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15  structures 6079  species 0  interactions 13561  sequences 21  architectures

Family: TatA_B_E (PF02416)

Summary: mttA/Hcf106 family

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This is the Wikipedia entry entitled "Twin-arginine translocation pathway". More...

Twin-arginine translocation pathway Edit Wikipedia article

OPM superfamily63
OPM protein4b4a
OPM superfamily63
OPM protein2l16

The twin-arginine translocation pathway (Tat pathway) is a protein export, or secretion pathway found in plants, bacteria, and archaea. In contrast to the Sec pathway which transports proteins in an unfolded manner, the Tat pathway serves to actively translocate folded proteins across a lipid membrane bilayer. In plants, the Tat translocase is located in the thylakoid membrane of the chloroplast, where it acts to export proteins into the thylakoid lumen. In bacteria, the Tat translocase is found in the cytoplasmic membrane and serves to export proteins to the cell envelope, or to the extracellular space.[1] The existence of a Tat translocase in plant mitochondria is also proposed.[2][3]

In the plant thylakoid membrane and in Gram-negative bacteria the Tat translocase is composed of three essential membrane proteins; TatA, TatB, and TatC. In the most widely studied Tat pathway, that of the Gram-negative bacterium Escherichia coli, these three proteins are expressed from an operon with a fourth Tat protein, TatD, which is not required for Tat function. A fifth Tat protein TatE that is homologous to the TatA protein is present at a much lower level in the cell than TatA and is not believed to play any significant role in Tat function.

The Tat pathways of Gram-positive bacteria differ in that they do not have a TatB component. In these bacteria the Tat system is made up from a single TatA and TatC component, with the TatA protein being bifunctional and fulfilling the roles of both E. coli TatA and TatB.[4]

The name of the Tat pathway relates to a highly conserved twin-arginine leader motif (S/TRRXFLK) which is found in the N terminal Signal peptide of the corresponding passenger proteins.[5] The signal peptide is removed by a signal peptidase after release of the transported protein from the Tat complex.[6] At least two TatC molecules co-exist within each Tat translocon.[7][8]

In pathogens

Not all bacteria carry the tatABC genes in their genome;[9] however, of those that do, there seems to be no discrimination between pathogens and nonpathogens. Despite that fact, some pathogenic bacteria such as Pseudomonas aeruginosa, Legionella pneumophila, Yersinia pseudotuberculosis, and E. coli O157:H7 rely on a functioning Tat pathway for full virulence in infection models. In addition, a number of exported virulence factors have been shown to rely on the Tat pathway. One such category of virulence factors are the phospholipase C enzymes, which have been shown to be Tat-exported in Pseudomonas aeruginosa, and thought to be Tat-exported in Mycobacterium tuberculosis.


  1. ^ Sargent, F.; Berks, B.C.; Palmer, T. (2006). "Pathfinders and trailblazers: a prokaryotic targeting system for transport of folded proteins". FEMS Microbiol. Lett. 254 (2): 198–207. doi:10.1111/j.1574-6968.2005.00049.x. PMID 16445746.
  2. ^ Carrie, Chris; Weißenberger, Stefan; Soll, Jürgen (2016-10-15). "Plant mitochondria contain the protein translocase subunits TatB and TatC". Journal of Cell Science. 129 (20): 3935–3947. doi:10.1242/jcs.190975. ISSN 0021-9533.
  3. ^ Bennewitz, Bationa; Sharma, Mayank; Tannert, Franzisca; Klösgen, Ralf Bernd (November 2020). "Dual targeting of TatA points to a chloroplast-like Tat pathway in plant mitochondria". Biochimica et Biophysica Acta (BBA) - Molecular Cell Research. 1867 (11): 118816. doi:10.1016/j.bbamcr.2020.118816.
  4. ^ Barnett JP, Eijlander RT, Kuipers OP, Robinson C (2008). "A minimal Tat system from a gram-positive organism: a bifunctional TatA subunit participates in discrete TatAC and TatA complexes". J. Biol. Chem. 283 (5): 2534–2542. doi:10.1074/jbc.M708134200. PMID 18029357.
  5. ^ Chaddock, A.M.; Mant, A.; Karnauchov, I.; Brink, S.; Herrmann, R.G.; Klösgen, R.B.; Robinson, C. (1995). "A new type of signal peptide: central role of a twin-arginine motif in transfer signals for the delta pH-dependent thylakoidal protein translocase". EMBO J. 14 (12): 2715–2722. doi:10.1002/j.1460-2075.1995.tb07272.x. PMC 398390. PMID 7796800.
  6. ^ Frielingsdorf, S.; Klösgen, R.B. (2007). "Prerequisites for Terminal Processing of Thylakoidal Tat Substrates". J. Biol. Chem. 282 (33): 24455–24462. doi:10.1074/jbc.M702630200. PMID 17581816.
  7. ^ Sargent F, Bogsch EG, Stanley NR, Wexler M, Robinson C, Berks BC, Palmer T (1998). "Overlapping functions of components of a bacterial Sec-independent protein export pathway". EMBO Journal. 17 (13): 3640–50. doi:10.1093/emboj/17.13.3640. PMC 1170700. PMID 9649434.
  8. ^ Gouffi K, Santini CL, Wu LF (August 2002). "Topology determination and functional analysis of the Escherichia coli TatC protein". FEBS Lett. 525 (1–3): 65–70. doi:10.1016/s0014-5793(02)03069-7. PMID 12163163.
  9. ^ Organism

This page is based on a Wikipedia article. The text is available under the Creative Commons Attribution/Share-Alike License.

This tab holds the annotation information that is stored in the Pfam database. As we move to using Wikipedia as our main source of annotation, the contents of this tab will be gradually replaced by the Wikipedia tab.

mttA/Hcf106 family Provide feedback

Members of this protein family are involved in a sec independent translocation mechanism. This pathway has been called the DeltapH pathway in chloroplasts [2]. Members of this family in E.coli are involved in export of redox proteins with a "twin arginine" leader motif [1].

Literature references

  1. Weiner JH, Bilous PT, Shaw GM, Lubitz SP, Frost L, Thomas GH, Cole JA, Turner RJ; , Cell 1998;93:93-101.: A novel and ubiquitous system for membrane targeting and secretion of cofactor-containing proteins. PUBMED:9546395 EPMC:9546395

  2. Settles AM, Yonetani A, Baron A, Bush DR, Cline K, Martienssen R; , Science 1997;278:1467-1470.: Sec-independent protein translocation by the maize Hcf106 protein. PUBMED:9367960 EPMC:9367960

Internal database links

External database links

This tab holds annotation information from the InterPro database.

InterPro entry IPR003369

Translocation of proteins across the two membranes of Gram-negative bacteria can be carried out via a number of routes. Most proteins marked for export carry a secretion signal at their N terminus, and are secreted by the general secretory pathway. The signal peptide is cleaved as they pass through the outer membrane. Other secretion systems include the type III system found in a select group of Gram-negative plant and animal pathogens, and the CagA system of Helicobacter pylori [ PUBMED:9649434 ].

In some bacterial species, however, there exists a system that operates independently of the Sec pathway [ PUBMED:10652088 ]. It selectively translocates periplasmic-bound molecules that are synthesised with, or are in close association with, "partner" proteins bearing an (S/T)RRXFLK twin arginine motif at the N terminus. The pathway is therefore termed the Twin-Arginine Translocation or TAT system. Surprisingly, the four components that make up the TAT system are structurally and mechanistically related to a pH-dependent import system in plant chloroplast thylakoid membranes [ PUBMED:10652088 ]. The gene products responsible for the Sec-independent pathway are called TatA, TatB, TatC and TatE.

This entry represents the related TatA, TatB and TatE proteins.

Gene Ontology

The mapping between Pfam and Gene Ontology is provided by InterPro. If you use this data please cite InterPro.

Domain organisation

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Curation and family details

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Seed source: Pfam-B_1826 (release 5.4)
Previous IDs: MttA_Hcf106;
Type: Family
Sequence Ontology: SO:0100021
Author: Bateman A
Number in seed: 11
Number in full: 13561
Average length of the domain: 70.00 aa
Average identity of full alignment: 25 %
Average coverage of the sequence by the domain: 67.20 %

HMM information View help on HMM parameters

HMM build commands:
build method: hmmbuild -o /dev/null HMM SEED
search method: hmmsearch -Z 61295632 -E 1000 --cpu 4 HMM pfamseq
Model details:
Parameter Sequence Domain
Gathering cut-off 21.0 21.0
Trusted cut-off 21.0 21.0
Noise cut-off 20.9 20.9
Model length: 53
Family (HMM) version: 19
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Species distribution

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Colour assignments

Archea Archea Eukaryota Eukaryota
Bacteria Bacteria Other sequences Other sequences
Viruses Viruses Unclassified Unclassified
Viroids Viroids Unclassified sequence Unclassified sequence


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For those sequences which have a structure in the Protein DataBank, we use the mapping between UniProt, PDB and Pfam coordinate systems from the PDBe group, to allow us to map Pfam domains onto UniProt sequences and three-dimensional protein structures. The table below shows the structures on which the TatA_B_E domain has been found. There are 15 instances of this domain found in the PDB. Note that there may be multiple copies of the domain in a single PDB structure, since many structures contain multiple copies of the same protein sequence.

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AlphaFold Structure Predictions

The list of proteins below match this family and have AlphaFold predicted structures. Click on the protein accession to view the predicted structure.

Protein Predicted structure External Information
A0A1D6GLJ8 View 3D Structure Click here
A0A1D6J5Z2 View 3D Structure Click here
A0KEG0 View 3D Structure Click here
A0L835 View 3D Structure Click here
A0LIM7 View 3D Structure Click here
A0QZ40 View 3D Structure Click here
A1AVW1 View 3D Structure Click here
A1BE06 View 3D Structure Click here
A1KAU9 View 3D Structure Click here
A1KAV0 View 3D Structure Click here
A1SAK1 View 3D Structure Click here
A1SRS0 View 3D Structure Click here
A1SRS1 View 3D Structure Click here
A1TAN7 View 3D Structure Click here
A1TL12 View 3D Structure Click here
A1TL13 View 3D Structure Click here
A1UFV8 View 3D Structure Click here
A1VK47 View 3D Structure Click here
A1VK48 View 3D Structure Click here
A1W450 View 3D Structure Click here
A1W451 View 3D Structure Click here
A1WFS5 View 3D Structure Click here
A1WFS6 View 3D Structure Click here
A1WW03 View 3D Structure Click here
A2SE14 View 3D Structure Click here
A2SE15 View 3D Structure Click here
A3N3S3 View 3D Structure Click here
A3PB74 View 3D Structure Click here
A3QIE4 View 3D Structure Click here
A3QIE5 View 3D Structure Click here
A4F8J0 View 3D Structure Click here
A4FBZ2 View 3D Structure Click here
A4G9I1 View 3D Structure Click here
A4G9I2 View 3D Structure Click here
A4SG03 View 3D Structure Click here
A4VGD9 View 3D Structure Click here
A4X752 View 3D Structure Click here
A4XPM2 View 3D Structure Click here
A4YV73 View 3D Structure Click here
A5EVU2 View 3D Structure Click here