CONDITIONAL LETHAL MUTATION IN AN ESCHERICHIA-COLI STRAIN WITH A LONGER CHEMICAL LIFETIME OF MESSENGER-RNA
CONDITIONAL LETHAL MUTATION IN AN ESCHERICHIA-COLI STRAIN WITH A LONGER CHEMICAL LIFETIME OF MESSENGER-RNA
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DOI：
10.1016/0022-2836(79)90500-x
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发表时间：
1979-01-01
影响因子：
5.6
通讯作者：
KUWANO, M
中科院分区：
文献类型：
--
作者：
ONO, M;KUWANO, M
对一株基因稳定性发生改变的大肠杆菌温度敏感突变体进行了分析。脉冲标记的RNA的不稳定部分在42度时以半衰期衰变。C在亲本菌株PA3092中的半衰期约为2min，在突变体HAK75中的半衰期为11-12min。腐霉素使PA3092和HAK75的降解速率提高约2倍；氯霉素的加入对两株菌的降解均有明显的抑制作用。42度时rRNA在突变细胞中的积累率。C与野生型细胞的差异不大。用十二烷基硫酸钠/蔗糖密度梯度离心法对野生型菌株的原核mRNA和色氨酸mRNA进行沉降分析表明，在42℃加入利福平后，3min和5min这两种mRNA分子的大小和水平分别迅速减小。C.在42度加入利福平后，HAK75细胞在5-12分钟内几乎保留了全长Trp和整体mRNA。C，尽管信使核糖核酸组分中的总放射性水平已降至初始活性的约60%-75%。虽然在不允许的温度下，突变株中的mRNA分子受到化学保护，但β-半乳糖苷酶和色氨酸合成酶的功能衰退速度与亲本株相当。以5倍的频率从该突变体中分离到了耐温回复菌株。10-8，这些返回体(TR1和TR2)具有不稳定RNA的正常衰减率。
An E. coli temperature-sensitive mutant with altered mRNA stability was analyzed. The unstable fraction of pulse-labeled RNA decayed with a half-life at 42.degree. C of about 2 min in the parent strain PA3092; the half-life was 11-12 min in the mutant HAK75. Puromycin enhanced the decay rate about 2-fold in PA3092 and HAK75; the addition of chloramphenicol inhibited the degradation significantly in both strains. The rate of rRNA accumulation in the mutant cells at 42.degree. C did not differ from that in the wild-type cells. Sedimentation analysis by sodium dodecyl sulfate/sucrose density-gradient centrifugation of bulk mRNA and tryptophan mRNA of the wild-type strain showed the expected rapid reduction in size and level of those mRNA molecules at 3 min and 5 min respectively, after addition of rifampicin at 42.degree. C. The cells of HAK75 retained almost full-length trp mRNA and bulk mRNA at 5-12 min after the addition of rifampicin at 42.degree. C, even though the total level of radioactivity in the mRNA fraction had decreased to about 60-75% of the initial activity. Although mRNA molecules were chemically protected at the non-permissive temperature in the mutant, the functional decay of both .beta.-galactosidase and tryptophan synthetase occurred at a rate comparable to that in the parental strain. Temperature-resistant revertants were isolated from the mutant at a frequency of 5 .times. 10-8 and these revertants (TR1 and TR2) had the normal decay rate of unstable RNA.