Distinguished Professor University of Massachusetts Amherst Amherst, Massachusetts
Body of Abstract: ATAD3 proteins (ATPase family AAA domain-containing protein 3) are unique mitochondrial proteins comprising a C-terminal AAA+ domain in the mitochondrial matrix and an ATAD3_N domain of unknown function that spans the mitochondrial membranes, potentially reaching the cytosol to interact with the ER. ATAD3s are absent from yeasts, but are essential in humans, Drosophila and Dictyostelium, and we show they are essential in the moss Physcomitrium patens and the seed plant Arabidopsis thaliana. P. patens has two ATAD3 genes, PpA and PpB. Null ppb mutants grow well and have minor mitochondrial defects. In contrast, null ppa single mutants are severely stunted and have aberrant, variably-sized mitochondria that lack inner membranes and are significantly less motile than wild type mitochondria. Increased PpB expression in ppa mutants enhances growth, suggesting PpA is essential. A. thaliana has four ATAD3 genes in two clades: AtA1 and A2, and AtB1 and B2. Diversification of ATAD3 into two clades occurred in the seed plant lineage. Bimolecular fluorescence complementation indicates these proteins can all heterodimerize. Single A. thaliana ATAD3 mutants are wildtype, but mutation of both genes from either clade is lethal. A. thaliana plants with disrupted ATAD3 function show enlarged mitochondria, reduced Complex I and disrupted nucleoids. In total, our data demonstrate ATAD3s contribute to essential mitochondrial functions across evolutionarily divergent organisms. Investigations of ATAD3s are being incorporated into a Biotech at San Diego State University Scholars Program (BT@SDSU) that provides mentoring and professional development for students from backgrounds underrepresented in STEM. Three cohorts of 14 BT@SDSU Scholars will gain research experience, assistance to obtain biotech internships, skills for the job market, practice in science communication, and a community of peers and science professionals. These opportunities are known to increase motivation and persistence toward STEM careers, and the specific impact of BT@SDSU on Scholars will be investigated.