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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: We report that TamA and a closely related protein TamL are confined almost exclusively to Proteobacteria and Bacteroidetes/Chlorobi respectively, whereas TamB is widely distributed across the majority of Gram-negative bacterial lineages.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.Taken together, the structural and phylogenetic analyses suggest that the TAM likely evolved from an original combination of BamA and TamB, with a later gene duplication event of BamA, giving rise to an additional Omp85 sequence that evolved to be TamA in Proteobacteria and TamL in Bacteroidetes/Chlorobi.

View Article: PubMed Central - PubMed

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

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The distribution of TamA, TamB, TamL, and BamA. Percentages of all completed genomes of the respective Phyla, which encode for the indicated proteins, are shown by color shading: Blue indicates 0%, white indicates 50%, and red indicates 100% as indicated in the legend. The completed genomes of three organisms with outer membranes were found to lack BamA (Heinz and Lithgow 2014): Coxiella burnetii (strain CbuG_Q212) lacks BamA but encodes a TamA, and Helicobacter pylori (strain SouthAfrica7) and Helicobacter pylori (strain Gambia94/24) both lack any Omp85 proteins based on their genome data. The Coxiella strain encodes a TamB, whereas both Helicobacter strains encode an AsmA_TamB protein. Only Phyla (Classes for the Proteobacteria) with more than five taxa with completed proteomes according to UniProt are shown. For the Firmicutes, only the organisms with a Gram-negative like cell envelope are shown.
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evv097-F4: The distribution of TamA, TamB, TamL, and BamA. Percentages of all completed genomes of the respective Phyla, which encode for the indicated proteins, are shown by color shading: Blue indicates 0%, white indicates 50%, and red indicates 100% as indicated in the legend. The completed genomes of three organisms with outer membranes were found to lack BamA (Heinz and Lithgow 2014): Coxiella burnetii (strain CbuG_Q212) lacks BamA but encodes a TamA, and Helicobacter pylori (strain SouthAfrica7) and Helicobacter pylori (strain Gambia94/24) both lack any Omp85 proteins based on their genome data. The Coxiella strain encodes a TamB, whereas both Helicobacter strains encode an AsmA_TamB protein. Only Phyla (Classes for the Proteobacteria) with more than five taxa with completed proteomes according to UniProt are shown. For the Firmicutes, only the organisms with a Gram-negative like cell envelope are shown.

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 distribution of TamA, TamB, TamL, and BamA. Percentages of all completed genomes of the respective Phyla, which encode for the indicated proteins, are shown by color shading: Blue indicates 0%, white indicates 50%, and red indicates 100% as indicated in the legend. The completed genomes of three organisms with outer membranes were found to lack BamA (Heinz and Lithgow 2014): Coxiella burnetii (strain CbuG_Q212) lacks BamA but encodes a TamA, and Helicobacter pylori (strain SouthAfrica7) and Helicobacter pylori (strain Gambia94/24) both lack any Omp85 proteins based on their genome data. The Coxiella strain encodes a TamB, whereas both Helicobacter strains encode an AsmA_TamB protein. Only Phyla (Classes for the Proteobacteria) with more than five taxa with completed proteomes according to UniProt are shown. For the Firmicutes, only the organisms with a Gram-negative like cell envelope are shown.
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Related In: Results  -  Collection

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evv097-F4: The distribution of TamA, TamB, TamL, and BamA. Percentages of all completed genomes of the respective Phyla, which encode for the indicated proteins, are shown by color shading: Blue indicates 0%, white indicates 50%, and red indicates 100% as indicated in the legend. The completed genomes of three organisms with outer membranes were found to lack BamA (Heinz and Lithgow 2014): Coxiella burnetii (strain CbuG_Q212) lacks BamA but encodes a TamA, and Helicobacter pylori (strain SouthAfrica7) and Helicobacter pylori (strain Gambia94/24) both lack any Omp85 proteins based on their genome data. The Coxiella strain encodes a TamB, whereas both Helicobacter strains encode an AsmA_TamB protein. Only Phyla (Classes for the Proteobacteria) with more than five taxa with completed proteomes according to UniProt are shown. For the Firmicutes, only the organisms with a Gram-negative like cell envelope are shown.
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: We report that TamA and a closely related protein TamL are confined almost exclusively to Proteobacteria and Bacteroidetes/Chlorobi respectively, whereas TamB is widely distributed across the majority of Gram-negative bacterial lineages.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.Taken together, the structural and phylogenetic analyses suggest that the TAM likely evolved from an original combination of BamA and TamB, with a later gene duplication event of BamA, giving rise to an additional Omp85 sequence that evolved to be TamA in Proteobacteria and TamL in Bacteroidetes/Chlorobi.

View Article: PubMed Central - PubMed

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

Show MeSH
Related in: MedlinePlus