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Infect. Immun., 05 1997, 1824-1829, Vol 65, No. 5
M Ericsson, I Golovliov, G Sandstrom, A Tarnvik and A Sjostedt
The groE operon of Francisella tularensis LVS, encoding the heat shock
proteins chaperone-10 (Cpn10) and Cpn60, was sequenced and characterized,
and the T-cell response of LVS-vaccinated individuals to the two proteins
and the third major chaperone, Ft-DnaK, was assayed. The cpn10 and cpn60
genes were amplified by PCR with degenerate oligonucleotides derived from
the N-terminal sequence of the two proteins. The sequence analysis revealed
the expected two open reading frames, encoding proteins with estimated Mrs
of 10,300 and 57,400. The deduced amino acid sequences closely resembled
Cpn10 and Cpn60 proteins of other prokaryotes. The genes constituted a
bicistronic operon, the cpn10 gene preceding the cpn60 gene. Upstream of
the cpn10 gene, an inverted repeat and motifs similar to -35 and -10
sequences of sigma70- dependent but not of sigma32-dependent promoters of
Escherichia coli were found. The inverted repeat of the operon resembled
so-called hairpin loops identified in other characterized prokaryotic groE
operons lacking sigma32-dependent promoters. Primer extension analysis
disclosed one and the same transcription start, irrespective of the
presence or absence of heat or oxidative stress. After separation of
lysates of the F. tularensis LVS organism by two-dimensional gel
electrophoresis, DnaK, Cpn60, and Cpn10 were extracted and used as antigens
in T-cell tests. When compared to those from nonvaccinated individuals, T
cells from individuals previously vaccinated with live F. tularensis LVS
showed an increased proliferative response to DnaK and Cpn60 but not to
Cpn10. The present data will facilitate further studies of the involvement
of the heat shock proteins in protective immunity to tularemia.
Copyright © 1997, American Society for Microbiology
Characterization of the nucleotide sequence of the groE operon encoding heat shock proteins chaperone-60 and -10 of Francisella tularensis and determination of the T-cell response to the proteins in individuals vaccinated with F. tularensis
Department of Infectious Diseases, Umea University, Sweden.
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