Taljanidisz J, Shen P, Sarkar N
Boston Biomedical Research Institute, MA 02114, USA.
Biochem Mol Biol Int. 1997 Jun;42(1):211-5. doi: 10.1080/15216549700202601.
In the light of recent evidence that the half-life of bacterial mRNA may be modulated by polyadenylation at the 3' end, we determined the half-life of polyadenylated lpp mRNA, which is an abundant and comparatively stable message encoding a major lipoprotein of the outer membrane. Messenger RNAs were pulse-labeled with [3H] adenosine and poly(A) RNA was isolated at various times after pulse-labeling by affinity chromatography on oligo(dT) cellulose. The amount of lpp mRNA remaining was quantitated by hybridization with the antisense strand of the lpp gene cloned in M13mp18. The observed half-life for polyadenylated lpp mRNA was 12 min. This represents the first half-life measurement for a specific polyadenylated mRNA in E. coli, and is slightly longer than the half-life of total lpp RNA reported earlier. It coincides with the functional half-life for lpp mRNA determined by Inouye and coworkers by measuring the rate of lipoprotein synthesis at various times after rifampicin addition. This suggest that polyadenylated lpp RNA is the predominant and translationally active form of lpp mRNA within the cell.
鉴于最近有证据表明细菌mRNA的半衰期可能受3'端多聚腺苷酸化的调节，我们测定了多聚腺苷酸化的lpp mRNA的半衰期，lpp mRNA是一种丰富且相对稳定的信使RNA，编码外膜的一种主要脂蛋白。用[3H]腺苷对信使RNA进行脉冲标记，并在脉冲标记后的不同时间通过寡聚（dT）纤维素亲和层析分离多聚（A）RNA。通过与克隆于M13mp18的lpp基因的反义链杂交来定量剩余的lpp mRNA的量。观察到多聚腺苷酸化的lpp mRNA的半衰期为12分钟。这是对大肠杆菌中特定多聚腺苷酸化mRNA的首次半衰期测量，且略长于先前报道的总lpp RNA的半衰期。它与Inouye及其同事通过测量利福平添加后不同时间的脂蛋白合成速率所确定的lpp mRNA的功能半衰期一致。这表明多聚腺苷酸化的lpp RNA是细胞内lpp mRNA的主要且具有翻译活性的形式。
