2.C.1.2.1 The TolA energy-transducing system. The H+-channel-forming
TolQ/R proteins are listed under TC# 1.A.30.2.2. Proteins of the
complex listed here are TolA, TolB, YbgF and Pal. They play a role in
outer membrane stabilization and uptake of colicins, but not energizaton
of outer membrane receptors (OMRs: TC# 1.B.14). May function in
phospholipid transport (SS Chng, personal communication). Cells lacking
the Tol-Pal complex exhibit defects in lipid asymmetry and
accumulate excess phospholipids (PLs) in the OM. This imbalance in OM
lipids is due to defective retrograde PL transport in the absence of a
functional Tol-Pal complex. Thus, cells ensure the assembly of a stable
OM by maintaining an excess flux of PLs to the OM only to return the
surplus to the inner membrane via transport mediated by the Tol-Pal
complex (Shrivastava et al. 2017).
The specific function of the Tol-Pal complex may be to transport lipids
from the outer leaflet of the outer membrane to the inner leaflet of
the outer member. The Tol-Pal complex is essential to maintain polar
localization of the MCP chemotaxis receptor complex (Santos et al. 2014). The Tol-Pal complex, energized by TolQRA, and using the outer membrane proteins, BtuB and OmpF as receptors, is responsible for the uptake of colicin ColE9 and other bacteriocins; in this process, the complex in the outer membrane bridges and immobilizes the complex components in the inner membrane (Rassam et al. 2018).
|
Accession Number: | P0A855 |
Protein Name: | Protein TolB |
Length: | 430 |
Molecular Weight: | 45956.00 |
Species: | Escherichia coli (strain K12) [83333] |
Number of TMSs: | 1 |
Location1 / Topology2 / Orientation3: |
Periplasm1 |
Substrate |
phospholipid |
---|
1: MKQALRVAFG FLILWASVLH AEVRIVIDSG VDSGRPIGVV PFQWAGPGAA PEDIGGIVAA
61: DLRNSGKFNP LDRARLPQQP GSAQEVQPAA WSALGIDAVV VGQVTPNPDG SYNVAYQLVD
121: TGGAPGTVLA QNSYKVNKQW LRYAGHTASD EVFEKLTGIK GAFRTRIAYV VQTNGGQFPY
181: ELRVSDYDGY NQFVVHRSPQ PLMSPAWSPD GSKLAYVTFE SGRSALVIQT LANGAVRQVA
241: SFPRHNGAPA FSPDGSKLAF ALSKTGSLNL YVMDLASGQI RQVTDGRSNN TEPTWFPDSQ
301: NLAFTSDQAG RPQVYKVNIN GGAPQRITWE GSQNQDADVS SDGKFMVMVS SNGGQQHIAK
361: QDLATGGVQV LSSTFLDETP SLAPNGTMVI YSSSQGMGSV LNLVSTDGRF KARLPATDGQ
421: VKFPAWSPYL