Genes for the Major Structural Components of Thermotogales Species' Togas Revealed by Proteomic and Evolutionary Analyses of OmpA and OmpB Homologs
- Univ. of Connecticut, Storrs, CT (United States)
- Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
The unifying structural characteristic of members of the bacterial order Thermotogales is an unusual cell envelope that includes a loose-fitting sheath around each cell, often called a toga. Only two toga-associated structural proteins have been identified in Thermotoga maritima: the anchor protein OmpA1 (previously termed Ompα) and the porin OmpB (previously termed Ompβ). The gene encoding OmpA (ompA1) was assigned in the genome sequence to TM0477, but because no peptide sequence was available for OmpB, its gene (ompB) was not annotated. Here we identify the ompB gene as TM0476, determined by LC/MS/MS analysis of the native OmpB protein purified from T. maritima cells. The purified OmpB had β-sheet secondary structure as determined by circular dichroism. Analysis of the sequence of ompB product shows it has porin characteristics including a carboxy terminus anchoring motif and a porin-specific amino acid composition. Orthologs of ompB were found in the genomes of some, but not all, Thermotogales. Those without orthologs have putative analogs. Phylogenetic analyses of OmpA1 revealed that each species of the Thermotogales has one to three OmpA homologs. T. maritima has two OmpA homologs, encoded by ompA1(TM0477) and ompA2 (TM1729), both of which were found in the toga protein-enriched cell extracts. These annotations of the genes encoding toga structural proteins will guide future examinations of the structure and function of this unusual lineage-defining cell sheath.
- Research Organization:
- Pacific Northwest National Lab. (PNNL), Richland, WA (United States). Environmental Molecular Sciences Lab. (EMSL)
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- AC05-76RL01830
- OSTI ID:
- 1060129
- Report Number(s):
- PNNL-SA-84820; 39965; KP1704020
- Journal Information:
- PLoS ONE, Vol. 7, Issue 6; ISSN 1932-6203
- Publisher:
- Public Library of Science
- Country of Publication:
- United States
- Language:
- English
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