The YscE/YscG Chaperone and YscF N-Terminal sequences Target YscF to the Yersinia pestis Type III Secretion Apparatus
Yersinia pestis, Plague, Type III secretion, Chaperone, Protein secretion
The needle structures of type III secretion (T3S) systems are formed by the secretion and polymerization of a needle subunit protein, YscF in Yersinia pestis. A subset of T3S systems employ unique heterodimeric chaperones, YscE and YscG in Y. pestis, to prevent the polymerization of needle subunits within the bacterial cell. We demonstrate that the YscE/YscG chaperone is also required for stable YscF expression and for secretion of YscF. Overexpression of a functional maltose-binding protein (MBP)–YscG hybrid protein stabilized cytoplasmic YscF but YscF was not secreted in the absence of YscE. Furthermore, a YscE mutant protein was identified that functioned with YscG to stabilize cytosolic YscF; however, YscF was not secreted. These findings confirm a role for the YscE/YscG chaperone in YscF secretion and suggest that YscE may have a specific role in this process. Recent studies have shown that YscF deleted of its N-terminal 15 residues is still secreted and functional, suggesting that YscF may not require an N-terminal secretion signal. However, we demonstrate that YscF contains an N-terminal secretion signal and that a functional N-terminal signal is required for YscF secretion.
de Azevedo Souza, Clarice; Kristian L. Richards; YoSon Park; Michael Schwartz; Julie Torruellas Garcia; Sara Schesser Bartra; and Gregory V. Plano. 2018. "The YscE/YscG Chaperone and YscF N-Terminal sequences Target YscF to the Yersinia pestis Type III Secretion Apparatus." Microbiology 164, (3): 1-11. doi:10.1099/mic.0.000610.