Transmission of Bartonella species from edoparasites to the mammalian
host involves adaptation to thermal and other forms of stress. in orde
r to better understand this process, the heat shock response of Barton
ella henselae and Bartonella quintana was studied. Cellular proteins s
ynthesized after shift to higher temperatures were intrinsically label
led with [S-35]methionine and analysed by gel electrophoresis and fluo
rography. The apparent molecular masses of three of the major heat sho
ck proteins produced by the two Bartonella species were virtually iden
tical, migrating at 70, 60 and 10 kDa. A fourth major shock protein wa
s larger in B. quintana (20 kDa) than in B. henselae (17 kDa). The max
imum heat shock response in B. quintana and B. henselae was observed a
t 39 degrees C and 42 degrees C, respectively. The groEL genes of both
Bartonella species were amplified, sequenced and compared to other kn
own groEL genes. The phylogenetic tree based on the groEL alignment pl
aces B. quintana and B. henselae in a monophyletic group with Bartonel
la bacilliformis. the deduced amino acid sequences of Bartonella GroEL
homologues contain signature sequences that are uniquely shared by me
mbers of the Gram-negative alpha-purple subdivision of bacteria, which
live within eukaryotic cells. Recombinant His(6)-GroEL fusion protein
s were expressed in Escherichia coli to generate specific rabbit antis
era. The GroEL antisera were used to confirm the identity of the 60 kD
a Bartonella heat shock protein. These studies provide a foundation fo
r evaluating the role of the heat shock response in the pathogenesis o
f Bartonella infection.