Soto M, Quijada L, Alonso C, Requena J M
Centro de Biología Molecular 'Severo Ochoa', Facultad de Ciencias, Universidad Autónoma de Madrid, 28049 Madrid, Spain.
Biochem J. 2000 Feb 15;346 Pt 1(Pt 1):99-105.
We have analysed the regulation of histone synthesis in Leishmania infantum following inhibition of DNA replication. Run-on experiments indicated that transcription rates of the genes coding for the four core histones (H2A, H2B, H3 and H4) were not affected by the inhibition with hydroxyurea of DNA synthesis. However, a dramatic decrease was observed in the newly synthesized histones after inhibition of DNA synthesis. Furthermore, the synthesis of both the histones and DNA resumed in promastigotes after removal of hydroxyurea, indicating that inhibition was reversible. Unlike most eukaryotes, in which the replication-dependent histone transcripts decrease upon a replication blockade, the levels of L. infantum histone mRNAs do not change under similar conditions. Thus the present data indicate that histone synthesis in Leishmania is tightly coupled to DNA replication by a mechanism operating at the translational level.
我们分析了婴儿利什曼原虫在DNA复制受到抑制后组蛋白合成的调控情况。连续转录实验表明,编码四种核心组蛋白(H2A、H2B、H3和H4)的基因转录速率不受羟基脲抑制DNA合成的影响。然而,在DNA合成受到抑制后,新合成的组蛋白显著减少。此外,去除羟基脲后,前鞭毛体中组蛋白和DNA的合成均恢复,表明这种抑制是可逆的。与大多数真核生物不同,在大多数真核生物中,复制依赖性组蛋白转录本在复制受阻时会减少,而在类似条件下,婴儿利什曼原虫组蛋白mRNA的水平并未改变。因此,目前的数据表明,利什曼原虫中的组蛋白合成通过一种在翻译水平起作用的机制与DNA复制紧密偶联。