title: Myosin VI Contains a Compact Structural Motif that Binds to Ubiquitin Chains.
abstract: Myosin VI is critical for cargo trafficking and sorting during early endocytosis and autophagosome maturation, and abnormalities in these processes are linked to cancers, neurodegeneration, deafness, and hypertropic cardiomyopathy. We identify a structured domain in myosin VI, myosin VI ubiquitin-binding domain (MyUb), that binds to ubiquitin chains, especially those linked via K63, K11, and K29. Herein, we solve the solution structure of MyUb and MyUb:K63-linked diubiquitin. MyUb folds as a compact helix-turn-helix-like motif and nestles between the ubiquitins of K63-linked diubiquitin, interacting with distinct surfaces of each. A nine-amino-acid extension at the C-terminal helix (Helix2) of MyUb is required for myosin VI interaction with endocytic and autophagic adaptors. Structure-guided mutations revealed that a functional MyUb is necessary for optineurin interaction. In addition, we found that an isoform-specific helix restricts MyUb binding to ubiquitin chains. This work provides fundamental insights into myosin VI interaction with ubiquitinated cargo and functional adaptors.
authors.affiliation: Protein Processing Section, Structural Biophysics Laboratory, Center for Cancer Research, National Cancer Institute, Frederick, MD 21702, USA.
authors.forename: Fahu
authors.initials: F
authors.lastname: He
authors.affiliation: IFOM, Fondazione Istituto FIRC di Oncologia Molecolare, Via Adamello 16, 20139 Milano, Italy.
authors.forename: Hans-Peter
authors.initials: HP
authors.lastname: Wollscheid
authors.affiliation: Protein Processing Section, Structural Biophysics Laboratory, Center for Cancer Research, National Cancer Institute, Frederick, MD 21702, USA.
authors.forename: Urszula
authors.initials: U
authors.lastname: Nowicka
authors.affiliation: IFOM, Fondazione Istituto FIRC di Oncologia Molecolare, Via Adamello 16, 20139 Milano, Italy.
authors.forename: Matteo
authors.initials: M
authors.lastname: Biancospino
authors.affiliation: IFOM, Fondazione Istituto FIRC di Oncologia Molecolare, Via Adamello 16, 20139 Milano, Italy.
authors.forename: Eleonora
authors.initials: E
authors.lastname: Valentini
authors.affiliation: Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, MN 55455, USA.
authors.forename: Aaron
authors.initials: A
authors.lastname: Ehlinger
authors.affiliation: IFOM, Fondazione Istituto FIRC di Oncologia Molecolare, Via Adamello 16, 20139 Milano, Italy.
authors.forename: Filippo
authors.initials: F
authors.lastname: Acconcia
authors.affiliation: IFOM, Fondazione Istituto FIRC di Oncologia Molecolare, Via Adamello 16, 20139 Milano, Italy.
authors.forename: Elisa
authors.initials: E
authors.lastname: Magistrati
authors.affiliation: IFOM, Fondazione Istituto FIRC di Oncologia Molecolare, Via Adamello 16, 20139 Milano, Italy; DIPO, Dipartimento di Oncologia ed Emato-oncologia, Università degli Studi di Milano, Via di Rudinì 8, 20122 Milan, Italy. Electronic address: simona.polo@ifom.eu.
authors.forename: Simona
authors.initials: S
authors.lastname: Polo
authors.affiliation: Protein Processing Section, Structural Biophysics Laboratory, Center for Cancer Research, National Cancer Institute, Frederick, MD 21702, USA. Electronic address: kylie.walters@nih.gov.
authors.forename: Kylie J
authors.initials: KJ
authors.lastname: Walters
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D005454:Fluorescence Polarization; D057809:HEK293 Cells; D006801:Humans; D009682:Magnetic Resonance Spectroscopy; D008969:Molecular Sequence Data; D018995:Myosin Heavy Chains / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D017434:Protein Structure, Tertiary; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000737:chemistry / Q000302:isolation & purification; D016415:Sequence Alignment; D025801:Ubiquitin / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*
chemical_list: D011994:Recombinant Proteins; D025801:Ubiquitin; C089785:myosin VI; D018995:Myosin Heavy Chains