Ronen Marmorstein, B.S, MS., PhD.

Description of Research Expertise

Research Interests
Biochemical, biophysical and X-ray crystallographic techniques are employed to study the posttranslational modification of histones and other proteins and the misregulation of such modifications in cancer and metabolic disorders.

Key words: Transcription, Chromatin regulation, Protein-DNA recognition, Posttranslational modification, Tumor Suppressors, Viral oncoproteins, X-ray Crystallography, Enzymology, Structure, Biophysics.

Description of Research
The laboratory uses a broad range of molecular and biochemical research tools centered on X-ray crystal structure determination to understand the mechanism of macromolecular recognition and post-translational histone and protein modifications in the regulation of gene expression. The laboratory is particularly interested in gene regulatory proteins that are aberrantly regulated in cancer and age-related metabolic disorders such as type II diabetes and obesity, and the use of structure-based design strategies to develop protein-specific small-molecule compounds to treat such diseases.

Post-translational histone modification for gene regulation.
Histones package eukaryotic DNA into chromatin and are post-translationally modified to regulate gene expression in specific ways. We are studying the mechanism of action of these enzymes with a particular focus in histone acetyltransferases (HATs) and deacetylases (HDACs). We have determined the structures of various liganded forms of HATs and HDACs and have carried out biochemical and kinetic analysis to derive mechanistic details. We are continuing to probe the substrate specificity of these proteins and designing and characterizing inhibitors. We are also assembling relevant multiprotein HAT and HDAC complexes for biochemical and structural characterization. We are initiating similar structural and biochemical studies with other enzymes that covalently modify histones including kinases and deubiquitinases.

Sir2 enzymes and metabolic disorders.
Sir2 enzymes are NAD+-dependent histone and protein deactylases that have been implicated in the regulation of gene expression, cellular aging, adipogenesis and type II diabetes. We have determined the structure of the yeast Sir2 homologue, Hst2, alone and in complex with acetyl-lysine and NAD+-analogue substrates. Together with associated biochemical studies, these studies have provided insights into the mode of catalysis and substrate-specific recognition by this protein family. We are currently using our structure-function information to design Sir2 regulatory compounds that might have therapeutic application. We are also pursuing structures of the human Sir2 homologues in complex with their cognate protein substrates.

Tumor suppressors and viral oncoproteins.
We are pursuing biochemical and structural studies on the tumor suppressor proteins p18INK4c, pRb, p53 and p300/CBP, both alone and in complex with their relevant protein targets. The activity of pRb is inhibited by several known DNA viral oncoproteins, including human papillomavirus (HPV) E7, the etiological agent for cervical cancer, and Adenovirus (Ad) E1A. We have most recently characterized the binding properties of pRb to HPV-E7 and Ad-E1a and are now determining their structures both alone and in complex with pRb. Our goal for these studies is to derive functional and structural information that will lead to the design of small molecule compounds that may have clinical applications against cancer.

Protein-DNA recognition.
As a model to understand sequence-specific DNA recognition by transcriptional regulatory proteins, we are studying the structure and function of three families of DNA binding proteins, the fungal specific Zn2Cys6 binuclear cluster proteins, the higher eukaryotic Ets proteins and p53. We have determined several structures of these proteins either alone or in complex with their associated DNA targets and are continuing to use these proteins as a model to understand DNA recognition by protein and protein complexes. With regard to p53, we are studying its unique mode of DNA recognition and are developing structure-based strategies for the repair of tumor-derived p53 mutations.

Rotation Projects for 2006-2007
Rotation Students with an interest in incorporating the techniques of molecular biology, biochemistry, X-ray crystallography and enzymology to study areas of interest to the laboratory are encouraged to inquire by e-mail to Dr. Marmorstein to discuss specific rotation projects.

Lab personnel:
Postdoctoral Fellows
Santosh Hodawadekar
Keqin Li
Troy Messick
Yong Tang

Predoctoral Students
William Ho
Marc Holbert
Vinod Nayak
Mary Fitzgerald
Guoping Da
Xin Liu
Peng Xie
Manqing Hong
Michael Brent
Brandi Porter (Sanders)
Kim Malecka

Technicians
Damielle Snowflack
Mary Heil