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Eugenia M Clerico
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Newly synthesized proteins destined for non-cytoplasmic locations contain in
their primary sequences targeting information that specifies their
localization in the cell. Proteins which are secreted or inserted into the
cell membrane bear an N terminal extension named "signal sequence". In E.
coli, nascent polypeptide chains containing highly hydrophobic N terminal
signal sequences bind to the E. coli signal recognition particle (SRP), a
complex of the Ffh protein and a 4.5S RNA. SRP is essential for cell viability
and efficient protein export. The initial step in the SRP mediated secretory
pathway is the recognition of the signal sequence. The mechanisms underlying
specific recognition, binding and release of signal sequences remain unclear.
It has been proposed that the signal peptide binds in a "cleft" at the
interface between the two main domains of Ffh (M and NG domain). My research
proposal involves the study of the interactions between Ffh protein and the
signal peptide. By using chemical cross linking, fluorescence resonance energy
transfer (FRET) and transferred NOE, I plan to elucidate the conformation that
the signal peptide adopts upon interaction with Ffh and locate the peptide
binding site in Ffh.
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