Structural and functional analysis of Saccharomyces cerevisiae Mob1.
The Mob proteins function as activator subunits for the Dbf2/Dbf20 family of protein kinases. Human and Xenopus Mob1 protein structures corresponding to the most conserved C-terminal core, but lacking the variable N-terminal region, have been reported and provide a framework for understanding the mechanism of Dbf2/Dbf20 regulation. Here, we report the 2.0 A X-ray crystal structure of Saccharomyces cerevisiae Mob1 containing both the conserved C-terminal core and the variable N-terminal region. Within the N-terminal region, three novel structural elements are observed; namely, an alpha-helix denoted H0, a strand-like element denoted S0 and a short beta strand denoted S-1. Helix H0 associates in an intermolecular manner with a second Mob1 molecule to form a Mob1 homodimer. Strand S0 binds to the core domain in an intramolecular manner across a putative Dbf2 binding site mapped by Mob1 temperature-sensitive alleles and NMR binding experiments. In vivo functional analysis demonstrates that Mob1 mutants that target helix H0 or its reciprocal binding site are biologically compromised. The N-terminal region of Mob1 thus contains structural elements that are functionally important.
Mrkobrada
Serge
S
Program in Molecular Biology and Cancer, Samuel Lunenfeld Research Institute, Mount Sinai Hospital, Toronto, Ontario Canada M5G 1X5.
Boucher
Lorrie
L
Ceccarelli
Derek F J
DF
Tyers
Mike
M
Sicheri
Frank
F
D000595:Amino Acid Sequence; D018797:Cell Cycle Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D018360:Crystallography, X-Ray; D019281:Dimerization; D005816:Genetic Complementation Test; D008958:Models, Molecular; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D010750:Phosphoproteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D020836:Protein Structure, Quaternary; D017433:Protein Structure, Secondary; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D017386:Sequence Homology, Amino Acid
D018797:Cell Cycle Proteins; C110689:MOB1 protein, S cerevisiae; D010750:Phosphoproteins; D011994:Recombinant Proteins; D029701:Saccharomyces cerevisiae Proteins