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Molecular and biochemical comparison of the 70-kDa heat shock proteins of Trypanosoma cruzi
An analysis of the genetic organization, regulated expression and biochemical properties of the cytoplasmic/nuclear (hsp70) and mitochondrial (mtp70) 70-kDa heat shock proteins of Trypanosoma cruzi is presented. The two proteins are encoded by tandemly arranged gene families that are located on diff...
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Published in: | The Journal of biological chemistry 1994-02, Vol.269 (5), p.3868-3874 |
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Main Authors: | , , , , , , |
Format: | Article |
Language: | English |
Subjects: | |
Citations: | Items that this one cites Items that cite this one |
Online Access: | Get full text |
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Summary: | An analysis of the genetic organization, regulated expression and biochemical properties of the cytoplasmic/nuclear (hsp70)
and mitochondrial (mtp70) 70-kDa heat shock proteins of Trypanosoma cruzi is presented. The two proteins are encoded by tandemly
arranged gene families that are located on different chromosomes. Both are mildly heat-inducible but have different optimal
temperatures for expression. During the switch from proliferation to differentiation that occurs during the growth of T. cruzi
in culture, the hsp70 level decreases dramatically while the mtp70 level falls only slightly. The subcellular locations of
the two proteins differ during heat shock. While mtp70 remains associated with the kinetoplast at all temperatures, hsp70
becomes more concentrated in the nucleus at higher temperatures. Biochemical analysis of hsp70 and mtp70 revealed both to
be potent ATPases. Each protein binds ATP with a Km of about 70 microM and hydrolyzes ATP with a kcat of about 100 min-1,
100 times greater than the kcat of human hsp70. The high ATPase activities of hsp70 and mtp70 are further stimulated by incubation
with peptides, suggesting that these trypanosome heat shock proteins have protein chaperone activity. Finally, mtp70, but
not hsp70, was found to possess autophosphorylation activity in vitro, a property that it shares with prokaryotic hsp70. These
findings demonstrate unique cellular and biochemical characteristics of T. cruzi mtp70 and hsp70 that suggest that they play
distinct physiologic roles in the biology of the cell. |
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ISSN: | 0021-9258 1083-351X |
DOI: | 10.1016/S0021-9258(17)41940-5 |