Bardaji, L., Añorga, M., Jackson, R. W., Martínez-Bilbao, A., Yanguas-Casás, N. and Murillo, J.
Miniature transposable sequences are frequently mobilized in the bacterial plant pathogen Pseudomonas syringae pv. phaseolicola.
PLoS ONE, 6 (10).
To link to this article DOI: 10.1371/journal.pone.0025773
Mobile genetic elements are widespread in Pseudomonas syringae, and often associate with virulence genes. Genome
reannotation of the model bean pathogen P. syringae pv. phaseolicola 1448A identified seventeen types of insertion
sequences and two miniature inverted-repeat transposable elements (MITEs) with a biased distribution, representing 2.8%
of the chromosome, 25.8% of the 132-kb virulence plasmid and 2.7% of the 52-kb plasmid. Employing an entrapment vector
containing sacB, we estimated that transposition frequency oscillated between 2.661025 and 1.161026, depending on the
clone, although it was stable for each clone after consecutive transfers in culture media. Transposition frequency was similar
for bacteria grown in rich or minimal media, and from cells recovered from compatible and incompatible plant hosts,
indicating that growth conditions do not influence transposition in strain 1448A. Most of the entrapped insertions
contained a full-length IS801 element, with the remaining insertions corresponding to sequences smaller than any
transposable element identified in strain 1448A, and collectively identified as miniature sequences. From these, fragments
of 229, 360 and 679-nt of the right end of IS801 ended in a consensus tetranucleotide and likely resulted from one-ended
transposition of IS801. An average 0.7% of the insertions analyzed consisted of IS801 carrying a fragment of variable size
from gene PSPPH_0008/PSPPH_0017, showing that IS801 can mobilize DNA in vivo. Retrospective analysis of complete
plasmids and genomes of P. syringae suggests, however, that most fragments of IS801 are likely the result of reorganizations
rather than one-ended transpositions, and that this element might preferentially contribute to genome flexibility by
generating homologous regions of recombination. A further miniature sequence previously found to affect host range
specificity and virulence, designated MITEPsy1 (100-nt), represented an average 2.4% of the total number of insertions
entrapped in sacB, demonstrating for the first time the mobilization of a MITE in bacteria.
|Date Deposited:||12 Oct 2011 12:49|
|Last Modified:||21 Oct 2013 07:13|
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