Domain interactions in E. coli SRP: stabilization of M domain by RNA is required for effective signal sequence modulation of NG domain.
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.
Zheng
N
N
Molecular Biophysics Program, University of Texas Southwestern Medical Center at Dallas 75235, USA.
Gierasch
L M
LM
D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D001665:Binding Sites / Q000502:physiology; D004926:Escherichia coli / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D029968:Escherichia coli Proteins; D020558:GTP Phosphohydrolases / Q000378:metabolism; D008969:Molecular Sequence Data; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D012329:RNA, Bacterial / Q000378:metabolism*; D018271:Signal Recognition Particle / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism
D001426:Bacterial Proteins; D029968:Escherichia coli Proteins; C082931:Ffh protein, E coli; D012329:RNA, Bacterial; D018271:Signal Recognition Particle; D020558:GTP Phosphohydrolases