Our laboratory’s research goal is to unravel the structural basis of the functioning of large macromolecular complexes, and thereby, to identify potential drug targets. We have been applying a multidisciplinary approach of molecular biology, biochemistry, cryo- electron microscopy (cryo- EM) and X-ray crystallography and bioinformatics. The Cryo- EM is emerging a powerful research technique, with the recent advancement in electron detection technology and improved image processing algorithms, now, it is possible to achieve atomic resolution structure of macromolecular complexes. Following are the ongoing research projects.

1. Ribosome biogenesis
   

   Ribosomes are ribonucleoprotein complexes of mega Dalton (mDa) sizes and are responsible for protein synthesis in the cell. Formation of functional ribosome involves series of processes, i.e., synthesis, processing and modification of both rRNA and r-proteins and assembling the components. Each ribosome is composed of two subunits, large subunit (LSU) and small subunit (SSU). In prokaryote, LSU contains 33 ribosomal proteins (r-proteins) and 23S rRNA and 5S rRNA, whereas, SSU contains 21 r-proteins and 16S rRNA. Altogether, prokaryotic ribosome is composed of 44 r-proteins and 3 rRNSs. The assembly factors; RNA Chaperon, RNA helicase, ribosome-dependent GTPases are involved in proper ribosome assembly process, as shown mostly by genetic studies. One of our research focus is to understand structural basis of ribosome biogenesis and assembly.

2. Protein synthesis in pathogenic organisms
   

   The protein synthesis, translation of the genetic code into the amino acid, have been an attractive drug target, nearly 40% of antibiotics targets different steps of protein synthesis in bacteria. However, protein synthesis in pathogenic organisms is poorly understood. Our focus is on the structural aspects of protein synthesis in (a) the Plasmodium falciparum an intracellular obligate human parasite that causes the most lethal form of malaria; (b) the Mycobacterium tuberculosis (MTb) that causes tuberculosis, and to find out new drug targets and therapeutics.
   

   1. Protein synthesis in Plasmodium falciparum
      

      Every year, malaria has killed nearly half a million peoples worldwide, with the majority of victims being children under 5 years of age. Owing to the emergence of parasite resistance to front-line drugs, there is an urgent need to find new antimalarial drug targets. The P. falciparum has three sites of protein synthesis the cytoplasmic ribosome and two organellar ribosomes, of bacterial origin, reside inside the mitochondria and another inside, a non-photosynthetic relict plastid, the apicoplast. The organellar ribosomes are attractive antimalarial drug targets because of their prokaryotic origin. An integrated approach is being applied to understand the structural aspects of protein synthesis in organallar ribosomes with specific aims to solve the structures of mitochondrial and apicoplast ribosomes, and their functional complexes trapped at different states of protein synthesis.
      

   2. Dormancy in Mycobacteria
      

      Tuberculosis (Tb) remains a major health threat to the human race. Mtb has emerged with drug resistant strains towards currently used drugs. Situation in India is more alarming by recent emergence of a total drug-resistant Tb strain. Hence, a better understanding of pathogen’s life cycle is vital to facilitate the finding of new targets. The MTb possesses a unique mechanism to establish a latent tuberculosis infection (LTBI), the dormancy state, capable of its long persistence in the host, even in the presence of functional host immune response. An estimated one third of the world’s population has LTBI. The dormancy survival regulon (DosR regulon) encodes 48 genes that appear to play crucial roles in dormancy. Our aim is to better understand the life cycle of the Mtb pathogen in its dormancy sate, by illustrating the role of all 48 genes that are expressed during pathogen’s dormancy.
      

3. Methods for cryo- EM
   

   One of the major bottleneck to achieve high resolution in cryo- EM is to get evenly distributions of particle with optimum ice thickness on the cryo- EM grid. We are planning to screen different compound and grids made up of different metals, to see the effect on particle distribution and ice thickness.