| Budget Amount *help |
¥3,600,000 (Direct Cost: ¥3,600,000)
Fiscal Year 2005: ¥1,500,000 (Direct Cost: ¥1,500,000)
Fiscal Year 2004: ¥2,100,000 (Direct Cost: ¥2,100,000)
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| Research Abstract |
AAA-ATPases are well conserved molecular machines from bacteria to human, which alters the conformations and/or multimerization states of substrate proteins with an ATP-depending manner. AAA-ATPases are characterized as harboring one or several "AAA" domains at their central region of the molecules, whereas various N-terminus domains may be responsible for differentiating their specific functions. I have hypothesized that some of them can be responsible not only for their substrate specificity, but also for their subcellular location. In order to solve this problem, so-called "protein domain anatomy" approach was taken.
As a result, first we have identified a novel domain from the PEX1 N-terminal region. Surprisingly, although below 15% of sequence identity found to VCP and NSF, the structure of PEX1NTD is very similar to those corresponding domains. Second, we have identified the solution structures from N-terminal MIT domain of Vps4 type I AAA-ATPase and its distant homolog katanin p60. These domains adopted into an up-and-down three helix bundle fold with a characteristic cleft on the molecular surface, which may act as a ligand binding site, katanin p60 N-terminal domain was associated with a coiled-coil region, which should be designed prior to structural analysis. Some other AAA-ATPases require a shuttle factor molecule instead of its own adaptor domain. From one of them, we determined the solution structure of UBA domain from Dsk2 protein, an adaptor of 19S proteosome, in complex with ubiquitin. In addition, molecular rigidity and flexibility of K48- and K63-linked tetra ubiquitin chain were compared by using solution NMR.
Finally, two domains of the five examined systems were found to have affinities to phosphoinositides. This suggested the domains share a function for associating organellar membranes.
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