The multiple cellular and physiological roles of the V-type proton pump in aquatic organisms

Abstract: V-type H+-ATPase (“proton pump” or VHA) is a multisubunit enzyme that uses the energy from ATP hydrolysis to transport protons across biological membranes. VHA is conserved in leukaryotes, playing a universal role in the endosomal-lysosomal pathway. In addition, VHA activity can drive the transport of diverse molecules across cell membranes and epithelia for specialized physiological functions. This presentation will discuss a few recently discovered VHA-dependent mechanisms in aquatic animals. For example, VHA in shark gills absorbs protons into the blood to counteract an alkalosis. In fish eyes, VHA acidifies red blood cells to promote oxygen unloading to the retina and sustain photoreception. In deep sea Osedax worms and in giant clams, VHA excretes acid onto bone and reef substrate to dissolve them thus providing nutrients and shelter. In midge larvae, VHA controls the contraction of air sacs that regulate buoyancy. And in several aquatic animals that establish symbiotic relationships with microbes, VHA acidifies the compartment that houses the symbionts, thus mediating metabolic coordination between symbiotic partners. These diverse physiological roles of VHA contribute to our understanding of fundamental cellular physiology of non-model species and provide insights about the evolution of complex physiological functions from conserved “building block” proteins. In addition, this knowledge can help identify physiological mechanisms that render a given species vulnerable or resilient to changing environments, and it may inspire biomedical biotechnological approaches. 

Bibliography: Martin Tresguerres is a Professor in Marine Biology at Scripps Institution of Oceanography (SIOUC San Diego). He completed his BS and MS in Aquatic Biology at the University of Buenos Aires (Argentina) (2001), his PhD in Physiology and Cell Biology at the University of Alberta (Canada) (2007), and his postdoc in molecular chemosensors at the Weill Cornell Medical College (New York City) (2010). Tresguerres’ research program at SIO-UCSD studies comparative and evolutionary physiology of aquatic organisms at the molecular, cellular, organismal, and environmental levels. His program deals with a diverse array of organisms including phytoplankton, invertebrates, and fish. Research at the Tresguerres Lab combines biomedicalgrade
and field research approaches to elucidate mechanisms underlying essential functions such as symbiosis, biomineralization, and neurobiology, their evolutionary bases, their relevance in the ‘real world’, and their responses to environmental variability.