Enzymes for fast and efficient plastic degradation.
Due to their recalcitrant nature, the majority of the plastic waste remains untreated and consequently accumulates in Nature. A study indicates that by 2060, we will accumulate around 1000 million tons of plastic waste, endangering marine life and ecosystems.
The chemical and mechanical recycling of the waste is of little help, as it involves the release of large amounts of greenhouse gas.
Polyethylene terephthalate (PET), a semi-aromatic polyester, is one of the highly-consumed plastics with high resistance to biodegradation. However, recently discovered PET-degrading enzymes such as PETase or leaf-branch cutinase (LCC) offer promise to depolymerize PET in an environmental friendly manner. First, our laboratory will investigate the mechanistic aspects of such plastic-degrading enzymes using various bulk and single-molecule techniques. Later, insight gained from such studies will be employed to generate enzymes capable of degrading other kinds of plastic, such as nylons and polyethylene, via directed evolution approaches.
Dynamics of Odorant Receptors to Decode Smell
More than a hundred years ago, Alexander Graham Bell asked a classroom full of students, “Did you ever try to measure a smell? … Until you can measure their likenesses and differences, you can have no science of odor.” Indeed, even today, we remain unable to define physical parameters associated with smell—unlike vision (wavelength of light) or hearing (frequency of sound). Is it the size, charge or polarity the of odorant molecules that determines their characteristic smells? Or something else entirely?
In humans, the combinatorial activation of 391 odorant receptors (ORs) expressed on the membranes of olfactory sensory neurons enables our sense of smell. However, the precise mechanism by which ORs recognize odorant molecules remains unclear.
In this project, we aim to probe the dynamic changes in ORs upon odorant binding using single-molecule fluorescence techniques. The application of single-molecule methods will enhance the sensitivity of odorant-binding assays to the nanomolar–picomolar range—beyond the current state of the art. Moreover, these techniques will allow us to observe the ‘dance’ of ORs in the presence of odorant molecules, uncovering the molecular-level mechanisms underlying this most enigmatic of senses.
Far-red absorbing light-harvesting complexes.
With the world population approaching 8 billion soon, the disappearance of cultivable lands due to rapid urbanization, and the advent of anthropogenic climate change a food crisis is imminent. Several studies show that we need to double our food production by 2050 to avoid such a crisis. To meet this challenge, alternative avenues need to be discovered to increase agricultural output.
A promising avenue to enhance photosynthetic efficiency in plants is to extend the photosynthetically active radiation (PAR) to the infrared. Green plants use only the blue and red light for oxygenic photosynthesis, leaving the green and infrared parts mostly unused. It can be shown that a modest extension in the PAR to 750 nm could lead to a ~20% increase in photosynthetic efficiency. By employing a high-throughput microfluidic-assisted directed evolution platform, our laboratory aims to optimize the pigment-protein interactions beneficial for further far-red absorbing plant species.
Biosensors for single-molecule and super-resolution microscopies.
Fluorescent proteins (FPs)-based biomarkers have remained the state-of-the-art in biological assays as they can be expressed on proteins of interest at stoichiometric levels. Small organic fluorophores although bright and photostable often cannot be incorporated or attach to multiple species, preventing clear conclusions. In the last decade, directed evolution has achieved remarkable feat in enhancing the brightness of these FPs. However, the low photostability and high blinking make these probes unsuitable in single molecule applications where high illumination intensities are used. On the other hand, localization-based super-resolution techniques like PALM or STED rely on the on/off switching of the fluorophores.
Our laboratory aims to develop bright photoswitching FPs for advanced nanoscopy applications like MINFLUX by controlling their dark state conversion (DSC) and ground state recovery (GSR) processes which ultimately relates to their blinking properties and photostability.