Ton

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The Ton System
The Ton System[1]

Contents

Structure

The Ton system comprises of the triumvirate TonB/ExbB/ExbD inner membrane complex.

Function

The Ton proteins are involved in the uptake of vitamin B12 and chelated-iron into the cell[2], and the system as a whole is known to be an energy-transducing system. Each of the three proteins involved have their separate role[3]. For more information, see the respective pages for TonB, ExbB and ExbD.

The Ton system can be exploited by group B Colicins {see Colicin for more details) which include[4][5]:

It is interesting to note that the name 'Ton' comes its resistance to the T1 phage[5].

Interaction of Ton proteins

Like in the Tol complex, the Ton system proteins interact with each other[6]:

  1. the transmembrane domain of TonB interacts with both ExbB and ExbD, which contribute to the stability of the protein and support the TonB-dependent active transport across the outer membrane.
  2. ExbB and ExbD interact with each other, which has been suggested to play a part in the mechanism of energy transduction

3D structures of TonB

TonB

References

  1. ↑ Witty M, Sanz C, Shah A, Grossmann JG, Mizuguchi K, Perham RN, Luisi B. Structure of the periplasmic domain of Pseudomonas aeruginosa TolA: evidence for an evolutionary relationship with the TonB transporter protein. EMBO J. 2002 Aug 15;21(16):4207-18. PMID:12169623
  2. ↑ Cascales E, Buchanan SK, Duche D, Kleanthous C, Lloubes R, Postle K, Riley M, Slatin S, Cavard D. Colicin biology. Microbiol Mol Biol Rev. 2007 Mar;71(1):158-229. PMID:17347522 doi:10.1128/MMBR.00036-06
  3. ↑ Held KG, Postle K. ExbB and ExbD do not function independently in TonB-dependent energy transduction. J Bacteriol. 2002 Sep;184(18):5170-3. PMID:12193634
  4. ↑ Cascales E, Buchanan SK, Duche D, Kleanthous C, Lloubes R, Postle K, Riley M, Slatin S, Cavard D. Colicin biology. Microbiol Mol Biol Rev. 2007 Mar;71(1):158-229. PMID:17347522 doi:10.1128/MMBR.00036-06
  5. ↑ 5.0 5.1 Davies JK, Reeves P. Genetics of resistance to colicins in Escherichia coli K-12: cross-resistance among colicins of group B. J Bacteriol. 1975 Jul;123(1):96-101. PMID:124727
  6. ↑ Higgs PI, Myers PS, Postle K. Interactions in the TonB-dependent energy transduction complex: ExbB and ExbD form homomultimers. J Bacteriol. 1998 Nov;180(22):6031-8. PMID:9811664

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