Contact:
Phone:
(423) 439 5853
Fax:
(423) 439 4562
Mail:
Associate Professor & Assistant Chair
249 C Lamb Hall
Department of Health Sciences
College of Public Health
ETSU
Johnson City, TN 37614
Dr. Chakraborty's Web Site
RESEARCH INTERESTS
My major field of research involves investigation of ‘Iron transport systems’ in gram negative bacteria including E. coli, Pseudomonas and an agriculturally important Rhizobium leguminosarum. Iron is a vital element required by all microorganisms except Lactobacilli and Streptococcus sanguis. The ability to acquire iron in several pathogens has been related to their virulence. Some iron-transport systems also naturally transport antibiotics into the cell. Since iron is vital to the organism, iron-transport systems could either be blocked or exploited to deliver antibiotics efficiently into the cell to control pathogens’ growth inside the body of the host. Under iron-depleted conditions many gram-negative bacteria including several pathogens, express complex iron transport systems. Iron is vital element required by all living beings with very few exceptions in microorganisms as mentioned earlier. It is important to understand the molecular mechanism of iron transport particularly in pathogenic bacteria so that new ways of either delivering or designing drug to be delivered can be found out. Therefore, our focus is to investigate the molecular mechanism of iron in these bacteria. In Rhizobium leguminosarum, which fixes atmospheric nitrogen within the root nodules of leguminous plants, iron is an important component of its nitrogen fixing enzyme, nitrogenase. Understanding the iron transport system will help to understand the mechanism of iron acquisition by these bacteria. Following are the list of research projects currently going on in my research lab:
Students will have opportunities to learn many important techniques of Molecular biology (cloning, site directed mutagenesis), biochemistry (small molecule and protein purification using sophisticated equipment, ligand-receptor binding), bioinformatics and crystallography.
- Investigation of molecular mechanism of siderophore transport through outer membrane receptor proteins FepA and FhuA in E.coli. (NIH funded)
- Studies on iron transport systems of Rhizobium leguminosarum strains (Currently we are investigating three different strains of Rhizobia).
- Studies on the Iron transport systems of human pathogens, Pseudomonas aeruginosa and P. putida.
- Understanding the mechanism of iron acquisition in clinical isolates of Pseudomonas in order to design drug that can target iron acquisition systems to restrict growth of these organisms. (In collaboration with VA, ETSU)
- Understanding the mechanism of iron acquisition in clinical isolates of Methicillin resistant S. aureus (MRSA) in order to design drug that can target iron acquisition systems to restrict growth of these organisms. (In collaboration with Marshfield Clinic Research Foundation, affiliated to University of Wisconsin Medical Center, WI)
Recent Publications:
1. Susan K. Buchanan, Barbara S. Smith, Lalitha Venkatramani, Di Xia, Lothar Esser, Maya Palnitkar, Ranjan Chakraborty, Dick van der Helm, Johann Deisenhofer. (1999), Crystal Structure of the Outer membrane Active Transporter FepA from Escherichia coli. Nature (Structural Biology), 6(1), 56.
2. Dick van der Helm and Chakraborty, R. N. (2002): ‘Structures of Siderophore Receptors’., Ed: Winkelmann, G. : Microbial Transport Systems. Wiley-VCH Verleg GmbH, Weinheim, Germany., pp. 261-288.
3. Ferguson Andrew, Chakraborty R.N., Barbara Smith, Lothar Essar, Dick van der Helm and Johann Deisenhofer (2002) Structural basis of gating by the outer membrane transporter FecA. Science, 295, 1715-1719.
4. van der Helm D., Chakraborty, R., Ferguson A.D., Smith, B. S., Esser, L., and Deisenhofer, J. (2002) Bipartite gating in the outer membrane protein FecA. Biochem. Soc. Trans., 30, 708-710.
5. Chakraborty, R. N., Edward Lemke, Cao, Z., Klebba, P. E. and Dick van der Helm. (2003) Identification and Mutational Studies of Conserved Amino acids in the outer membrane receptor protein FepA, which affect Transport but not Binding of Ferric Enterobactin in Escherichia coli. BioMetals, 16, 507-518.
6. Storey, E.P., Little, J., Lowman, D., and R. Chakraborty (2006) Characterization of ‘Schizokinen’; a dihydroxamate siderophore produced by Rhizobium leguminosarum IARI 917. BioMetals, 19, 637-649.
7. Chakraborty, R., Storey, E.P., and Dick van der Helm (2007) Molecular mechanism of ferricsiderophore passage through the outer membrane receptor proteins of Escherichia coli. BioMetals, 20, 263-274.
8. Lopez, Claudia, Alice, A. F., Chakraborty, R. and J. H. Crosa (2007) Identification of amino acid residues required for ferric-anguibactin transport in the outer membrane receptor FatA of V. anguillarum. Microbiology,153, 570-584.