Proteins Cause Ice Nucleation

Biological Strategy

Pseudomonas syringae

AskNature Team

Image: Jerzy Opioła / Wikimedia Commons / CC BY SA - Creative Commons Attribution + ShareAlike

Modify Phase

Gases, liquids, and solids are phases of matter found in and around living systems. Modifying these phases entails transforming from one to another, such as ice melting into liquid water or water turning into gas vapor. Phases of matter have different properties, so living systems need strategies to manage different phases. Modifying phases enables living systems to take advantage of the properties of more than one phase to carry out life activities. An example of how a living system manages and uses different phases is found in the rainforest. The forest obtains water from rain and some goes into the soil to be taken up by the roots. But some water remains in the forest’s canopy, where it evaporates to a gaseous phase and is carried elsewhere by air, descending again as rain on a different ecosystem.

Search this Function

Bacteria

Domain Bacteria (“small staff”): L. acidophilus, Staphylococcus

From inside of our own bodies to the deepest parts of the ocean, bacteria have adapted to almost every possible environment. All bacteria are unicellular, microscopic, and lack a membrane-bound nucleus and organelles, and come in three basic shapes: spherical (cocci), rod (bacilli), and spiral (spirilla). Some strains can be deadly, like Staphylococcus aureus (MRSA) while others, like Lactobacillus acidophilus, found in our intestinal microbiome, keep us healthy. Cyanobacteria, also known as blue green algae, caused the Great Oxidation Event 2.4 billion years ago, producing Earth’s first oxygenated atmosphere.

Search this Living System

The cells of Pseudomonas syringae, a plant pathogen, can cause ice nucleation via specific surface proteins.

“P. syringae is one of the few plant pathogens known to be disseminated up into clouds (Jayaweera and Flanagan, 1982; Sands et al., 1982). It is also scrubbed from the air during rain (Constantinidou et al., 1990). Many strains of this bacterium are ice nucleation-active (Lindow, 1983), are known to survive freezing as well as induce freezing, and it has been suggested that they might even have a role in inciting rainfall via their ice nucleation activity (Morris et al., 2004).” (Morris et al. 2007:85)

“Antifreeze s (AFPs) inhibit the growth of ice, whereas ice-nucleation proteins (INPs) promote its formation…Although several organisms have been identified as having ice-nucleation activity, the best characterized by biochemical methods are the bacterial INPs. Of these INPs, that of Pseudomonas syringae is often used as a representative protein.” (Graether and Jia 2001:1169)

Last Updated August 18, 2016

References

Journal article

Surprising niche for the plant pathogen Pseudomonas syringae

Morris, C. E.; Kinkel, L. L.; Xiao, K.; Prior, P.; Sands, D. C.

Journal article

Modeling Pseudomonas syringae ice-nucleation protein as a b-Helical protein

Graether, SP; Jia, Z

AskNature