Mayahuelin, a Type I Ribosome Inactivating Protein: Characterization, Evolution, and Utilization in Phylogenetic...

Area of Science:

• Plant Molecular Biology
• Agave Biochemistry
• Phylogenetics

Background:

• Agaves exhibit remarkable tolerance to extreme heat and drought conditions.
• The central spike of A. tequilana var. azul, crucial for plant survival, displays exceptional heat tolerance.
• A highly abundant 27 kDa protein, named mayahuelin, was identified in this heat-tolerant organ.

Purpose of the Study:

• To identify and characterize the abundant heat-tolerant protein in the A. tequilana var. azul spike.
• To investigate the distribution, conservation, and functional properties of mayahuelin across Agave species.
• To explore the utility of mayahuelin and its orthologs as markers for phylogenetic analysis within the Agave genus.

Main Methods:

• Protein identification using Liquid Chromatography-Mass Spectrometry/Mass Spectrometry (LC-MS/MS).
• Immunological detection using anti-mayahuelin antibodies in various Agave species.
• Analysis of mayahuelin's enzymatic activity using an in vitro wheat germ translation system.
• Gene sequencing and phylogenetic analysis of mayahuelin orthologs.

Main Results:

• Mayahuelin was identified as a type I Ribosome Inactivating Protein (RIP), primarily expressed in the spike, peduncle, and seeds of A. tequilana var. azul.
• The protein is conserved across multiple Agave species, with varying expression levels detected in spike leaves.
• Mayahuelin possesses unique active site substitutions (Y76D) and exhibits moderate inhibitory activity on protein synthesis.
• Allelic variations at the Y76 position of mayahuelin orthologs serve as effective phylogenetic markers, distinguishing wild accessions from cultivars.
• Phylogenetic analysis revealed close relatives of A. tequilana var. azul among specific accessions of A. rhodacantha and A. angustifolia.

Conclusions:

• Mayahuelin is a novel, heat-tolerant type I RIP with unique functional characteristics, playing a significant role in Agave's stress resistance.
• The conservation and allelic variations of mayahuelin provide valuable insights into Agave evolution and relationships.
• Mayahuelin sequences are robust markers for tracing the genetic origins and relationships of Agave varieties, including those used for tequila production.