Abstract
Interactions among the
Yersinia secretion (Ysc) proteins of
Yersinia pestis were explored using the yeast two-hybrid system. Various pairwise combinations of the
yscEFGHIKLN and
Q genes fused to the DNA-binding or activation domain of the yeast GAL4 gene were introduced into yeast, and expression of a reporter gene encoding β-galactosidase was detected. Combinations of
yscN and
yscL,
yscL and
yscQ, and
yscQ and
yscK resulted in high levels of reporter gene activation. These results suggest that YscL interacts with both YscN and YscQ, and that YscQ interacts with both YscL and YscK. Three-hybrid analyses using plasmid pDELA to target a third hybrid protein to the yeast nucleus was used to detect the formation of ternary protein complexes. Using the three-hybrid system, YscQ expressed from plasmid pDELA was able to bring together the YscK and YscL fusion proteins. In a similar manner, YscL expressed from plasmid pDELA was able to bring together the YscN and YscQ fusion proteins. Together, these results suggest that a complex composed of YscN, YscQ, YscK and YscL is involved in the assembly and/or function of the
Y. pestis type III secretion apparatus.
