Coral proteogenomics

Discovering metabolic pathways in coral plant-animal symbiosis

Prof. Aaron Timperman, Department of Chemistry and Biochemistry

Coral reefs are endangered world-wide from increased ocean surface water temperatures and increased ocean acidity. The frequency of coral bleaching events, which increase coral mortality, are increasing globally and this increase is well documented. Coral bleaching results when the coral (an animal) is stressed, and losses its symbiotic photosynthetic (algae), causing it to turn white and lose an important energy source.  In fact, coral is of a complex community, referred to as the holobiont that includes the coral (animal that builds the reef structure), symbiodinium (algae), bacteria, and fungi.  Great variability has been observed in the ability of different coral species to recover from bleaching events.  While it is well established that the algae store energy and pass it to the coral, little is known of how this process is actually achieved and how it varies among different coral species.  For example, the molecules used to pass energy are unknown and could be largely carbohydrates, lipids, amino acids, or other small molecules.  We believe that an improved understanding of the metabolic pathways of the coral holobiont is critical to assess the dependence of the different coral species on energy produced by their symbiotic algae.  This improved understanding of the metabolism of the coral holobiont is needed to assess the natural ability of coral to adapt to changing climate, and to determine what the best management practices should be for coral conservation. 

To better understand the metabolic processes used to store and metabolize energy, we are using proteogenomics to determine the relative abundance of metabolic enzymes present in the coral holobiont.  Through collaborations, the genomic sequences from each coral sample will be available and the potential enzymes that the different species present are capable of producing.  The REU student will be involved with developing methods to determine the best approach to extract protein from the coral samples, and perform relative quantitation using endogenous proteins as internal standards. Following the method development, the student will be involved with protein identification (targeting metabolic enzymes using high performance liquid chromatograph-mass spectrometry (HPLC-MS/MS), and analysis of the HPLC-MS/MS data. The relative abundance of the metabolic proteins are used to infer the metabolic pathways.  An extensive set of 480 samples of 8 Hawaiian coral species that will include exposures to high temperature, exposures to increased acidity, and controls will be available for this project.