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Infect. Immun., 05 1996, 1736-1743, Vol 64, No. 5
RG Cluss, AS Goel, HL Rehm, JG Schoenecker and JT Boothby
The synthesis and turnover of heat shock proteins (Hsps) by Borrelia
burgdorferi, the Lyme disease spirochete, was investigated by radiolabeling
of whole spirochetes and spheroplasts, comparison of one- and
two-dimensional sodium dodecyl sulfate-polyacrylamide gel electrophoresis,
and use of immunochemistry. The approximately 72-kDa DnaK homolog and three
additional Hsps of 39, 27, and 21 kDa increased in amount by 3- to 15-fold
between 2 and 6 h following temperature upshift from 28 to 39 degrees C.
Temperature downshift experiments following the transfer of spirochetes
from 40 to 28 degrees C showed that within 15 to 30 min, synthesis of most
of the major Hsps returned to levels seen in spirochetes statically
maintained at the lower temperature. Spheroplasts of B. burgdorferi
produced by treatment with EDTA and lysozyme were radiolabeled, and
specific Hsps were localized to either the cytoplasm or membrane fraction.
Further analysis by two- dimensional electrophoresis demonstrated three
constitutively expressed DnaK isoforms with pIs near 5.5. A pattern
suggestive of DnaK degradation was observed following recovery from heat
shock but not in spirochetes maintained entirely at a low temperature. Some
of these putative degradation products were recognized by monoclonal
antibodies directed against the B. burgdorferi DnaK protein. These data
suggest that following a period of peak synthesis, DnaK is actively
degraded as the spirochete reestablishes its metabolic thermometer. These
findings provide a new interpretation of previous work suggesting that 10
to 15 B. burgdorferi polypeptides, including DnaK have a common epitope.
Copyright © 1996, American Society for Microbiology
Coordinate synthesis and turnover of heat shock proteins in Borrelia burgdorferi: degradation of DnaK during recovery from heat shock
Department of Chemistry and Biochemistry, Middlebury College, Vermont 05753, USA. cluss@middlebury.edu
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