title: Oligomeric Aip2p/Dld2p forms a novel grapple-like structure and has an ATP-dependent F-actin conformation modifying activity in vitro.
abstract: In order to investigate the molecular mechanism of the F-actin conformation modifying activity [Biochem. Biophys. Res. Commun. 319 (2004) 78] of actin-interacting protein 2 (Aip2p) [Nat. Struct. Biol. 2 (1995) 28]/D-lactate dehydrogenase protein 2 (Dld2p) [Yeast 15 (1999) 1377; Biochem. Biophys. Res. Commun. 295 (2002) 910], the ultrastructure and the regulatory mechanism of the activity were further examined. Interestingly, a novel oligomeric grapple-like structure of 10-12 subunits with an ATP-dependent opening was observed. ATP regulates the opening and closing of the "gate" that forms the opening within oligomeric Aip2p/Dld2p, where binding to the substrate occurs while in the open form. In the presence of ATP (open state of oligomeric Aip2p/Dld2p), oligomeric Aip2p/Dld2p bound the F-actin fiber within the opening, whereas in the absence of ATP (closed state of oligomeric Aip2p/Dld2p), no binding was observed. Simultaneously, the oligomeric Aip2p/Dld2p increased the trypsin susceptibility of F-actin in an ATP-dependent manner. Use of the non-hydrolyzable ATP analogue AMP-PNP yielded similar results to those observed with ATP, suggesting that ATP binding rather than ATP hydrolysis is required for the protein conformation modifying reaction of oligomeric Aip2p/Dld2p. Endogenous Aip2p/Dld2p purified from Saccharomyces cerevisiae also exhibited such protein conformation modifying activity, but monomeric Aip2p/Dld2p with a C-terminal coiled-coil region-truncation failed to exhibit the activity. These data suggest that the oligomerization of Aip2p/Dld2p, which exhibits the unique grapple-like structure with an ATP-dependent opening, is required for the F-actin conformation modifying activity.
authors.affiliation: Department of Cortical Function Disorders, National Institute of Neuroscience, National Center of Neurology and Psychiatry, Tokyo, Japan.
authors.forename: Naomi S
authors.initials: NS
authors.lastname: Hachiya
authors.forename: Yuji
authors.initials: Y
authors.lastname: Sakasegawa
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Sasaki
authors.forename: Akiko
authors.initials: A
authors.lastname: Jozuka
authors.forename: Shoichiro
authors.initials: S
authors.lastname: Tsukita
authors.forename: Kiyotoshi
authors.initials: K
authors.lastname: Kaneko
mesh_terms: D000199:Actins / Q000737:chemistry*; D000255:Adenosine Triphosphate / Q000737:chemistry*; D019281:Dimerization; D007770:L-Lactate Dehydrogenase / Q000737:chemistry* / Q000648:ultrastructure*; D042844:L-Lactate Dehydrogenase (Cytochrome); D011108:Polymers / Q000737:chemistry; D011485:Protein Binding; D011487:Protein Conformation; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry* / Q000648:ultrastructure*
chemical_list: D000199:Actins; D011108:Polymers; D029701:Saccharomyces cerevisiae Proteins; D000255:Adenosine Triphosphate; D007770:L-Lactate Dehydrogenase; D042844:L-Lactate Dehydrogenase (Cytochrome); C487563:DLD2 protein, S cerevisiae