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Structural Biology & Bio-Informatics Division

Dr. Saumen Datta

Senior Scientist
PhD, Indian Institute of Science, Bangalore, India.
Postdoctoral associate, University of Connecticut, Connecticut, USA., 1998-1999
Postdoctoral associate, Washington University in St. Louis, Missouri, USA., 1999-2002
Assistant Research Scientist, John Hopkins University, Maryland, USA., 2002-2004
Quick Hire Fellow, Central Leather Research Institute, 2004-2006
Senior Research Fellow, University of Limerick, 2008

Contact - saumen_datta@iicb.res.in / saumen_datta@hotmail.com

Current Research Interest

Structural and functional investigations of important biological protein and protein complexes primarily using X-ray crystallography, SPR, CD, Cryo-electron microscopy, mass-spectrometry.

Current Research topic : Type III Secretion Systems

Many gram negative pathogenic bacteria use type three secretion systems (TTSS) to inject virulent proteins into the host cells through a specialized device called injectisome. After getting injected, these proteins disrupt cell’s cytoskeletal assembly and impair immune system; take control of the cell machinery for bacterial survival, replication and dissemination; and at the last promote cell death. These bacterial infestations are manifested by several diseases in animals and plants starting from mild gastroenteritis, dysentery, diarrhea to the acute and life-threatening typhoid fever, bubonic plague, and pneumonia. TTSS includes a complex macromolecular machinery (injectisomes), translocator and effector proteins, chaperone and other accessory proteins. Nearly 20 proteins, highly conserved among various bacterial species, constitute the injectisome. Structurally, the TTSS injectisome consists of two parts: a basal part which spans the inner and outer membrane of bacteria, and an extracellular needle that protrudes out of the bacterial surface. A central pore through the injectisome helps in the secretion of toxic effectors. Among secreted proteins, the effectors are highly variable but mostly act in similar ways, while translocators that form the tip of the needle complex are highly conserved. Chaperones have been classified into three categories depending on the nature of their substrates. Class I chaperone are related to effectors, Class II chaperones are used for translocators while the Class III chaperones act on needle proteins. TTSS chaperones are indispensable for their crucial roles in the assembly and functioning of injectisome and aids in translocation of various translocators and effector molecules through this injectisome.The virulent proteins do not have any identified secretory signal and the translocation of them directly facilitated by few dedicated chaperones. Biochemical, biophysical and structural investigations are being carried out to characterize all the virulent and other TTSS proteins but with limited success. Most of them are appeared to be bi-functional and manipulate eukaryotic cellular functions by structural mimicry of their host counterparts. Few three dimensional structures available to date substantially corroborate this view. The structural characterization of these proteins are therefore utmost important to clearly understand their hostile activity in side the host cell.

Research positions : Qualified NET/CSIR/ICMR/DST/DBT fellows interested in working on Biophysics and Biochemical properties of protein and protein complexes primarily using X-ray crystallography, SPR, CD, Cryo-electron microscopy, mass-spectrometry can directly contact or send their CV by email to me.

Names of the group members including regular staff with designation and research fellows:

Rakesh Chatterjee (SRF)
Pranab Halder (SRF)
Abhisek Mondal (NWP Project Fellow)
Basavraj Khanppavar (JRF)
Rajeev Kumar (JRF)
Arkaprabha Choudhury (JRF)
Ritapa Chaudhuri (DST project JRF)
Chittran Roy (DST project fellow)



Figure: A schematic reprenstation of TTSS; assembly of injectisome (A,B), assembly of translocators and pore formation at the host cell-membrane (C) and finally the routing of effectors into the host cell through injectisome (D).


Figure: Crystals of effector-chaperone complex (ExoT-SpcS) under polarized light (left panel). Structural overview of ExoT–SpcS, effector-chaperone complex: (A) frontal view and (B) side view of the chaperone binding domain of ExoT (green) wrapped around the SpcS dimer (right panel).

Some work on: Pantothenate synthetase pathway enzymes Phospho Pantoate Adenyl Transferase (PPAT) with its substrates and inhibitors.

Figure : Kinetics and crystal structural analysis of PPAT from Pseudomonas aeruginosa with AcCoA, a newly found allosteric inhibitor:

List of important Publications:

  1. Das A, Basu A, Mondal A, Datta S. Structural analysis of inter-genus complexes of V-antigen and its regulator and their stabilization by divalent metal ions. Eur Biophysics J. 2015 (in press) DOI :10.1007/s00249-015-1081-2
  2. Banerjee A, Dey S, Chakraborty A, Datta A, Basu A, Chakrabarti S, Datta S.Binding mode analysis of a major T3SS translocator protein PopB with its chaperone PcrH from Pseudomonas aeruginosa. Proteins. Dec;82(12):3273-85. doi: 10.1002/prot.24666
  3. Basu A, Das U, Dey S, Datta S. PcrG protects the two long helical oligomerization domains of PcrV, by an interaction mediated by the intramolecular coiled-coil region of PcrG. BMC Struct Biol. 2014 Jan 24;14(1):5. doi:10.1186/1472-6807-14-5.
  4. Dey S, Datta S. Interfacial residues of SpcS chaperone affects binding of effector toxin ExoT in Pseudomonas aeruginosa: novel insights from structural and computational studies. FEBS J. 2014 Jan 4. doi: 10.1111/febs.12704. [Epub ahead of print]
  5. Chatterjee R, Halder PK, Datta S. Identification and molecular characterization of YsaL (Ye3555): a novel negative regulator of YsaN ATPase in type three secretion system of enteropathogenic bacteria Yersinia enterocolitica. PLoS One. 2013 Oct 4;8(10):e75028
  6. Basu A, Chatterjee R, Datta S. YspC: A unique translocator exhibits structural alteration in the complex form with chaperone SycB. Protein J. 2012 Aug;31(6):487-98.
  7. Dey S, Basu A, Datta S. Characterization of molten globule PopB in absence and presence of its chaperone PcrH. Protein J. 2012 Jun;31(5):401-16.
  8. Basu A, Chatterjee R, Datta S. Expression, Purification, Structural and Functional Analysis of SycB: A Type Three Secretion Chaperone From Yersinia enterocolitica. Protein J. 2012 Jan;31(1):93-107.
  9. Chen ZW, Datta S, Dubois JL, Klinman JP, Mathews FS. Mutation at a strictly conserved, active site tyrosine in the copper amine oxidase leads to uncontrolled oxygenase activity. Biochemistry. 2010 Aug 31;49(34):7393-402.
  10. Larkin C, Datta S, Harley MJ, Anderson BJ, Ebie A, Hargreaves V, Schildbach JF. Inter- and intramolecular determinants of the specificity of single-stranded  DNA binding and cleavage by the F factor relaxase. Structure. 2005 Oct;13(10):1533-44.
  11. Aravinda S, Datta S, Shamala N, Balaram P. Hydrogen-bond lengths in polypeptide helices: no evidence for short hydrogen bonds. Angew Chem Int Ed Engl. 2004 Dec 10;43(48):6728-31.
  12. Datta S, Rathore RN, Vijayalakshmi S, Vasudev PG, Rao RB, Balaram P, Shamala N. Peptide helices with pendant cycloalkane rings. Characterization of conformations of 1-aminocyclooctane-1-carboxylic acid (Ac8c) residues in peptides. J Pept Sci. 2004 Mar;10(3):160-72.
  13. Datta S, Larkin C, Schildbach JF. Structural insights into single-stranded DNA binding and cleavage by F factor TraI. Structure. 2003 Nov;11(11):1369-79.
  14. Datta S, Ikeda T, Kano K, Mathews FS. Structure of the phenylhydrazine adduct  of the quinohemoprotein amine dehydrogenase from Paracoccus denitrificans at 1.7 A resolution. Acta Crystallogr D Biol Crystallogr. 2003 Sep;59(Pt 9):1551-6.
  15. Larkin C, Datta S, Nezami A, Dohm JA, Schildbach JF. Crystallization and preliminary X-ray characterization of the relaxase domain of F factor TraI. Acta Crystallogr D Biol Crystallogr. 2003 Aug;59(Pt 8):1514-6.
  16. Datta S, Mori Y, Takagi K, Kawaguchi K, Chen ZW, Okajima T, Kuroda S, Ikeda T, Kano K, Tanizawa K, Mathews FS. Structure of a quinohemoprotein amine dehydrogenase with an uncommon redox cofactor and highly unusual crosslinking.  Proc Natl Acad Sci U S A. 2001 Dec 4;98(25):14268-73.
  17. Datta S, Uma MV, Shamala N, Balaram P. Stereochemistry of Schellman Motifs in Peptides. Crystal Structure of a Hexapeptide with a C-terminus 6®1 Hydrogen Bond.   Biopolymers 1999 50; 13-22.
  18. Datta S, Shamala N, Banerjee A, Balaram P. Hydrogen bonding in peptide helices. Analysis of two independent helices in the crystal structure of a peptide Boc-Val-Ala-Leu-Aib-Val-Ala-Phe-OMe. J Pept Res. 1997 Jun;49(6):604-11.
  19. Datta S, Shamala N, Banerjee A, Balaram P. Conformational Variability of Gly-Gly Segments in Peptides. A Comparison of the Crystal Structures of an Acyclic Pentapeptide and an Octapeptide. Bioplolymers 1997: 41; 331-336.
  20. Datta S, Kaul R, Rao RB, Shamala N, Balaram P. Stereochemistry of Linking Segments in the Design of Helix-Helix Motifs in Peptides: Crystallographic Comparison of a Glycyl-Dipropyl-Glycyl Segment in a Tripeptide and in a 14 residue peptide.  J. Chem. Soc., Perkin Trans. 1997: 2; 1659-1664.
  21. Datta S, Shamala N, Banerjee A, Pramanik A, Bhattacharya S, Balaram P. Characterization of Helix Terminating Schellman Motifs in Peptides. Crystal Structure and Nuclear Overhausser Effect Analysis of a Synthetic Heptapeptide Helix.  J. Am. Chem. Soc. 1997, 119; 9246-9251.
  22. Banerjee A, Datta S, Pramanik A, Shamala N, Balaram P. Heterogeneity and Stability of Helical Conformation in Peptides: Crystallographic and NMR studies of a Model Heptapeptide.  J. Am. Chem. Soc. 1996, 118; 9477-9483.
  23. Datta S, Shamala N, Gurunath R, Balaram P. Observation of a mixed antiparallel and parallel beta-sheet motif in the crystal structure of Boc-Ala-Ile-Aib-OMe. Int J Pept Protein Res. 1996 Sep;48(3):209-14.


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