages about 20 minutes at 30 degrees C. There are additional blocks to transcription-independent translocation and less than 20 % of infecting DNA molecules completely penetrate the cell cytoplasm after four hours of infection. Mutant virions containing an altered gene 16 protein either prevent the blocks to transcription-independent DNA translocation or effect rapid release from blocking sites and allow the entire phage DNA molecule to enter the cell at a constant rate of about 75 bp per second. This rate is Likely the same at which the leading 850 bp is ejected into the cell from a wild-type virion. All mutations fall into two clusters contained within 380 bp of the 4 kb gene 16, suggesting that a 127 residue segment of gp16 controls DNA ejection from the phage particle. We suggest that this segment of gp16 acts as a clamp to prevent transcription-independent DNA translocation. (C) 2000 Academic Press.