TY - JOUR
T1 - The third transmembrane domain of EscR is critical for function of the enteropathogenic Escherichia coli type III secretion system
AU - Tseytin, Irit
AU - Madar, Adi
AU - Mitrovi, Bosko
AU - Deng, Wanyin
AU - Finlay, B. Brett
AU - Sal-Man, Neta
N1 - Publisher Copyright:
© 2018 Tseytin et al.
PY - 2018/7/1
Y1 - 2018/7/1
N2 - Many Gram-negative bacterial pathogens utilize a specialized protein delivery system, called the type III secretion system (T3SS), to translocate effector proteins into the host cells. The translocated effectors are crucial for bacterial infection and survival. The base of the T3SS transverses both bacterial membranes and contains an export apparatus that comprises five membrane proteins. Here, we study the export apparatus of enteropathogenic Escherichia coli (EPEC) and characterize its central component, called the EscR protein. We found that the third transmembrane domain (TMD) of EscR mediates strong self-oligomerization in an isolated genetic reporter system. Replacing this TMD sequence with an alternative hydrophobic sequence within the full-length protein resulted in a complete loss of function of the T3SS, further suggesting that the EscR TMD3 sequence has another functional role in addition to its role as a membrane anchor. Moreover, we found that an aspartic acid residue, located at the core of EscR TMD3, is important for the oligomerization propensity of TMD3 and that a point mutation of this residue within the full-length protein abolishes the T3SS activity and the ability of the bacteria to translocate effectors into host cells.
AB - Many Gram-negative bacterial pathogens utilize a specialized protein delivery system, called the type III secretion system (T3SS), to translocate effector proteins into the host cells. The translocated effectors are crucial for bacterial infection and survival. The base of the T3SS transverses both bacterial membranes and contains an export apparatus that comprises five membrane proteins. Here, we study the export apparatus of enteropathogenic Escherichia coli (EPEC) and characterize its central component, called the EscR protein. We found that the third transmembrane domain (TMD) of EscR mediates strong self-oligomerization in an isolated genetic reporter system. Replacing this TMD sequence with an alternative hydrophobic sequence within the full-length protein resulted in a complete loss of function of the T3SS, further suggesting that the EscR TMD3 sequence has another functional role in addition to its role as a membrane anchor. Moreover, we found that an aspartic acid residue, located at the core of EscR TMD3, is important for the oligomerization propensity of TMD3 and that a point mutation of this residue within the full-length protein abolishes the T3SS activity and the ability of the bacteria to translocate effectors into host cells.
KW - Enteropathogenic E. coli
KW - Export apparatus
KW - Inner membrane proteins
KW - Transmembrane domain
KW - Type III secretion system
UR - http://www.scopus.com/inward/record.url?scp=85056720359&partnerID=8YFLogxK
U2 - 10.1128/MSPHERE.00162-18
DO - 10.1128/MSPHERE.00162-18
M3 - Article
AN - SCOPUS:85056720359
SN - 2379-5042
VL - 3
JO - mSphere
JF - mSphere
IS - 4
M1 - e00162-18
ER -