Dr. Jacalyn M. Green

Professor of Biochemistry


Midwestern University
Chicago College of Osteopathic Medicine
College of Dental Medicine- Illinois
Department of Biochemistry
Science Hall 421-K
555 31st St.
Downers Grove, IL 60515


Office: (630) 515-6155
e-mail: jgreen@midwestern.edu

EDUCATION

B.S. Chemistry University of Dayton (Dayton, OH) 1982
Ph.D. Biological Chemistry The University of Michigan (Ann Arbor, MI)      1988

RESEARCH SUMMARY

Folic Acid Metabolism Folic acid is a water soluble vitamin that is biologically active in its reduced forms, which act as one-carbon carriers in the biosynthesis of DNA, RNA, and amino acids. Folic acid is synthesized in plants and bacteria, and is required by humans. The importance of this vitamin in support of cell division in both prokaryotes and eukaryotes has resulted in many clinical applications.  These include the development of antibiotics which target folate biosynthesis in bacteria, and chemotherapeutic drugs which target folate utilization in rapidly dividing cells.

Folate catabolism in bacteria. A primary focus of our laboratory is the investigation of  bacterial folate catabolism, using Escherichia coli as a model system.  Bacterial biosynthesis of folate is well understood, and has yielded many clinical applications in the form of antibiotics.  In contrast, folate catabolism has been much less studied. We study the abg operon of E. coli which encodes proteins involved in uptake and cleavage of folate catabolite p-aminobenzoyl-glutamate (PABA-GLU).  Our laboratory has demonstrated that transport protein AbgT imports PABA-GLU, and PABA-GLU hydrolase (PGH), an AbgA2AbgB2 hetero-tetramer, cleaves it into PABA and glutamate.  Divergently transcribed from the abg operon is the gene encoding the transcriptional regulator AbgR.  This operon is present only in E. coli and its close relatives, and there are intriguing patterns of differences in the sequences among these strains that suggest that the genes/proteins of the abg operon may play a role in determining the virulence of the most pathogenic members.  E. coli strains range in pathogenicity, ranging from the benign E. coli K12 strains to those causing urinary tract infections to those causing hemolytic uremic syndrome.  In addition, antibiotic resistance is a growing problem in medicine; any pathway that is important to the pathogen and absent in the human host offers a potential anti-bacterial target. 

Folic acid metabolism in head and neck squamous cell carcinoma.This project is in collaboration with Drs. Bruno Jham (CDMI) and Dr. Joanna Goral (CCOM, Anatomy).  Head and neck squamous cell carcinoma (HNSCC) is the sixth leading cause of death by cancer world-wide. Unfortunately, diagnosis is often made at advanced stages, resulting in a poor prognosis for patients.  Risk factors include use of tobacco products, alcohol consumption, and infection by human papillomavirus. The role of folate transport has not been well characterized in HNSCC.  

Research Projects

Project I: Characterization of the role of metal in p-aminobenzoyl-glutamate hydrolase (PGH)  PGH is composed of two subunits of AbgA and AbgB, respectively, and also requires manganese(II) for activity.  A continuing project is to characterize the role of metal in this enzyme, including the determination of how many manganese bind per subunit, and the relationship between metal-binding and quaternary structure.  Techniques include protein purification, enzyme assays, equilibrium dialysis, and electron paramagnetic resonance experiments (done in collaboration with Dr. Brian Bennett of Marquette University, Milwaukee, WI).

Project II: Characterization of folate transport protein expression in normal cadaveric tissues and pathological samples of head and neck squamous cell carcinoma.  Folate is important for rapidly dividing cells, yet its role in head and neck squamous cell carcinoma has not been well studied.  This project involves using antibodies for the three major folate transporters in humans:  folate receptor, reduced folate carrier, and the proton-coupled folate transporter. Immunohistochemistry will be performed on paraffin-embedded slides of normal and pathological tissues.  Results will be analyzed both for patterns of expression in various normal tissues (liver, kidney, small intestine, tongue) as well as for changes in expression in HNSCC (normal tissue versus cancer).  

Project III: Characterization of the DNA binding properties of AbgR.   Sequence analysis is consistent with identification of AbgR as a transcriptional regulator;   AbgR likely binds and regulates transcription of the operon including abgA, abgB, and abgT.  AbgR has been cloned and a purification protocol has been developed.  Further studies involve the identification of the DNA binding site for AbgR and identification of additional targets of regulation.

Selected publications on folate catabolism (for an expanded list of publications, click here)

  1. Comparison of Substrate Specificity of Escherichia coli p-Aminobenzoyl-glutamate Hydrolase with Pseudomonas Carboxypeptidase G. (2014)  Larimer, C.M., Slavnic, D., Pitstick, L.D., and Green, J.M. Advances in Enzyme Research, 2, 39-48. http://dx.doi.org/10.4236/aer.2014.21004 click here for full text
  2. Glucarpidase to combat toxic levels of methotrexate in patients.(2012) Green, J.M. Ther. Clin. Risk Manag. 8:403-13. doi: 10.2147/TCRM.S30135. Epub 2012 Nov 22. PMID: 23209370  click here for full text link
  3. Purification and characterization of the folate catabolic enzyme p-aminobenzoyl-glutamate hydrolase from Escherichia coli.(2010) Green. J.M., Hollandsworth. R., Pitstick. L., Carter. E.L.J. Bacteriol. 192(9):2407-13. doi: 10.1128/JB.01362-09. Epub 2010 Feb 26. PMID:20190044  click here for full text link
  4. Escherichia coli abg genes enable uptake and cleavage of the folate catabolite p-aminobenzoyl-glutamate. (2007) Carter, E.L., Jager. L., Gardner. L., Hall. C.C., Willis. S., Green. J.M. J Bacteriol. 189(9):3329-34. Epub 2007 Feb 16. PMID:17307853  click here for full text link
  5. Characterization of mutations that allow p-aminobenzoyl-glutamate utilization by Escherichia coli. (1998) Hussein, M.J., Green, J.M., Nichols, B.P.  J Bacteriol. 180(23):6260-8. PMID: 9829935, click here for full text link