Human myosin-5A and the intracellular transport of cargoes: studies of the myosin-5A and adapter proteins complexes

Abstract

Some proteins belonging to the myosin superfamily move along actin filaments using ATP hydrolysis to transport vesicles, organelles, mRNA, protein complexes and others cargoes. Myosin 5A (MYO5A) is an ubiquitous non-muscular myosin present in eukaryotic cells, which has been extensively investigated. MYO5A is a homodimeric molecular motor with semi-conserved primary sequence over the evolution and it contains the Globular Tail Domain (GTD) constituted basically by two alfa-helical subdomains at the C-terminal region (as demonstrated to its ortholog in S. cerevisiae), where the cargoes are linked before their transport. Typically the transport of cargoes does not occur by a direct interaction between cargoes and MYO5A; therefore, the presence of an Adapter Protein (AP) is often required to permit binding and subsequent transport. Thus, whether mutation or misregulation of either MYO5A or AP genes are developed in an organism, it can result into illness phenotypes such as the Griscelli Syndrome, a disease characterized by cutaneous and capillary albinism and severe neurological disorders. Motivated to shed light on the physio(patho)logical process in which human MYO5A can be involved, we have performed a screening in a fetal human brain library (where MYO5A is profusely expressed) using Yeast Two-Hybrid (YTH) System to identify new APs for the GTD (whose experiments were carried throughout undergraduate research). Then, this work aims to validate the putative molecular partners from the YTH screening and postulate its functional relevance and roles in the different regulatory pathways through biophysical and structural studies of MYO5A-AP complexes. These results will contribute to the better understanding of molecular mechanisms involved in cargoes transport, as well as in potentially associated diseases. (AU)