Isomerase-Independent Chaperone Function of Cyclophilin Ensures Aggregation Prevention of Adenosine Kinase Both in Vitro and under in ViVo Conditions
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Isomerase-Independent Chaperone Function of Cyclophilin Ensures Aggregation
Prevention of Adenosine Kinase Both in Vitro and under in ViVo Conditions
Datta, Alok K
Infectious Diseases and Immunology
Using inactive aggregates of adenosine kinase (AdK) from Leishmania donoVani as the model
substrate, we recently demonstrated that a cyclophilin (LdCyP) from the same source in an isomeraseindependent
fashion reactivated the enzyme in Vitro by disaggregating its inactive oligomers [Chakraborty
et al. (2002) J. Biol. Chem. 277, 47451-47460]. Besides disrupting preformed aggregates, LdCyP also
prevents reaggregation of the newly formed active protein that is generated after productive refolding
from its urea-denatured state. To investigate possible physiological implications of such phenomena, a
unique expression system that simultaneously induces both AdK and LdCyP in naturally AdK-deficient
Escherichia coli, was developed. Both in Vitro and in ViVo experiments revealed that oligomerization is
an inherent property of this particular enzyme. In vivo protein cross-linking studies, activity determination
analysis and Ado phosphorylation experiments carried out in cells coexpressing both the proteins
unequivocally demonstrated that, similar to the phenomena observed in Vitro, aggregates of the enzyme
formed in ViVo are able to interact with both LdCyP and its N-terminal truncated form (N22-88DEL LdCyP)
in a crowded intracellular environment, resulting in aggregation prevention and reactivation of the enzyme.
Our results indicate that the isomerase-independent chaperone function of LdCyP, detected in Vitro,
participates in ViVo as well to keep aggregation-prone proteins in a monomeric state. Furthermore, analogous
to yeast/bacterial two-hybrid systems, development of this simple coexpression system may help in the
confirmation of interaction of two proteins under simulated in ViVo conditions.
Chakraborty, Anutosh and Sen, Banibrata and Datta, Rupak and Datta, Alok K (2004) Isomerase-Independent Chaperone Function of Cyclophilin Ensures Aggregation Prevention of Adenosine Kinase Both in Vitro and under in ViVo Conditions. Biochemistry , 43 (37). pp. 11862-11872.