Research Focus

Dr. Mitra's post-doctoral research at UC Berkeley was focused on the identification of novel genes and proteins that are involved involved in acclimation mechanisms to fluctuations in irradiance in the unicellular green alga Chlamydomonas reinhardtii. Her postdoctoral research project specifically involved identifying and characterizing novel genes that define the chlorophyll antenna size in the model green alga C. reinhardtii employing biochemical and molecular approaches. 

tla1, (truncated light harvesting chlorophyll antenna size) a chlorophyll deficient mutant with a smaller Chl antenna size compared to that of the wild type was identified upon screening of an nuclear DNA insertional mutant library. The TLA1 gene encodes a novel protein of 213 amino acids and shows substantial homology to proteins of unknown function in diverse eukaryotic organisms, ranging from higher plants to invertebrates and mammals. Through application of computational-based bioinformatics tools Dr. Mitra has shown that the conserved domains of TLA1 like proteins have a remote homology with the plain MPN/MOV34 domains, which are domains present in proteins involved in protein degradation, translation factors and transcription regulators like subunits of COP9 signalosome (CSN6), eukaryotic translation initiation factor (eIF3f and eIF3h) etc.

Dr. Mitra performed over-expression and down-regulation of the TLA1 gene (using RNA interference) to alter the optical properties of green algae by conferring a larger or truncated, Chl antenna size. The over-expression and down regulation of the TLA1 gene affected the concentration of some of the major photosynthetic proteins and altered the organization of the thylakoid membrane structure in the chloroplast. Her post-doctoral research has important application in algal biotechnology for improving photosynthetic productivity and solar conversion efficiency of commercially important photosynthetic microalgae, biomass accumulation and carbon sequestration (see her research patent from UC Berkeley). 

tla1, is a chlorophyll deficient mutant with a small chlorophyll antenna size, reflective in the high chl a/b ratio as shown above (middle two figures). tla1 was generated by nuclear DNA insertional mutagenesis of the strain CC425 (deficient in argininosuccinate lyase, an enzyme required for arginine biosynthesis) using the pJD67 plasmid, containing the argininosuccinate lyase (ARG7) gene. tla1-comp1, 2 & 3 are three tla1 complements displaying wild type chlorophyll pigmentation.