Dynamic studies of H-Rasâ¢GTPγS interactions with nucleotide exchange factor Sos reveal a transient ternary complex formation in solution.
Sci Rep
; 6: 29706, 2016 07 14.
Article
en En
| MEDLINE
| ID: mdl-27412770
ABSTRACT
The cycling between GDP- and GTP- bound forms of the Ras protein is partly regulated by the binding of Sos. The structural/dynamic behavior of the complex formed between activated Sos and Ras at the point of the functional cycle where the nucleotide exchange is completed has not been described to date. Here we show that solution NMR spectra of H-RasâGTPγS mixed with a functional fragment of Sos (Sos(Cat)) at a 21 ratio are consistent with the formation of a rather dynamic assembly. H-RasâGTPγS binding was in fast exchange on the NMR timescale and retained a significant degree of molecular tumbling independent of Sos(Cat), while Sos(Cat) also tumbled largely independently of H-Ras. Estimates of apparent molecular weight from both NMR data and SEC-MALS revealed that, at most, only one H-RasâGTPγS molecule appears stably bound to Sos. The weak transient interaction between Sos and the second H-RasâGTPγS may provide a necessary mechanism for complex dissociation upon the completion of the native GDP â GTP exchange reaction, but also explains measurable GTP â GTP exchange activity of Sos routinely observed in in vitro assays that use fluorescently-labelled analogs of GTP. Overall, the data presents the first dynamic snapshot of Ras functional cycle as controlled by Sos.
Texto completo:
1
Colección:
01-internacional
Base de datos:
MEDLINE
Asunto principal:
Guanosina 5'-O-(3-Tiotrifosfato)
/
Proteínas Proto-Oncogénicas p21(ras)
/
Proteína SOS1
/
Complejos Multiproteicos
Tipo de estudio:
Prognostic_studies
Límite:
Humans
Idioma:
En
Revista:
Sci Rep
Año:
2016
Tipo del documento:
Article
País de afiliación:
Reino Unido