Juan Carlos Slebe Tajmuch

Academic Training

  • Licenciado in Biochemistry, Universidad de Concepción, Chile, 1970.
  • Biochemist, Universidad de Chile, Chile, 1970.
  • Ph.D., Biology, Biochemistry Program, Universidad de Chile, Chile, 1985.
  • Research Associate, University of Notre Dame, USA, 1974-1976.

Scientific Interests

For several years, we have been developing a research line dedicated to studying the structure and function of fructose-1,6-bisphosphatase (FBPase), an allosteric enzyme that plays a predominant role in the regulation of gluconeogenesis. With this study, our main aim is to further knowledge of the mechanism of action of this enzyme, of the processes that govern folding and the specific association of subunits, of the intracellular localization of the enzyme and its interaction with other enzymes. In all, to better understand just how FBPase is regulated at a cellular level. We are also widening our investigation to include other enzymes of glucidic metabolism: fructose-1,6-bisphosphate aldolase (aldolases A and B; glycolysis/gluconeogenesis), phosphoenolpyruvate carboxykinase (PEPCK; gluconeogenesis), pyruvate kinase (PK; glycolysis) and glycogen synthase (GS; glycogenesis/glyconeogenesis).
We are interested in expression and regulation of the activities of these enzymes, as well as their subcellular localization and protein-protein interaction. To perform these studies, we are using a variety of biochemical, biophysical and cell and molecular biology methods, including enzyme kinetics, chemical modification, site-directed mutagenesis, fluorescence spectroscopy, immunohistochemistry, SPR, FRET and confocal microscopy. Results obtained with chemical modification have suggested that several amino acids are essential for regulation and catalysis of FBPase and have generated targets for site-directed mutagenesis. One very significant finding is our demonstration that FBPase and aldolase B, classically labelled as “soluble”, are found within the nucleus under certain cell metabolic conditions. So, translocation would be a new mechanism of regulation of gluconeogenesis and glyconeogenesis. ¿What is the mechanism of translocation? ¿Do these proteins have another function in the nucleus? These and other questions are part of our current research. We have also demonstrated that a key mechanism in kidney metabolic control is the compartmentalization of metabolic pathways in different nephron cells.

Both in vitro and in vivo studies of protein-protein interaction clearly show that the metabolic state of the cell modulates the specific interaction between hepatic FBPase and aldolase B, which would be a very interesting cellular mechanism for the regulation of substrate channelling in gluconeogenic and glyconeogenic pathways. A new model has been developed to explain regulation of these metabolic pathways; enzymes action at successive stages would be associated with multi-enzyme complexes, constituting units of metabolism (¿metabolons?). It is true that enzymes are essential components of all living beings and are vital for a large number of biological and biotechnological processes. However, under certain conditions, enzymes may become associated with genesis of a pathological process. Our studies may lead to the development of novel approaches for diagnosis and/or prevention of disturbances to carbohydrate metabolism. Given that Diabetes mellitus produces renal damage, diabetic nephropathy is the renal disease under study.

 

Relevant Publications

Ludwig, H.C., Pardo, F.N., Asenjo, J.L., Maureira, M.A., Yañez, A.J. & Slebe, J.C. (2007). “Unraveling Multistate Unfolding of Pig Kidney Fructose-1,6-bisphosphatase Using Single Tryptophan Mutants”. J. FEBS Journal (FEBS J), 274, 5337-5349 (2007).


Yáñez, A.J., Bustamante, X., Bertinat, R., Werner, E., Rauch, M.C., Concha, I. I.,  Reyes, J.G. & J.C. Slebe (2007). “Expression of key substrate cycle enzymes in rat spermatogenic cells: fructose-1,6-bisphosphatase and 6 phosphofructose 1-kinase”. J. Cell. Physiol, 212 (3), 807-816.


Yañez, A.J., Ludwig, H.C., Bertinat, R., Spichiger, C., Gatica, R., Berlien, G., León, O., Brito, M., Concha, I.I. &. Slebe, J.C. (2005). “Different involvement for aldolase isoenzymes in kidney glucose metabolism. Aldolase B but not aldolase A colocalizes and form a complex with fructose 1,6-bisphosphatase. J. Cell. Physiol. 202, 743-753.


Yañez, A.J., García-Rocha, M., Bertinat, R., Droppelmann, C., Concha, I.I., Guinovart, J.J. & Slebe, J.C. (2004). “Subcellular localization of liver FBPase is modulated by metabolic conditions”.FEBS Letters 577, 154-158.


Cárcamo, J.G., Yañez, A.J., Ludwig, H.C., León, O., Pinto, R.O., Reyes, A.M. & Slebe J.C. (2000). “The C1-C2 interface residue lysine 50 of pig kidney fructose 1,6-bisphosphatase has a crucial role in the cooperative signal transmission of the AMP inhibition.” European J. Biochem.. 267, 2242-2251.


Reyes, A.M., Burgos, M.E., Hubert, E. & Slebe, J.C. (1987). "Selective thiol group modification renders fructose-1,6-bisphosphatase insensitive to fructose 2,6-bisphosphate inhibition". J. Biol. Chem. 262, 8451-8454.