Protein Family Models

TonB from Escherichia coli and its homologues are critical for the uptake of siderophores through the outer membrane of Gram-negative bacteria using chemiosmotic energy. The proline-rich segment of TonB exists in a PPII-like conformation [1]. The result implies that the proline-rich segment of TonB possesses a length of more than 15 nm, sufficient to span the periplasm of Gram-negative bacteria. [1]. 20095050. The proline-rich domain of TonB possesses an extended. polyproline II-like conformation of sufficient length to span. the periplasm of Gram-negative bacteria.. Kohler SD, Weber A, Howard SP, Welte W, Drescher M;. Protein Sci. 2010;19:625-630. (from Pfam)

Date:

2024-08-14

The TonB_C domain is the well-characterised C-terminal region of the TonB receptor molecule. This protein 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 [1]. 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 [2]. [1]. 16741124. Outer membrane active transport: structure of the BtuB:TonB. complex.. Shultis DD, Purdy MD, Banchs CN, Wiener MC;. Science. 2006;312:1396-1399.. [2]. 21277822. Recent insights into iron import by bacteria.. Braun V, Hantke K;. Curr Opin Chem Biol. 2011;15:328-334. (from Pfam)

Date:

2024-08-14

energy transducer TonB interacts with outer membrane receptor proteins that carry out high-affinity binding and energy dependent uptake into the periplasmic space of specific substrates such as cobalamin, and various iron compounds (such as iron dicitrate, enterochelin, aerobactin, etc.)

Date:

2017-08-28

This HMM represents the C-terminal of TonB and is homologs. TonB is an energy-transducer for TonB-dependent receptors of Gram-negative bacteria. 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 repetive region is found N-terminal to this domain; these low-complexity regions are highly divergent and cannot readily be aligned. The region is suggested to help span the periplasm.

Date:

2021-05-12

Gene:

tonB

Date:

2022-01-26