TolA: Difference between revisions
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TolA is located in the inner membrane and comprises of three domains: the N-terminal domain I (TolAI), from residues 1-47 including a 20-residue hydrophobic membrane spanning region which anchors the protein to the cytoplasmic membrane<ref>PMID: 7853390</ref>; domain II (TolAII), from residues 48-301, which forms a rigid helix connecting the domains either side of it; and the C-terminal domain III (TolAIII) from residues 302-421, which may be involved in the function of TolA by interacting with the periplasmic or outer membrane proteins, due to the tethering to domain II.<ref name='Sharyn'>PMID: 8416897</ref> | TolA is located in the inner membrane and comprises of three domains: the N-terminal domain I (TolAI), from residues 1-47 including a 20-residue hydrophobic membrane spanning region which anchors the protein to the cytoplasmic membrane<ref>PMID: 7853390</ref>; domain II (TolAII), from residues 48-301, which forms a rigid helix connecting the domains either side of it; and the C-terminal domain III (TolAIII) from residues 302-421, which may be involved in the function of TolA by interacting with the periplasmic or outer membrane proteins, due to the tethering to domain II.<ref name='Sharyn'>PMID: 8416897</ref> | ||
===C-terminal Domain=== | ====C-terminal Domain==== | ||
The c-terminal domain of TolA is directly involved with the N-terminal of both [[Colicin]] and the phage minor coat gene 3 protein. <ref>PMID: 15701516</ref> | The c-terminal domain of TolA is directly involved with the N-terminal of both [[Colicin]] and the phage minor coat gene 3 protein. <ref>PMID: 15701516</ref> | ||
Revision as of 12:10, 25 April 2011
StructureStructure
TolA is located in the inner membrane and comprises of three domains: the N-terminal domain I (TolAI), from residues 1-47 including a 20-residue hydrophobic membrane spanning region which anchors the protein to the cytoplasmic membrane[1]; domain II (TolAII), from residues 48-301, which forms a rigid helix connecting the domains either side of it; and the C-terminal domain III (TolAIII) from residues 302-421, which may be involved in the function of TolA by interacting with the periplasmic or outer membrane proteins, due to the tethering to domain II.[2]
C-terminal DomainC-terminal Domain
The c-terminal domain of TolA is directly involved with the N-terminal of both Colicin and the phage minor coat gene 3 protein. [3]
FunctionFunction
Although the exact function of TolA is not yet known, it has been shown that unlike mutations in the proteins of the TonB system to which the TolQRA proteins show many similarities, mutations in the TolQRA proteins affect the outer membrane integrity. TolA could be involved structurally by bringing the inner and outer membranes together and forming a bridge or link between them.[2]
TolA plays an important role in the import mechanisms for the uptake of bacteriotoxins (see Colicin) and the DNA of filamentous bacteriophages[4], and has also been shown to be involved in the bacterial sensitivity to these groups[5], in particular the alpha helix of domain II, the deletion of which causes increased cellular sensitivity to deoxycholate (a detergent)[6].
TolA and Colicin UptakeTolA and Colicin Uptake
Studies have shown that TolAIII plays an important role in the uptake mechanisms of colicin and DNA by being directly involved with the N-terminal of both colicin and the phage minor coat gene 3 protein. [7]
TolA interacts with different group A colicins in different ways[6]:
- Colicin E1 requires different structural features of TolA to be transported than the other group A colicins, including E3, N and A. Colicin E3 requires the C-terminus of TolA, which it finds with ease even when the terminus is attached very close to the membrane-spanning domain, by means of utilising a different outer membrane receptor complex to that of the other colicins
- The other colicins require additional receptors in order to bind initially to the outer membrane
- Colicin E1 also does not require as high of TolA levels than the other colicins in order for translocation to occur
ReferencesReferences
- ↑ Lazzaroni JC, Vianney A, Popot JL, Benedetti H, Samatey F, Lazdunski C, Portalier R, Geli V. Transmembrane alpha-helix interactions are required for the functional assembly of the Escherichia coli Tol complex. J Mol Biol. 1995 Feb 10;246(1):1-7. PMID:7853390 doi:http://dx.doi.org/10.1006/jmbi.1994.0058
- ↑ 2.0 2.1 Levengood-Freyermuth SK, Click EM, Webster RE. Role of the carboxyl-terminal domain of TolA in protein import and integrity of the outer membrane. J Bacteriol. 1993 Jan;175(1):222-8. PMID:8416897
- ↑ Deprez C, Lloubes R, Gavioli M, Marion D, Guerlesquin F, Blanchard L. Solution structure of the E.coli TolA C-terminal domain reveals conformational changes upon binding to the phage g3p N-terminal domain. J Mol Biol. 2005 Mar 4;346(4):1047-57. Epub 2005 Jan 12. PMID:15701516 doi:10.1016/j.jmb.2004.12.028
- ↑ Deprez C, Lloubes R, Gavioli M, Marion D, Guerlesquin F, Blanchard L. Solution structure of the E.coli TolA C-terminal domain reveals conformational changes upon binding to the phage g3p N-terminal domain. J Mol Biol. 2005 Mar 4;346(4):1047-57. Epub 2005 Jan 12. PMID:15701516 doi:10.1016/j.jmb.2004.12.028
- ↑ Lazzaroni JC, Vianney A, Popot JL, Benedetti H, Samatey F, Lazdunski C, Portalier R, Geli V. Transmembrane alpha-helix interactions are required for the functional assembly of the Escherichia coli Tol complex. J Mol Biol. 1995 Feb 10;246(1):1-7. PMID:7853390 doi:http://dx.doi.org/10.1006/jmbi.1994.0058
- ↑ 6.0 6.1 Schendel SL, Click EM, Webster RE, Cramer WA. The TolA protein interacts with colicin E1 differently than with other group A colicins. J Bacteriol. 1997 Jun;179(11):3683-90. PMID:9171417
- ↑ Deprez C, Lloubes R, Gavioli M, Marion D, Guerlesquin F, Blanchard L. Solution structure of the E.coli TolA C-terminal domain reveals conformational changes upon binding to the phage g3p N-terminal domain. J Mol Biol. 2005 Mar 4;346(4):1047-57. Epub 2005 Jan 12. PMID:15701516 doi:10.1016/j.jmb.2004.12.028