PMID:15525650
| Citation |
Vitavska, O, Merzendorfer, H and Wieczorek, H (2005) The V-ATPase subunit C binds to polymeric F-actin as well as to monomeric G-actin and induces cross-linking of actin filaments. J. Biol. Chem. 280:1070-6 |
|---|---|
| Abstract |
Previously, we have shown that the V-ATPase holoenzyme as well as the V1 complex isolated from the midgut of the tobacco hornworm (Manduca sexta) exhibits the ability of binding to actin filaments via the V1 subunits B and C (Vitavska, O., Wieczorek, H., and Merzendorfer,H. (2003) J. Biol. Chem. 278, 18499-18505). Since the recombinant subunit C not only enhances actin binding of the V1 complex but also can bind separately to F-actin, we analyzed the interaction of recombinant subunit C with actin. We demonstrate that it binds not only to F-actin but also to monomeric G-actin. With dissociation constants of approximately 50 nm, the interaction exhibits a high affinity, and no difference could be observed between binding to ATP-G-actin or ADP-G-actin, respectively. Unlike other proteins such as members of the ADF/cofilin family, which also bind to G- as well as to F-actin, subunit C does not destabilize actin filaments. On the contrary, under conditions where the disassembly of F-actin into G-actin usually occurred, subunit C stabilized F-actin. In addition, it increased the initial rate of actin polymerization in a concentration-dependent manner and was shown to cross-link actin filaments to bundles of varying thickness. Apparently bundling is enabled by the existence of at least two actin-binding sites present in the N- and in the C-terminal halves of subunits C, respectively. Since subunit C has the possibility to dimerize or even to oligomerize, spacing between actin filaments could be variable in size. |
| Links |
PubMed Online version:10.1074/jbc.M406797200 |
| Keywords |
Actin Cytoskeleton/chemistry; Actin Cytoskeleton/metabolism; Actins/chemistry; Actins/metabolism; Amino Acid Motifs; Amino Acid Sequence; Animals; Binding Sites; Biopolymers/chemistry; Biopolymers/metabolism; Dimerization; Manduca; Protein Binding; Protein Subunits/chemistry; Protein Subunits/metabolism; Vacuolar Proton-Translocating ATPases/chemistry; Vacuolar Proton-Translocating ATPases/metabolism |
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