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United States Department of Agriculture

Agricultural Research Service

Title: Evidence for Lateral Transfer to Brucellae: Characterization of a Locus with a Tn-Like Element (Tn 2020)

Authors
item Halling, Shirley
item Zuerner, Richard

Submitted to: Biochimica et Biophysica Acta
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: November 7, 2001
Publication Date: N/A

Interpretive Summary: The causative agent of bovine brucellosis is the bacterium Brucella abortus. Bacteria can enrich their metabolic potential and ability to cause disease by acquiring DNA from other closely related bacteria. Genes were identified and characterized from B. abortus that had the characteristics of foreign acquired genetic material. The results aid other scientists understanding the potential of Brucellae to acquire virulence related genes from other bacteria and how it causes disease. This impacts our knowledge of possible virulence factors of B. abortus that may be relevant to the development of new vaccines for wildlife to eradicate brucellosis.

Technical Abstract: A locus was discovered in the Brucella abortus that contains a novel transposon-like element designated Tn2020. Tn2020 is bounded by a copy an insertion sequence designated IS2020 and a truncated imperfect copy of IS2020 (tIS2020A). The truncated copy is immediately adjacent to a second copy of IS2020. These data are consistent with the locus having evolved by a complex rearrangement following the transposition of second copy of Tn2020. Analysis of the organization, orientation, and ORFs of IS2020 places it within the IS6 family. Four ORFs from Tn2020 were translated in vitro producing a potential transposase with an apparent molecular mass of 27.5kDa, and three polypeptides with apparent molecular masses of 71kDa, 22kDa, and 14kDa. A region near the amino terminus of the 71kda protein contains a potential DNA binding motif and resembles transcriptional regulatory proteins from several bacteria. Immediately 5' of Tn2020 are genes encoding ribosomal proteins L21, L27. This region also contains a 90-bp sequence that shares significant homology to a repetitive element with inverted repeats from the Sinorhizobium genome. Downstream of Tn2020 is an ORF encoding a protein having significant similarity to a hypothetical protein from Caulobacter. The locus is lower in G+C content from that of the genome. These data support the proposed taxonomic relationship of Brucellae to the alpha subdivision of proteobacteria and suggest that lateral transfer of genetic material has occurred.

Last Modified: 10/1/2014
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