The
structures of the SRP GTPases Ffh and FtsY have suggested new mechanisms by
which function can be elaborated from a common GTPase fold. The structure of the heterodimeric
complex of Ffh and FtsY was first determined in our laboratory in 2003.
It revealed a remarkably symmetric 'homo'heterodimer assembly mechanism
that directly couples the active sites of the two proteins. Our laboratory is now focusing on
understanding the structural basis for regulation of the two SRP GTPases, using
high resolution X-ray crystallographic studies of the nucleotide-bound Ffh and biochemical, biophysical and crystallographic studies of
the assembly of the Ffh:FtsY targeting complex.
The long term aims are to understand the specific role of the two SRP GTPases in the biology of the cell, and to understand the general principles by which the protein architecture of the GTPase fold provides means for diverse members of the GTPase superfamily to play critical roles in the transduction of cellular signals and the assembly of macromolecular complexes.
Publications:
(2006)
Ramirez et
al., Analysis of protein hydration
in ultra-high resolution structures of the SRP GTPase Ffh Acta
Cryst. Sect. D In
Press.
(2002)
Ramirez, et al., Structural basis for mobility in the
1.1Å crystal structure of the NG domain of T. aquaticus
Ffh J. Mol. Biol. 320 783.
Grant Support: NIH R01 GM058500