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.
Mesh Terms:
Amino Acid Sequence, Cell Cycle Proteins, Crystallography, X-Ray, Dimerization, Genetic Complementation Test, Models, Molecular, Molecular Sequence Data, Mutagenesis, Site-Directed, Phosphoproteins, Protein Structure, Quaternary, Protein Structure, Secondary, Recombinant Proteins, Saccharomyces cerevisiae, Saccharomyces cerevisiae Proteins, Sequence Homology, Amino Acid
J. Mol. Biol.
Date: Sep. 22, 2006
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