Structural characterization of the MIT domain from human Vps4b.
The microtubule interacting and trafficking (MIT) domain is a small protein module of unknown function that is conserved in proteins of diverse function, such as Vps4, sorting nexin 15 (SNX15), and spastin. One non-synonymous single nucleotide polymorphism was reported, which results in a Ile58-to-Met (I58M) substitution in hVps4b. Here, we have determined the solution structure of the MIT domain isolated from the NH(2)-terminus of human Vps4b, an AAA-ATPase involved in multivesicular body formation. The MIT domain adopts an 'up-and-down' three-helix bundle. Comparison with the sequences of other MIT domains clearly shows that the residues involved in inter-helical contacts are well conserved. The Ile58-to-Met substitution resulted a substantial thermal instability. In addition, we found a shallow crevice between helices A and C that may serve as a protein-binding site. We propose that the MIT domain serves as a putative adaptor domain for the ESCRT-III complex involved in endosomal trafficking.
Takasu
Hirotoshi
H
International Graduate School of Arts and Sciences, Yokohama City University, Yokohama, Kanagawa 230 0045, Japan.
Jee
Jun Goo
JG
Ohno
Ayako
A
Goda
Natsuko
N
Fujiwara
Kenichiro
K
Tochio
Hidehito
H
Shirakawa
Masahiro
M
Hiroaki
Hidekazu
H
D000074183:ATPases Associated with Diverse Cellular Activities; D000251:Adenosine Triphosphatases / Q000032:analysis / Q000737:chemistry*; D000595:Amino Acid Sequence; D003198:Computer Simulation; D056827:Endosomal Sorting Complexes Required for Transport; D006801:Humans; D008956:Models, Chemical; D008958:Models, Molecular; D008969:Molecular Sequence Data; D011487:Protein Conformation; D017434:Protein Structure, Tertiary; D012097:Repressor Proteins / Q000032:analysis / Q000737:chemistry*; D020539:Sequence Analysis, Protein; D033921:Vesicular Transport Proteins
D056827:Endosomal Sorting Complexes Required for Transport; D012097:Repressor Proteins; D033921:Vesicular Transport Proteins; D000251:Adenosine Triphosphatases; D000074183:ATPases Associated with Diverse Cellular Activities; C490304:VPS4B protein, human