Zheng N, Gierasch L M
Molecular Biophysics Program, University of Texas Southwestern Medical Center at Dallas 75235, USA.
Mol Cell. 1997 Dec;1(1):79-87. doi: 10.1016/s1097-2765(00)80009-x.
The E. coli protein, Fth, binds to 4.5S RNA through its M domain to form the signal recognition particle (SRP). The other domain of Fth (NG) is a GTPase, which binds and is coordinately regulated by its receptor, FtsY. We find that the helical M domain is inherently flexible. Binding of 4.5S RNA to Fth stabilizes the M domain yet has little apparent effect on the binding of signal peptides. However, in the absence of the RNA, signal peptide binding results in a global destabilization of Fth, which is prevented by binding of 4.5S RNA. Signal peptide binding to isolated NG domain also causes a pronounced destabilization, implicating the NG domain in direct recognition of signal peptide.
大肠杆菌蛋白Fth通过其M结构域与4.5S RNA结合，形成信号识别颗粒（SRP）。Fth的另一个结构域（NG）是一种GTP酶，它与其受体FtsY结合并受到协同调节。我们发现螺旋状的M结构域具有内在的灵活性。4.5S RNA与Fth的结合使M结构域稳定，但对信号肽的结合几乎没有明显影响。然而，在没有RNA的情况下，信号肽的结合会导致Fth整体不稳定，而4.5S RNA的结合可防止这种情况发生。信号肽与分离的NG结构域结合也会导致明显的不稳定，这表明NG结构域参与信号肽的直接识别。
