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Evolution of the Translocation and Assembly Module (TAM).

Heinz E, Selkrig J, Belousoff MJ, Lithgow T - Genome Biol Evol (2015)

Bottom Line: Bacterial outer membrane proteins require the beta-barrel assembly machinery (BAM) for their correct folding and function.An additional feature of the BAM is the translocation and assembly module (TAM), comprised TamA (an Omp85 family protein) and TamB.Several sequence characteristics were discovered to define the TamB protein family: A signal-anchor linkage to the inner membrane, beta-helical structure, conserved domain architecture and a C-terminal region that mimics outer membrane protein beta-strands.

View Article: PubMed Central - PubMed

Affiliation: Department of Microbiology, Monash University, Melbourne, Victoria, Australia.

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The sequence diversity of TamB. TamB sequences mostly cluster according to their taxonomic group as indicated by colors; (A) represents full-length TamB sequences, the displayed sequences of TamB and related proteins were reduced to identity 0.9, the edges represent all-against-all BLAST e values with a cutoff of 1e-5, and the network visualization shows a force-directed network without weight. (B) represents only the 50 most amino-terminal sequences of the same sequences as in (A); the edges represent an e value cutoff of 1e-1 and the visualization is force-directed without weight. Several exceptions indicated in (B) are discussed in the text.
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evv097-F5: The sequence diversity of TamB. TamB sequences mostly cluster according to their taxonomic group as indicated by colors; (A) represents full-length TamB sequences, the displayed sequences of TamB and related proteins were reduced to identity 0.9, the edges represent all-against-all BLAST e values with a cutoff of 1e-5, and the network visualization shows a force-directed network without weight. (B) represents only the 50 most amino-terminal sequences of the same sequences as in (A); the edges represent an e value cutoff of 1e-1 and the visualization is force-directed without weight. Several exceptions indicated in (B) are discussed in the text.

Mentions: A surprising result was the finding of such a broad distribution of TamB sequences, given the restriction of TamA proteins predominantly to the Proteobacteria (Heinz and Lithgow 2014). To interrogate the extent of codistribution of TamB and TamA, we generated a heatmap of all complete proteomes with a color gradient indicating the percentage of encoded respective combinations of proteins, irrespective of whether they are coencoded in an operon (fig. 4). This shows that TamB can be found in all bacterial Phyla with an outer membrane, with a few exceptions like the early-branching Phyla Thermotogae and Thermodesulfobacteria. It should be noted that the representation of TamB within any given Phylum is not complete, emphasizing that TamB does not have an essential function (fig. 4 and 5A).Fig. 4.—


Evolution of the Translocation and Assembly Module (TAM).

Heinz E, Selkrig J, Belousoff MJ, Lithgow T - Genome Biol Evol (2015)

The sequence diversity of TamB. TamB sequences mostly cluster according to their taxonomic group as indicated by colors; (A) represents full-length TamB sequences, the displayed sequences of TamB and related proteins were reduced to identity 0.9, the edges represent all-against-all BLAST e values with a cutoff of 1e-5, and the network visualization shows a force-directed network without weight. (B) represents only the 50 most amino-terminal sequences of the same sequences as in (A); the edges represent an e value cutoff of 1e-1 and the visualization is force-directed without weight. Several exceptions indicated in (B) are discussed in the text.
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Related In: Results  -  Collection

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getmorefigures.php?uid=PMC4494059&req=5

evv097-F5: The sequence diversity of TamB. TamB sequences mostly cluster according to their taxonomic group as indicated by colors; (A) represents full-length TamB sequences, the displayed sequences of TamB and related proteins were reduced to identity 0.9, the edges represent all-against-all BLAST e values with a cutoff of 1e-5, and the network visualization shows a force-directed network without weight. (B) represents only the 50 most amino-terminal sequences of the same sequences as in (A); the edges represent an e value cutoff of 1e-1 and the visualization is force-directed without weight. Several exceptions indicated in (B) are discussed in the text.
Mentions: A surprising result was the finding of such a broad distribution of TamB sequences, given the restriction of TamA proteins predominantly to the Proteobacteria (Heinz and Lithgow 2014). To interrogate the extent of codistribution of TamB and TamA, we generated a heatmap of all complete proteomes with a color gradient indicating the percentage of encoded respective combinations of proteins, irrespective of whether they are coencoded in an operon (fig. 4). This shows that TamB can be found in all bacterial Phyla with an outer membrane, with a few exceptions like the early-branching Phyla Thermotogae and Thermodesulfobacteria. It should be noted that the representation of TamB within any given Phylum is not complete, emphasizing that TamB does not have an essential function (fig. 4 and 5A).Fig. 4.—

Bottom Line: Bacterial outer membrane proteins require the beta-barrel assembly machinery (BAM) for their correct folding and function.An additional feature of the BAM is the translocation and assembly module (TAM), comprised TamA (an Omp85 family protein) and TamB.Several sequence characteristics were discovered to define the TamB protein family: A signal-anchor linkage to the inner membrane, beta-helical structure, conserved domain architecture and a C-terminal region that mimics outer membrane protein beta-strands.

View Article: PubMed Central - PubMed

Affiliation: Department of Microbiology, Monash University, Melbourne, Victoria, Australia.

Show MeSH
Related in: MedlinePlus