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J. Bacteriol., 01 1996, 410-417, Vol 178, No. 2
E Roine, DN Nunn, L Paulin and M Romantschuk
Nonpiliated, phage phi 6-resistant mutants of Pseudomonas syringae pv.
phaseolicola were generated by Tn5 transposon mutagenesis. A P. syringae
pv. phaseolicola LR700 cosmid library was screened with Tn5- containing
EcoRI fragments cloned from nonpiliated mutants. The cosmid clone pVK253
complemented the nonpiliated mutant strain HB2.5. A 3.8-kb sequenced region
spanning the Tn5 insertion site contained four open reading frames. The
transposon-inactivated gene, designated pilP, is 525 bp long, potentially
encoding a 19.1-kDa protein precursor that contains a typical membrane
lipoprotein leader sequence. Generation of single mutations in each of the
three remaining complete open reading frames by marker exchange also
resulted in a nonpiliated phenotype. Expression of this gene region by the
T7 expression system in Escherichia coli resulted in four polypeptides of
approximately 39, 26, 23, and 18 kDa, in agreement with the sizes of the
open reading frames. The three genes upstream of pilP were designated pilM
(39 kDa), pilN (23 kDa), and pilO (26 kDa). The processing of the PilP
precursor into its mature form was shown to be inhibited by globomycin, a
specific inhibitor of signal peptidase II. The gene region identified shows
a high degree of homology to a gene region reported to be required for
Pseudomonas aeruginosa type IV pilus production.
Copyright © 1996, American Society for Microbiology
Characterization of genes required for pilus expression in Pseudomonas syringae pathovar phaseolicola
Department of Biosciences, University of Helsinki, Finland.
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