A Coxiella burnetti repeated DNA element resembling a bacterial insertion sequence

Abstract

A DNA fragment located on the 3' side of the CoxieUla burnetii htpAB operon was determined by Southern blotting to exist in approximately 19 copies in the Nine Mile I genome. The DNA sequences of this htpAB-associated repetitive element and two other independent copies were analyzed to determine the size and nature of the element. The three copies of the element were 1,450, 1,452, and 1,458 bp long, with less than 2% divergence among the three sequences. Several features characteristic of bacterial insertion sequences were discovered. These included a single significant open reading frame that would encode a 367-amino-acid polypeptide which was predicted to be highly basic, to have a DNA-binding helix-turn-helix motif, to have a leucine zipper motif, and to have homology to polypeptides found in several other bacterial insertion sequences. Identical 7-bp inverted repeats were found at the ends of all three copies of the element. However, duplications generated by many bacterial mobile elements in the recipient DNA during insertion events did not flank the inverted repeats of any of the three C. burnetii elements examined. A second pair of inverted repeats that flanked the open reading frame was also found in all three copies of the element. Most of the divergence among the three copies of the element occurred in the region between the two inverted repeat sequences in the 3' end of the element. Despite the sequence changes, all three copies of the element have retained significant dyad symmetry in this region.

Is Q Fever an emerging or re-emerging zoonosis?

“…In contrast to other similar intracellular pathogens, Chlamydia [157], Rickettsia [115], Mycobacterium [33], C. burnetii possesses 29 insertion sequence (IS) elements. There are 21 copies of a unique IS110-related isotype, named IS1111, 5 IS30 and 3 ISAs1 family elements, and 3 degenerate transposase genes of unknown lineage [63]. Among the strains, four plasmid types designated QpH1, QpRS, QpDV and one plasmid without designation derived from a chinese C. burnetii isolate have been described [60,70,88,112,163,172].…”

Association betweenCoxiella burnetii shedding in milkand subclinical mastitis in dairy cattle

“…Briefly, DNA from milk was isolated using the DNeasy Tissue kit (Qiagen, Valencia, CA, USA) according to the manufacturer's instructions. Isolated DNA samples were tested using primers and a probe targeting the repetitive transposonlike region (1S1111a) of the C. burnetii genome [12]. Real-time PCR was performed with an ABI Prism 7000 Sequence Detection System (Applied Biosystems, Foster City, CA, USA).…”

“…Template DNA • C for 60 s. A standard curve was constructed using a series of 10-fold dilutions of total genomic DNA (10 6 to 10 1 C. burnetii genome copies/mL) isolated from C. burnetii Nine Mile, phase II (RSA 493). DNase free water was used as the negative control [12].…”

Characterization of an IS-like element from Mycobacterium tuberculosis

“…It is possible that an exchange of genetic material between mycobacterial species and other genera has occurred several times as there exists another example of an IS-like element, IS900 of M . paratuberculosis, which might be reminiscent of such a horizontal gene transfer event (Green et al, 1989;Hoover et al, 1992).…”