Structural mechanism for versatile cargo recognition by the yeast class V myosin Myo2

Abstract

Edited by Wolfgang PetiClass V myosins are actin-dependent motors, which recognize numerous cellular cargos mainly via the C-terminal globular tail domain (GTD). Myo2, a yeast class V myosin, can transport a broad range of organelles. However, little is known about the capacity of Myo2-GTD to recognize such a diverse array of cargos specifically at the molecular level. Here, we solved crystal structures of Myo2-GTD (at 1.9 -3.1 Å resolutions) in complex with three cargo adaptor proteins: Smy1 (for polarization of secretory vesicles), Inp2 (for peroxisome transport), and Mmr1 (for mitochondria transport). The structures of Smy1-and Inp2bound Myo2-GTD, along with site-directed mutagenesis experiments, revealed a binding site in subdomain-I having a hydrophobic groove with high flexibility enabling Myo2-GTD to accommodate different protein sequences. The Myo2-GTD-Mmr1 complex structure confirmed and complemented a previously identified mitochondrion/vacuole-specific binding region. Moreover, differences between the conformations and locations of cargo-binding sites identified here for Myo2 and those reported for mammalian MyoVA (MyoVA) suggest that class V myosins potentially have co-evolved with their specific cargos. Our structural and biochemical analysis not only uncovers a molecular mechanism that explains the diverse cargo recognition by Myo2-GTD, but also provides structural information useful for future functional studies of class V myosins in cargo transport.Class V myosins have long been recognized as key molecular motors involved in intracellular transport along actin filaments. Mammals contain three class V myosins, MyoVa/b/c, whereas the budding yeast Saccharomyces cerevisiae has two, Myo2 and

Type V myosin focuses the polarisome and shapes the tip of yeast cells

“…Site I binds to the Rab GTPases Sec4, Ypt32, Ypt31, and Ypt32; the microtubule adaptor Kar9; and the peroxisomal receptor Inp2. Site II binds to the mitochondrial and vacuolar receptors Mmr1 and Vac17, and site III binds exclusively to the exocyst subunit Sec15 ( Jin et al, 2011 ; Fagarasanu et al, 2009 ; Eves et al, 2012 ; Lipatova et al, 2008 ; Tang et al, 2019 ). By changing central residues that specifically affect the interaction with known ligands for each site, we were able to identify binding site I of Myo2 as a potential interface for Pea2 ( Fig.…”

Structure of the class XI myosin globular tail reveals evolutionary hallmarks for cargo recognition in plants

“…The mitochondria/vacuole-binding site of Myo2p has also diverged in mammalian MyoVs (Nascimento et al, 2013), giving rise to a melanophilin (Mlph)-binding site in MyoVa that partially overlaps with this region (Tang et al, 2019;Wei et al, 2013). An extension of the 6 helix along with changes in the orientation of 4 and 6 in Myo2p and MyoXI-K impairs any similar interaction with Mlph, which correlates with the lack of homologs of this mammalian protein in yeast (Mast et al, 2012) and plants (Figs.…”

“…On face C, at the opposite side to the Mmr1-binding site in lobule I, the peroxisome receptor Inp2 binds to a groove lined mostly by neutral residues in Myo2p GTD (Tang et al, 2019;Fig. 5a).…”

Regulation of the early stages of endoplasmic reticulum inheritance during ER stress

“…The inheritance of most organelles relies on the directional transport of motor proteins on cytoskeletal tracks provided by either actin or microtubules. For instance, vacuoles and peroxisomes are transferred into the daughter cell by Myosin 2 on actin cables (Provance and Mercer, 1999;Fagarasanu et al, 2006;Peng and Weisman, 2008;Tang et al, 2019), while nuclear inheritance is dependent on microtubules (Du et al, 2004). The endoplasmic reticulum (ER) is morphologically distinct from other organelles; it consists of a continuous network of membrane tubules and sheets that undergo reorganization.…”