Structure and ESCRT-III protein interactions of the MIT domain of human VPS4A.
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.
Scott
Anna
A
Department of Biochemistry, 20 N, 1900 E, University of Utah School of Medicine, Salt Lake City, UT 84132-3201, USA.
Gaspar
Jason
J
Stuchell-Brereton
Melissa D
MD
Alam
Steven L
SL
Skalicky
Jack J
JJ
Sundquist
Wesley I
WI
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
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