TonB/TolA, C-terminal (IPR006260)

Short name: TonB/TolA_C

Overlapping homologous superfamilies


Domain relationships



TonB is bound to an inner membrane-bound protein ExbB via a globular domain and has a flexible middle region that is likely to help in positioning the C-terminal domain into the iron-transporter barrel in the outer membrane [PMID: 16741124].

This entry represents the C-terminal domain of TonB. TonB_C interacts with the N-terminal TonB box of the outer membrane transporter that binds the Fe3+-siderophore complex. The barrel of the transporter, consisting of 22 beta-sheets and an inside plug, binds the iron complex in the barrel entrance [PMID: 21277822].

TonB-C domain is characteristic of TonB and its homologues. Most members are designated as TonB or TonB-related proteins, but a few represent the paralogous TolA protein. Several bacteria have up to four TonB paralogs. In nearly every case, a proline-rich repetitive region is found N-terminal to this domain; this low-complexity region is highly divergent and is suggested to span the periplasm. The TolA and TonB C-terminal domains adopt a structure containing anti-parallel beta sheets with some alpha helical regions. TolA contains an extra N-terminal helix over the common fold [PMID: 15644214].

GO terms

Biological Process

GO:0006810 transport

Molecular Function

No terms assigned in this category.

Cellular Component

No terms assigned in this category.

Contributing signatures

Signatures from InterPro member databases are used to construct an entry.