Synthesis of functional signaling domains by combinatorial polymerization of phosphorylation motifs.
The adaptor protein Cas contains a core substrate domain with multiple YXXP motifs that are phosphorylated by Src and other tyrosine kinases. Here, we used a synthetic strategy to determine the importance of the arrangement, spacing, and identity of the YXXP motifs. By polymerizing short DNA sequences encoding two phosphorylation motifs, we created a panel of Cas mutants in which the entire substrate domain was replaced by synthetic domains containing random numbers and arrangements of the motifs. Most of these synthetic Cas variants were recognized and phosphorylated by Src in vitro and in intact mammalian cells. The random polymer mutants also restored migration activity to Cas knockout cells; even artificial proteins containing a single motif retained some biological function. Our results suggest that the arrangement of Cas motifs is not critical for signaling. This method could be used to identify the minimal functional units in other signaling proteins.
Patwardhan
Parag
P
Department of Physiology and Biophysics, School of Medicine, State University of New York at Stony Brook, Stony Brook, New York 11794, USA.
Shiba
Kiyotaka
K
Gordon
Chris
C
Craddock
Barbara P
BP
Tamiko
Minamisawa
M
Miller
W Todd
WT
D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D000818:Animals; D002460:Cell Line; D002465:Cell Movement; D050719:Crk-Associated Substrate Protein / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D004926:Escherichia coli / Q000235:genetics; D008969:Molecular Sequence Data; D009154:Mutation; D010766:Phosphorylation; D017434:Protein Structure, Tertiary; D019061:src-Family Kinases / Q000378:metabolism
D050719:Crk-Associated Substrate Protein; D019061:src-Family Kinases