Human RNA polymerase II subunit hsRPB7 functions in yeast and influences stress survival and cell morphology.
Human RNA polymerase II subunit hsRPB7 functions in yeast and influences stress survival and cell morphology.
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人 RNA 聚合酶 II 亚基 hsRPB7 在酵母中发挥作用，并影响应激存活和细胞形态。
DOI：
10.1091/mbc.6.7.759
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发表时间：
1995
影响因子：
3.3
通讯作者：
Golemis,EA
中科院分区：
文献类型：
--
作者：
Khazak,V;Sadhale,PP;Woychik,NA;Brent,R;Golemis,EA
通过在酿酒酵母中筛选促进假菌丝转化的人类基因，我们获得了编码hsRPB7的cDNA，hsRPB7是酵母RNA聚合酶II(RPB7)第七大亚基的人类同源物。在可比菌株背景中，酵母RPB7的过表达比hsRPB7的过表达导致更明显的细胞伸长。HsRPB7的序列和功能与酵母高度保守，因为它的表达可以在中等温度下挽救必要的RPB7基因的缺失。此外，从含有hsRPB7的酵母细胞中免疫沉淀RNA聚合酶II发现，hsRPB7组装了另外11个酵母亚基的完整集合。然而，在极端的温度下和在稳定期保持期间，含有hsRPB7的酵母细胞迅速失去活力，压力敏感的表型使人想起那些与RPB4亚基缺失相关的RPB4亚基，RPB7通常与之复合。双杂交分析表明，尽管hsRPB7和RPB4相互作用，但这种结合的亲和力低于RPB4-RPB7，这可能是hsRPB7在高温和低温下无法在酵母细胞中充分发挥功能的机制。最后，令人惊讶的是，hsRPB7 RNA在人类细胞中以不同于RNA聚合酶II最大亚基的组织特异性模式表达，这意味着hsRPB7可能具有调节作用。综上所述，这些结果表明，RPB7的某些功能可能类似于原核特异的Sigma因子rpos所具有的功能。
Using a screen to identify human genes that promote pseudohyphal conversion in Saccharomyces cerevisiae, we obtained a cDNA encoding hsRPB7, a human homologue of the seventh largest subunit of yeast RNA polymerase II (RPB7). Overexpression of yeast RPB7 in a comparable strain background caused more pronounced cell elongation than overexpression of hsRPB7. hsRPB7 sequence and function are strongly conserved with its yeast counterpart because its expression can rescue deletion of the essential RPB7 gene at moderate temperatures. Further, immuno-precipitation of RNA polymerase II from yeast cells containing hsRPB7 revealed that the hsRPB7 assembles the complete set of 11 other yeast subunits. However, at temperature extremes and during maintenance at stationary phase, hsRPB7-containing yeast cells lose viability rapidly, stress-sensitive phenotypes reminiscent of those associated with deletion of the RPB4 subunit with which RPB7 normally complexes. Two-hybrid analysis revealed that although hsRPB7 and RPB4 interact, the association is of lower affinity than the RPB4-RPB7 interaction, providing a probable mechanism for the failure of hsRPB7 to fully function in yeast cells at high and low temperatures. Finally, surprisingly, hsRPB7 RNA in human cells is expressed in a tissue-specific pattern that differs from that of the RNA polymerase II largest subunit, implying a potential regulatory role for hsRPB7. Taken together, these results suggest that some RPB7 functions may be analogous to those possessed by the stress-specific prokaryotic sigma factor rpoS.