1S801 is a transposable element isolated from Pseudomonas syringae pathovar
(pv.) phaseolicola, the causal agent of halo blight of bean. Fragments of the element are
present in multiple copies on an indigenous plasmid, pMMC7105, of strain LR781, and
have been implicated as sites of homologous recombination leading to imprecise
excision of the chromosomally integrated form of the plasmid. The element, which has
been completely sequenced, is 1512 base pairs in length and is unusual among
transposable elements in that it does not have direct or inverted repeats in its termini.
The terminal regions of the element were uncoupled from the two major open reading
frames, and trans-acting activity of the putative transposase was demonstrated in
Escherichia coli (recA). An alignment of the sequences of thirteen insertions defined
the precise borders of the element, and demonstrated that it does not duplicate its targets
upon insertion. The target specificity of IS801 is similar to, but more degenerate than,
the target specificity of two transposable elements to which it is closely related, IS91
and IS1294. The consensus derived from the aligned target sequences is G/C-A/G-A-C/G, and the target tetramer is found immediately adjacent to the right terminus of the
element upon transposition. IS91 was demonstrated to mobilize 1S801, but not with the
specificity characteristic of 1S801. The structure of 1S801 and the characteristics of
IS91-activated transposition of 1S801 are discussed in light of a proposed model for
IS91 transposition, and it is suggested that 1S801 could have been derived from IS91 by
a modification of its left end. Remnants of IS801 are present near avirulence genes of
various P. syringae pathovars, suggesting that the element has been involved in genetic
rearrangements in the vicinity of these loci. / Graduation date: 1996
| Identifer | oai:union.ndltd.org:ORGSU/oai:ir.library.oregonstate.edu:1957/34682 |
| Date | 11 August 1995 |
| Creators | Richter, Grace Yukiko |
| Contributors | Mills, Dallice |
| Source Sets | Oregon State University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis/Dissertation |
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