Laboratoire de Microbiologie et Génétique Moléculaires, UMR 5100, Centre National de la Recherche Scientifique et Université de Toulouse 3, 31062 Toulouse, France.
J Bacteriol. 2010 Oct;192(20):5413-23. doi: 10.1128/JB.00592-10. Epub 2010 Aug 20.
The degradosome is a multienzyme complex involved in mRNA degradation in Escherichia coli. The essential endoribonuclease RNase E contains a large noncatalytic region necessary for protein-protein interactions with other components of the RNA degradosome. Interacting proteins include the DEAD-box RNA helicase RhlB, the glycolytic enzyme enolase, and the exoribonuclease PNPase. Pseudoalteromonas haloplanktis, a psychrotolerant gammaproteobacterium distantly related to E. coli, encodes homologs of each component of the RNA degradosome. In P. haloplanktis, RNase E associates with RhlB and PNPase but not enolase. Plasmids expressing P. haloplanktis RNase E (Ph-RNase E) can complement E. coli strains lacking E. coli RNase E (Ec-RNase E). Ph-RNase E, however, does not confer a growth advantage to E. coli at low temperature. Ph-RNase E has a heterologous protein-protein interaction with Ec-RhlB but not with Ec-enolase or Ec-PNPase. The Ph-RNase E binding sites for RhlB and PNPase were mapped by deletion analysis. The PNPase binding site is located at the C-terminal end of Ph-RNase E at the same position as that in Ec-RNase E, but the sequence of the site is not conserved. The sequence of the RhlB binding site in Ph-RNase E is related to the sequence in Ec-RNase E. Together with the heterologous interaction between Ph-RNase E and Ec-RhlB, our results suggest that the underlying structural motif for the RNase E-RhlB interaction is conserved. Since the activity of Ec-RhlB requires its physical interaction with Ec-RNase E, conservation of the underlying structural motif over a large evolutionary distance could be due to constraints involved in the control of RhlB activity.
降解体是一种多酶复合物，参与大肠杆菌中 mRNA 的降解。必需的内切核糖核酸酶 RNase E 包含一个大的非催化区域，该区域对于与 RNA 降解体的其他成分的蛋白质-蛋白质相互作用是必需的。相互作用的蛋白质包括 DEAD 盒 RNA 解旋酶 RhlB、糖酵解酶烯醇酶和外切核糖核酸酶 PNPase。远缘相关的嗜冷γ变形菌假交替单胞菌编码 RNA 降解体的每个成分的同源物。在假交替单胞菌中，RNase E 与 RhlB 和 PNPase 结合，但不与烯醇酶结合。表达假交替单胞菌 RNase E（Ph-RNase E）的质粒可以补充缺乏大肠杆菌 RNase E（Ec-RNase E）的大肠杆菌菌株。然而，Ph-RNase E 不能在低温下赋予大肠杆菌生长优势。Ph-RNase E 与 Ec-RhlB 具有异源的蛋白质-蛋白质相互作用，但与 Ec-烯醇酶或 Ec-PNPase 没有。通过缺失分析定位了 Ph-RNase E 与 RhlB 和 PNPase 的结合位点。PNPase 的结合位点位于 Ph-RNase E 的 C 末端，与 Ec-RNase E 相同位置，但该位点的序列没有保守性。Ph-RNase E 中 RhlB 结合位点的序列与 Ec-RNase E 中的序列相关。与 Ph-RNase E 与 Ec-RhlB 的异源相互作用一起，我们的结果表明，RNase E-RhlB 相互作用的基础结构基序是保守的。由于 Ec-RhlB 的活性需要其与 Ec-RNase E 的物理相互作用，因此在很大的进化距离上保守的基础结构基序可能是由于控制 RhlB 活性所涉及的约束。
