User:Jose Manuel Estevez

Contact Info


FCEyN-Universidad de Buenos Aires, Pab.II, Ciudad Universitaria, Intendente Güiraldes 2160 Buenos Aires C1428EGA, ARGENTINA
 * Jose M. Estevez
 * University of Buenos Aires
 * Institute of Physiology, Molecular Biology and Neurosciences (IFIByNE-CONICET)
 * email: jestevez@fbmc.fcen.uba.ar

Education

 * 2009-present, Asistant Researcher, CONICET-IFIBYNE-UBA, Argentina
 * 2008, Post Doc, UC Berkeley, USA.
 * 2005-2007, Post Doc, Stanford University, USA.
 * 2004, PhD. in Biology, University of Buenos Aires Argentina
 * 1998, Bachelor in Botany, University of La Plata, Argentina

Research interests
Glycoproteins rich in hydroxyproline (HRGPs) are only present in the cell walls of plants and green algae. HRGPs are grouped into arabinogalactan proteins (AGPs) and extensins based on the type and extent of glycosylation. The most important post-translational modifications in HRGPs are: (i) the conversion of some units of proline into 4-hydroxyproline by the action of 4-prolyl hydroxylases (P4Hs); (ii) glycosylation of the hydroxyproline units (O-glycosylation) with short chains of arabinosides (2-4 sugars, in extensins) or large arabinogalactans (in AGPs). O-glycosylation type defines the glycomodules responsable for their shape, size, stability, and biological function in HRGPs.

HRGPs are broadly implicated in all aspects of plant growth and development, including fertilization, differentiation and tissue organization, control of cell expansion, cell fate, apoptosis, responses to stress and pathogenesis. However, in view of the fact these macromolecules are highly complex, the function of each HRGP is yet to be defined, which has led to major efforts to determine the structure and function of a specific HRGP.

The Arabidopsis genome comprises 13 genes encoding putative P4Hs, key enzymes responsible for the biosynthesis of mature HRGPs, such as AGPs and extensins. Unfortunately, research on the specific biological function for each of these genes is in part hampered because of the lack of knowledge of the detailed structure of their putative substrates regarding post-translational modifications, namely proline-hydroxylation (a pre-requisite for O-glycosylation) and unknown individual glycan structures. The glycans in the protein backbone is thought to be essential for the interaction of HRGPs with other molecules during physiological events. Therefore, P4Hs are enzymes likely relevant to plant cell function because they define the O-glycosylation sites of their substrates through previous hydroxylation of certain proline units in the protein backbone. Very little is known about the extent of redundancy, cell type in which they are expressed and substrate specificity.

In order to try to clarify the mentioned unsolved issues, I am using:

(1) a genetic approach by generating PH4-mutants in order to determine the degree of functional redundancy. (2) a functional genomics approach: to assess endogenous expression of the P4Hs in planta. (3) a biochemical approach to achieve expression of P4Hs in E. coli (or another heterologous system) in order to purify and biochemically characterize the enzymatic activity in vitro.

The ultimate goals are to link the biological activity of P4Hs to a specifc HRGPs (AGP or extensin molecules) and to understand the biological functions of O-glycosylation on a single HRGP backbone.

In addition, since we have detected AGPs in cell walls from very simple organisms such as green algae (Estevez et al. 2008 a,b), we have started a deeper characterization of these AGPs in order to get an evolutionary perspective of these O-glycoproteins in groups that have arisen much before vascular plants.

Publications
Martone P. T., Navarro D., Stortz, C. A., Estevez J. M ..2010. Differences in polysaccharide structure between calcified and uncalcified segments in the articulated coralline Calliarthron cheilosporioides (Corallinales, Rhodophyta). In press. J. Phycol. IF 2.88.

Fernandez P. V., Ciancia M,, Estevez, J. M. 2010. Cell wall polymers arrangements in the coenocitic seaweed Codium vermilara. In Press. J. Phycol. IF 2.88.

Sánchez-Rodríguez,C., Estévez J. M., F. Llorente, C. Hernández-Blanco, I. Pagán, M. Berrocal, Y. Marco, S.Somerville, and A. Molina. 2009. The ERECTA receptor-like kinase regulates cell wall-mediated resistance to pathogens in Arabidopsis thaliana. Molecular Plant Microbe Interaction. 22(8):953–963. IF 4.22.

Martone P. T.*, Estevez J. M. *, F. Lu, K. Ruel, M. W. Denny, C. Somerville, J. Ralph. 2009. Discovery of lignin in seaweed reveals convergent evolution of cell wall architecture. Current Biology. 19 (2): 169-175. (Seleccionado por Faculty 1000 Biology). IF 10.53.

Estevez J. M., L. Kasulin, P. V. Fernández, P. Dupree, M. Ciancia. 2009. Chemical and in situ characterization of macromolecular components of the complex cell walls from the coenocitic green alga Codium fragile. Glycobiology 19(3): 212-222. IF 4.44.

Estevez, J. M., P. Leonardi, J. Alberghina 2008. Cell wall carbohydrate-epitopes in the green algae Oedogonium bharuchae f. minor (Oedogoniales, Chlorophyta). J. Phycol. 44 (5): 1257-1268. IF 2.82. Estevez, J. M. ; Ciancia, M. & A. Cerezo. 2008. The system of sulfated galactans from the red seaweed Gymnogongrus torulosus (phyllophoraceae, rhodophyta). Location and structural analysis. Carbohydrate Polymers. Carbohydr. Polymers.73: 594-605. IF 2.64.

Ciancia, M, I. Quintana, M. I. Vizcargüénaga, L. Kasulin, A. de Dios, Estevez J. M. and A. S. Cerezo. 2007. Polysaccharides from the green seaweeds Codium fragile and C. vermilara with controversial effects on hemostasis. Int. J. of Biol. Macromol. 41 (5): 641-649. IF 1.86.

Estevez, J. M. & C. Somerville. 2006. Tetracystein-FIAsH-based approach to visualized synthetic hydroxyproline rich-olipeptide with AGP-motif expressed in Arabidopsis and Tobacco. Biotechniques. 41 (5), 569-572. IF 2.33

Estevez, J. M. ; Kiesliszewski M. J. & C. Somerville. 2006. Characterization of hydroxyproline rich oligopeptides with AGP- and extensin-motifs expressed in Arabidospsis: posttranslational modifications, in situ localization and phenotypic effects. Plant Physiology. 142, 458–470. IF 6.11.