Host factor I, Hfq, binds to Escherichia coli ompA mRNA in a growth rate dependent fashion and regulates its stability

被引:105
作者
Vytvytska, O
Jakobsen, JS
Balcunaite, G
Andersen, JS
Baccarini, M
von Gabain, A
机构
[1] Univ Vienna, Vienna Bioctr, Inst Genet & Microbiol, A-1030 Vienna, Austria
[2] Inst Biol Struct, F-38027 Grenoble 1, France
关键词
RNA-binding protein; mobility-shift assay; hfq mutants; mRNA half-life;
D O I
10.1073/pnas.95.24.14118
中图分类号
O [数理科学和化学]; P [天文学、地球科学]; Q [生物科学]; N [自然科学总论];
学科分类号
07 ; 0710 ; 09 ;
摘要
The stability of the ompA mRNA depends on the bacterial growth rate. The 5' untranslated region is the stability determinant of this transcript and the target of the endoribonuclease, RNase E, the key player of mRNA degradation. An RNA-binding protein with affinity for the 5' untranslated region ompA was purified and identified as Hfq, a host factor initially recognized for its function in phage Q beta replication. The ompA RNA-binding activity parallels the amount of Hfq, which is elevated in bacteria cultured at slow growth rate, a condition leading to facilitated degradation of the ompA mRNA. In hfq mutant cells with a deficient Hfq gene product, the RNA-binding activity is missing, and analysis of the ompA mRNA showed that the growth-rate dependence of degradation is lost. Furthermore, the half-life of the ompA mRNA is prolonged in the mutant cells, irrespective of growth rate. Hfq has no affinity for the Ipp transcript whose degradation, like that of bulk mRNA is not affected by bacterial growth rate. Compatible with our results, we found that the intracellular concentration of RNase E and its associated degradosome components is independent of bacterial growth rate. Thus our results suggest a regulatory role for Hfq that specifically facilitates the ompA mRNA degradation in a growth rate dependent manner.
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页码:14118 / 14123
页数:6
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