The contribution of Dr. Chatterji's group can be summarized as follows:

• They have mapped the active site of the enzyme RNA polymerase and their work has shown for the first time the molecular details of the action of the antibiotic rifampicin during inhibition of bacterial transcription.

• The conversion of the transcription complex from initiation to the elongation of RNA synthesis is thought to be the rate-determining step in the regulation of gene expression. Dr. Chatterji and his colleagues have worked out the energetics of such reaction and showed that DNA topology can alter such barrier in a significant way. In addition, they also deciphered the control mechanism of RNA synthesis in E. coli under stress condition.

• This group has recently carried out directed mutagenesis in an E. coli transcription factor, which showed a unique control in transcription regulation by domain-domain interaction between two segments of the protein.

• The direct interaction between the stringent factor ppGpp and E. coli RNA polymerase has been documented and probably this would form the basis of stringent control in E. coliunder stress condition.

• The action of anti-sigma factor AsiA on the regulation of gene expression has been successfully demonstrated by this group.

• Recently Dr. Chatterji along with his student worked on the folding pattern of a multi subunit enzyme like E. coli RNA polymerase and showed how one subunit of the complex acts as a chaperone.

• Dr. Chatterji and his group are working on stringent responses in Mycobacteria. They showed that under starvation, M. smegmatis produce ppGpp which may have implication on the survival of Mycobacteria in macrophages. Other protein under starvation which is upregulated in M. smegmatis, Dps is being studied and its X-ray crystal structure has been determined.

• They are currently working on the development of Mycobacterium smegmatis under nutritional starvation as a model system for latent M. tuberculosis. Latency of M. tuberculosis and their long term persistence in human host is the most challenging problem today. However, a suitable model for the latent M. tuberculosis is necessary and comparatively fast growing M. smegmatis under starvation serves the purpose. Towards this direction they are identifying new proteins which are over expressed under starvation by proteomics, analyzing cell surface of the pathogen and reconstituting the transcription system in vitro for M. smegmatis.

• This group has demonstrated the presence of a gene responsible for quorum sensing and synthesis of second messenger c-di-GMP in mycobacteria. They have also identified a new protein in mycobacteria which can rescue the inhibitory effect of rifampicin on transcription.

• In an entirely different line of work, they are also involved in generating a condensed DNA brush and follow their biological activity in order to mimic nuclei which they name as Artificial Nuclei. They have used simple chemistry to generate immobile DNA covalently linked with its extremities to polystyrene beads. Langmuir-Blodgett technique has been used by them to trap single molecule of RNA polymerase and AFM images for RNA polymerase-promoter complex have been recorded.