A modular strategy for the assembly of farnesylated N-Ras heptapeptides carrying a photo-activatable benzophenone (BP) group within the lipid residue is described. This strategy is based on the fragment condensation of a N-terminal hexapeptide synthesized on the solid support with a cysteine methyl ester which is modified with different farnesyl analogues, incorporating the photophor. At the N-terminus of the peptides different functional groups can be attached, e.g., biotin for product enrichment and detection after photoactivation or a maleimido (MIC) linker, allowing for the coupling to proteins carrying a C-terminal free cysteine. Using this strategy, 24 peptides were synthesized, incorporating famesyl analogues with four different chain lengths. Two of these photoactivatable conjugates were ligated to oncogenic human N-RasG12VDelta181. A cellular transformation assay revealed that the semisynthetic proteins retain their biological activity despite the photolabel. The first photolabeling experiments with a geranyl-BP-labeled N-Ras construct and the farnesyl-sensitive guanine nucleotide exchange factor hSos1 indicate that this photoaffinity labeling system can be particularly useful for studying protein-protein interactions, e.g., the participation of the farnesyl group in Ras signaling, which is still discussed with controversy.
Photoactive Analogs of Farnesyl Pyrophosphate Containing Benzoylbenzoate Esters: Synthesis and Application to Photoaffinity Labeling of Yeast Protein Farnesyltransferase
作者:Igor Gaon、Tammy C. Turek、Valerie A. Weller、Rebecca L. Edelstein、Satinder K. Singh、Mark D. Distefano
DOI:10.1021/jo9602736
日期:1996.1.1
Farnesylpyrophosphate (FPP) is involved in a large number of cellular processes including the prenylation of transforming mutants of Ras proteins implicated in cancer. Photoactive analogs could provide useful information about enzyme active sites that bind farnesylpyrophosphate; however, the availability of such compounds is extremely limited. Molecules that incorporate benzophenone moieties are