Protein Homeostasis Lab | Department of Life Sciences

Protein Homeostasis Lab

laboratory is interested in understanding the regulation of intracellular protein homeostasis and its alterations during stress and aging.

Project 1: Elucidating the novel regulators of mitochondrial protein quality control

Mitochondrial dysfunction and loss of proteostasis have been designated as two major hallmarks of aging. Mitochondria, an organelle of endosymbiotic origin, has become critically dependent for its protein pool on the host cell nuclear genome despite harbouring its own DNA and complete protein synthesis apparatus. Moreover, the complex two-membrane boundary of the organelle make the whole process of protein import, sorting into intra-mitochondrial compartments and finally folding into functional native form, a mammoth task. Designated molecular chaperones belonging to various classes maintain the mitochondrial protein homeostasis (can be called as 'mitostasis') although the stress sensors and effectors to restore the homeostasis, still remain elusive. Using yeast, S.cerevisiae,  as a model system we are trying to elucidate the mitochondrial stress response pathways using forward and reverse genetics in yeast. We also extensively use various biochemical and biophysical assays to address the problem. Various next-gen technologies like RNA sequencing, quantitative proteomics are also employed to address the question, in collaboration with various institutes like CSIR-IGIB, CSIR-CCMB etc.  

Project 2: Delineation of molecular basis of Hsp70/Hsp110 chaperone function and the role of domain allostery in functionality of these molecular machines (supported by SERB)

Hsp70s  are ubiquitous molecular chaperones involved in plethora of cellular functions. The physiological roles of this group of chaperones are tightly regulated by its helper proteins, also known as co-chaperones and mainly achieved by allosteric communication between its two functional modules/domains. An important sub-class of Hsp70s, called Hsp110s (Hsp105 in mammals) has been shown to function as nucleotide exchange factors (NEFs) for Hsp70s. The most striking feature of Hsp110s are its structural similarity with Hs70s. Hsp110s are also modular proteins like Hsp70s and contain two functional domains,  N-terminal nucleotide binding domains and C-terminal peptide binding domain connected by a short linker sequence. So far, no NEF of Hsp70s were found to contain such two domain structures. Apart from its co-chaperone functions, Hsp110s have been implicated as a key aggregation preventing factor in many neurodegenerative disorders and it has been shown to harbour individual chaperone function. We are interested to elucidate the rationale of the Hsp70-like two-domain structure of Hsp110s and presence of domain allostery in Hsp110 proteins. To address the question, we employ protein biochemistry and sophisticated spectroscopy techniques like single molecule FRET, ensemble FRET and other structural studies like SAXS in collaboration with various groups in CSIR-IMTECH, CSIR-IGIB, IISER-Pune etc.


Project 3: Deciphering the unique chaperone function of Human Hsp60 in maintaining mitochondrial proteostasis

Hsp60 chaperone, a member of the Class I chaperonin family, is a key player in maintenance of protein homeostasis of mitochondrial matrix, the innermost and major hub of mitochondrial biochemical reactions. The importance of Hsp60  in intracellular processes is underscored by its essentiality for cell viability and by association of a number of genomic variations in the Hsp60 gene in various devastating diseases. Various single substitution mutations of the protein have been found to be the causative factor for severely debilitating neurological disorders like  Hereditary Spastic Paraplegia and Hypomyelinating leukodystrophy (HMLs), although the molecular level understanding of pathogenesis of such diseases remain largely obscure. Mechanistic details of chaperonine pathway of bacterial Hsp60/10 is very well established, although the working hypothesis of the human counterpart remains elusive. We are trying to understand whether the human Hsp60/10 system works in a similar manner to the bacterial protein and whether the common variants of human hsp60 gene affect the functionality of the protein. To address the question, we extensively employ molecular biology and protein biochemistry methods.



Lab R201 and office R214

Dr. Koyeli Mapa

Lab Equipments