title: Structure and ESCRT-III protein interactions of the MIT domain of human VPS4A.
abstract: The VPS4 AAA ATPases function both in endosomal vesicle formation and in the budding of many enveloped RNA viruses, including HIV-1. VPS4 proteins act by binding and catalyzing release of the membrane-associated ESCRT-III protein lattice, thereby allowing multiple rounds of protein sorting and vesicle formation. Here, we report the solution structure of the N-terminal VPS4A microtubule interacting and transport (MIT) domain and demonstrate that the VPS4A MIT domain binds the C-terminal half of the ESCRT-III protein, CHMP1B (Kd = 20 +/- 13 microM). The MIT domain forms an asymmetric three-helix bundle that resembles the first three helices in a tetratricopeptide repeat (TPR) motif. Unusual interhelical interactions are mediated by a series of conserved aromatic residues that form coiled-coil interactions between the second two helices and also pack against the conserved alanines that interdigitate between the first two helices. Mutational analyses revealed that a conserved leucine residue (Leu-64) on the third helix that would normally bind the fourth helix in an extended TPR is used to bind CHMP1B, raising the possibility that ESCRT-III proteins may bind by completing the TPR motif.
authors.affiliation: Department of Biochemistry, 20 N, 1900 E, University of Utah School of Medicine, Salt Lake City, UT 84132-3201, USA.
authors.forename: Anna
authors.initials: A
authors.lastname: Scott
authors.forename: Jason
authors.initials: J
authors.lastname: Gaspar
authors.forename: Melissa D
authors.initials: MD
authors.lastname: Stuchell-Brereton
authors.forename: Steven L
authors.initials: SL
authors.lastname: Alam
authors.forename: Jack J
authors.initials: JJ
authors.lastname: Skalicky
authors.forename: Wesley I
authors.initials: WI
authors.lastname: Sundquist
mesh_terms: D000074183:ATPases Associated with Diverse Cellular Activities; D000251:Adenosine Triphosphatases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D000595:Amino Acid Sequence; D017124:Conserved Sequence; D004252:DNA Mutational Analysis; D056827:Endosomal Sorting Complexes Required for Transport; D006801:Humans; D007930:Leucine / Q000235:genetics; D008565:Membrane Proteins / Q000737:chemistry* / Q000378:metabolism; D008870:Microtubules / Q000378:metabolism; D008969:Molecular Sequence Data; D009154:Mutation; D009687:Nuclear Proteins / Q000737:chemistry* / Q000378:metabolism; D025941:Protein Interaction Mapping; D017433:Protein Structure, Secondary; D012097:Repressor Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D025262:Vacuolar Proton-Translocating ATPases; D033921:Vesicular Transport Proteins
chemical_list: C443709:CHMP1A protein, human; C541483:CHMP1B protein, human; D056827:Endosomal Sorting Complexes Required for Transport; D008565:Membrane Proteins; D009687:Nuclear Proteins; D012097:Repressor Proteins; D033921:Vesicular Transport Proteins; D000251:Adenosine Triphosphatases; D025262:Vacuolar Proton-Translocating ATPases; D000074183:ATPases Associated with Diverse Cellular Activities; C490305:VPS4A protein, human; D007930:Leucine