The possibility of artificial life at subzero temperatures: the role of water in cell-mimicking compartments

Introduction

In the last few decades, researchers have come to believe that where there is liquid water, there is life, regardless of the physical conditions of the surroundings. Indeed, living organisms have been discovered in environments with extreme temperatures, radiation, or high salinity.

Temperature Limits

In terms of temperature, the lowest limit to sustain the metabolic activities of bacteria is reported to be -20 ºC in permafrost. Yet, the survival mechanism of life below the freezing point of water is still not fully understood, though it has important implications for origin of life studies and the search for life in the universe.

Importance of Liquid Water

The prerequisite of life at subzero temperatures is the existence of liquid water. Intracellular liquid water not only serves as a solution medium but also plays a crucial role in biological processes such as metabolism in cells. Therefore, understanding the physical state of intracellular water at subzero temperatures is important.

Project Overview

In ArtWater, we will employ synthetic compartments as a model system to investigate the physical state of compartmentalized water at subzero temperatures. The project will be conducted through a bottom-up approach:

1. From pure water in compartments to crowded compartmentalized solutions that mimic cytoplasm in natural cells.
2. The crystallization, diffusion, and dynamics of water will be studied by:
   • Differential scanning calorimetry
   • Nuclear magnetic resonance
   • Broadband dielectric spectroscopy

Synthetic Compartments

Several types of state-of-the-art synthetic compartments will be employed, including:

• Polymersomes
• Liposomes
• Complex coacervates

Development of Artificial Cells

Furthermore, we will develop artificial cells equipped with liquid water enabling biological activities at subzero temperatures.

Implications of the Project

The ArtWater project will not only open the window for understanding the survival mechanisms at extremely low temperatures but also provide a new platform for tunable bioengineering processes such as cryopreservation and cryo-enzymology, and shed light on astrobiology.