Click here to read about my research.

I am currently characterizing a protein that we identified in our yeast two-hybrid screens and that specifically interacts with the bHLH of R. This protein contains an ENT domain and an Agenet domain which can be diagnostic of a role in chromatin remodeling. My current experiments aim to understand the function of this protein and to ascertain if the regulation of the anthocyanin biosynthetic genes occurs also at the level of chromatin remodeling.

 

Personal Paragraph

I am a second year graduate student in the Ohio State Biochemistry Program (OSBP) .

This interdisciplinary program has given me the opportunity to enrich my graduate school experience through its research program diversity and the opportunity to participate in activities such as hosting seminars and serving in some of the OSBP Standing Committees.

I am currently in Erich Grotewold’s lab researching the combinatorial control of gene transcription using the flavonoid biosynthetic pathway in maize as our system.

There are many advantages to look at transcription in this system: a) it’s a very well characterized pathway in plants, both biochemically and at the regulatory level; b) there is a wealth of genetic data rivaled by few other eukaryotic systems; c) phenotypes are easy to score (accumulation of pigments); and d) it provides an ideal system to study the family of transcription factors we are interested in: the Myb domain proteins.

This family of transcription factors has expanded dramatically in the plants, which suggests that they control plant specific functions as it has been demonstrated in the few cases where the function of these proteins has been unveiled. We are taking advantage of the fact that there are two Myb genes controlling different branches of the pathway: P controls the biosynthesis of phlobaphenes while C1 controls the accumulation of anthocyanins. In spite of the fact that these two proteins share more than 70% identity in the Myb domain, they clearly have different regulatory specificity.

In addition, C1 cannot function in the absence of the bHLH protein R. We now know that R plays a key role in determining the biological specificity of C1. In addition, we have unveiled two roles for R: it is an essential coactivator of C1 and it also enhances transcriptional activation by directly binding or by recruiting a second binding factor to the are , a cis element present in all the anthocyanin biosynthetic genes.

I am presently trying to understand how R achieves these two functions. We are taking a variety of approaches to answer these questions which range from classical genetics, to molecular biology and biochemistry, to bioinformatics.

 

Publications

Hernandez, J. M., Sainz B. M., Chandler V. L., and Grotewold E. Mechanisms of cooperation between R2R3 Myb protein C1 and HLH co-activator R. 2002 Manuscript in preparation.

Smialek, J., J. M. Hernandez and E. Grotewold. The C-terminal domain of the maize P gene has a putative activation domain. 2001. MNL 75:18

Grotewold, E., M. B. Sainz. L. Tagliani, J. M. Hernandez, B. Bowen, and V. L. Chandler. Identification of residues in the Myb domain of maize C1 that specify the interaction with the bHLH cofactor R. 2000. PNAS, 97:13579-13584.

Hernandez, J. M., Pizzirusso M., and E. Grotewold. The maize MP1 gene encodes a WD-repeat protein similar to An11 and TTG. 2000. MNL 74:24

Hernandez J. M., Baker SH, Lorbach SC, Shively JM, Tabita FR. Deduced amino acid sequence, functional expression, and unique enzymatic properties of the form I and form II ribulose bisphosphate carboxylase/oxygenase from the chemoautotrophic bacterium Thiobacillus denitrificans. 1996. J Bacteriol. 178(2):347-56

Hernandez, J. M., Heine G., Irani N.G., Feller A., Kim M., Matulnik T. Chandler V. L., and Grotewold E. Different Mechanisms Participate in the R-Dependent Activity of the R2R3 MYB Transcription Factor C1. JBC 2004 Accepted.

Heine, G.F., Hernandez J.M., and Grotewold E. Two Cysteines in Plant R2R3 MYB Domains Participate in REDOX-dependent DNA Binding. JBC 2004 279:37878

Rangarajan S., Raj S., Hernandez J.M., Grotewold E., Gopalan V. RNase P as a tool for disruption of gene expression in maize cells. Biochem J. 2004 380:611

Henry I. M., Wilkinson M.D., Hernandez, J. M., Schwarz-Sommer Z., Grotewold E., and Mandoli D.F. Comparison of ESTs from Juvenile and Adult Phases of the Giant Unicellular Green Alga Acetabularia acetabulum. BMC Plant Biology 2004, 4:3

Irani, N., Hernandez, J.M., and Grotewold, E. (2003) Regulation of anthocyanin pigmentation. In Recent. Adv. Phytochem.

 

Meetings and Presentations

Hernandez, J. M. Irani, N.G., and Grotewold E. Coactivator dependent and independent transcription of flavonoid genes. Maize Genetics Conference. Orlando, Florida. 2002.

Hernandez, J. M. Irani, N.G., and Grotewold E. Coactivator dependent and independent transcription of flavonoid genes. Poster # 110. Maize Genetics Conference. Orlando, Florida. 2002.

Hernandez, J. M. Irani, N.G., and Grotewold E Regulatory Specificity of R2R3 Myb Transcription Factors. Overhead Poster Session I. American Society of Plant Biologists Meeting. Providence Rhode Island. 2001 Link

Hernandez, J. M. Irani, N.G., and Grotewold E. Regulatory Specificity of R2R3 Myb Transcription Factors. Poster #675. American Society of Plant Biologists Meeting. Providence Rhode Island. 2001 Link

Hernandez, J. M., Grotewold, E. Gordon Conference Molecular Genetics. New London Connecticut 2000.

Hernandez, J. M., Pizzirusso M., Sosa, G. M. and E. Grotewold Characterization of a maize gene encoding a conserved WD40 protein. Poster #104. Maize Genetics Conference. Lake Geneva, Wisconsin. 1999.

Hernandez, J. M., Heine G., and Grotewold E. Combinatorial transcriptional regulation of the maize flavonoid pathway and the dual function of the HLH cofactor R. ASBMB-IUBMB Meeting. Boston, Massachusetts. 2004.

J. Marcela Hernandez, Min-Gab Kim, Vicki L. Chandler, and Erich Grotewold. Transcriptional regulation of the flavonoid biosynthetic pathway: the dual role of the HLH coactivator R/B. Maize Genetics Conference. Lake Geneva, Wisconsin. 2003.

Hernandez J.M. Lockwood R.D., Mathews N. Szalma S.J. McMullen M.D., Grotewold E. Dissection of plant promoter function in vivo. Maize Genetics Conference. Lake Geneva, Wisconsin. 2003.

Hernandez J.M. Lockwood R.D., Mathews N. Szalma S.J. McMullen M.D., Grotewold E. Dissection of plant promoter function in vivo. Systems Biology: Genomic Approaches to transcriptional regulation. Cold Spring Harbor, New York. 2003.