The long-term goal of this research project is to understand the enzymatic properties, motor properties, and cellular functions of myosin XIX (Myo19), a molecular motor protein involved in the transport and localization of mitochondria, an organelle central to multiple cellular processes. Mitochondrial dynamics have been shown to be partially actin-based, and mutations in other genes involved in mitochondrial dynamics lead to human diseases. Additionally, microarray analyses indicate that Myo19 expression is increased in certain cancers, compared to normal tissues. Previous studies show that Myo19 plays a role in mitochondrial motility in cultured cells as expression of GFP-tagged Myo19 constructs alters mitochondrial dynamics in a pulmonary cancer cell line and in a cultured neuronal cell line. Taken together, analysis of the Myo19 protein sequence and analysis of the effect of GFP-Myo19 expression in cultured cells lead to the hypothesis that Myo19 plays a role in mitochondrial dynamics, as it contains a conserved myosin motor domain and interacts with mitochondria via its tail domain. We will use both Myo19 knock-down and overexpression of functional and non-functional Myo19 constructs in cell culture models of cell division and apoptosis to determine what role Myo19 may play in each of those processes. Expression and purification of Myo19 motor domain will allow for a complete in vitro analysis of the rate and equilibrium constants associated with the motor properties of Myo19. Additionally, purified protein will be used to directly examine the motor properties of Myo19 using an in vitro actin sliding filament motility assay system. Examination of both the enzymatic and motor characteristics of Myo19 in vitro will allow the determination of the mechanism by which Myo19 motor activity generates force, and determination of factors that may regulate its function in vivo. By examining the functional roles, enzymatic properties, and motor properties, of Myo19, these proposed studies will further our understanding of mitochondrial dynamics in health and disease.
Mitochondria play critical roles in healthy cellular function, most importantly the production of energy inside the cell. These powerhouses must be able to move to locations within the cell where energy needs are high, and alterations in these transport mechanisms have been associated with human disease. Myosin XIX is a motor protein involved in mitochondrial transport, and studying its motor properties will aid in the understanding of mitochondrial transport in both healthy and disease conditions.
|Singh, Pali P; Hawthorne, Jenci L; Davis, Christie A et al. (2016) Permeabilization activated reduction in fluorescence: A novel method to measure kinetics of protein interactions with intracellular structures. Cytoskeleton (Hoboken) 73:271-85|
|Schenkelaars, Quentin; Quintero, Omar; Hall, Chelsea et al. (2016) ROCK inhibition abolishes the establishment of the aquiferous system in Ephydatia muelleri (Porifera, Demospongiae). Dev Biol 412:298-310|
|Hawthorne, Jenci L; Mehta, Prachi R; Singh, Pali P et al. (2016) Positively charged residues within the MYO19 MyMOMA domain are essential for proper localization of MYO19 to the mitochondrial outer membrane. Cytoskeleton (Hoboken) 73:286-99|
|Mecklenburg, Kirk L; Freed, Stephanie A; Raval, Manmeet et al. (2015) Invertebrate and vertebrate class III myosins interact with MORN repeat-containing adaptor proteins. PLoS One 10:e0122502|
|Rohn, Jennifer L; Patel, Jigna V; Neumann, Beate et al. (2014) Myo19 ensures symmetric partitioning of mitochondria and coupling of mitochondrial segregation to cell division. Curr Biol 24:2598-605|
|Adikes, Rebecca C; Unrath, William C; Yengo, Christopher M et al. (2013) Biochemical and bioinformatic analysis of the myosin-XIX motor domain. Cytoskeleton (Hoboken) 70:281-95|
|Quintero, Omar A; Unrath, William C; Stevens Jr, Stanley M et al. (2013) Myosin 3A kinase activity is regulated by phosphorylation of the kinase domain activation loop. J Biol Chem 288:37126-37|
|Merritt, Raymond C; Manor, Uri; Salles, Felipe T et al. (2012) Myosin IIIB uses an actin-binding motif in its espin-1 cargo to reach the tips of actin protrusions. Curr Biol 22:320-5|
|Quintero, Omar A; Yengo, Christopher M (2012) Myosin X dimerization and its impact on cellular functions. Proc Natl Acad Sci U S A 109:17313-4|
|Phelps, David S; Umstead, Todd M; Quintero, Omar A et al. (2011) In vivo rescue of alveolar macrophages from SP-A knockout mice with exogenous SP-A nearly restores a wild type intracellular proteome; actin involvement. Proteome Sci 9:67|