Structural Characterization of Chitinases from Agave tequilana

07/10/2019

The economically important plant genus Agave is cultivated to produce fiber, food, beverages, and fuel. Within this genus, A. tequilana is primarily used for the elaboration of beverages and in soil conservation, but research indicates it’s potential as a source of lignocellulosic bioenergy feedstocks. It therefore has great socioeconomic and agroecological value, especially in hot and drought-prone regions of the world. Despite its adaptability, these plants are subject to diseases such as those caused by insects and fungus.

Plant chitinases are enzymes that hydrolyze chitin, a molecule present in fungal cell walls, most insect exoskeletons, yeasts and algae, crustacean shells, and other organisms. They are also involved in numerous plant physiological events such as abiotic stress responses, including antifungal activity and defense mechanisms.

In this study, the authors describe the solution structure and biophysical characterization of two chitinases from A. tequilana as determined by small-angle X-ray scattering (SAXS) at the Stanford Synchrotron Radiation Lightsource in combination with theoretical structure prediction using Robetta, a protein structure prediction service.

The low-resolution structures both exhibited two distinct domains connected by a linker region, and the theoretically predicted Rosetta structure showed consistency with the solution structures and could be docked into the SAXS envelopes. Interestingly, AtChi1 and AtChi2 both showed antifungal activities, suggesting that the Agave enzymes are involved in host defense mechanisms. Therefore, these enzymes could be considered as pathogenesis-related proteins with an important role in the plant’s defense mechanism against fungi.

References

Sierra-Gomez, Y., et al. 2019. “A Biophysical and Structural Study of Two Chitinases from Agave tequilana and Their Potential Role as Defense Proteins,” The FEBS Journal 286(23), 4778−96. [DOI:DOI:10.1111/febs.14993]