Applewhite DA, Grode KD, Duncan MC, Rogers SL. The actin-microtubule cross-linking activity of Drosophila Short stop is regulated by intramolecular inhibition.
Mol Biol Cell 2013;
24:2885-93. [PMID:
23885120 PMCID:
PMC3771950 DOI:
10.1091/mbc.e12-11-0798]
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Abstract
The authors investigated the regulation of the Drosophila actin-microtubule cross-linker Short stop (Shot) and found that Shot undergoes an intramolecular conformational change that regulates its cross-linking activity. This intramolecular interaction depends on Shot's NH2-terminal actin-binding domain and EF-hand-GAS2 domain.
Actin and microtubule dynamics must be precisely coordinated during cell migration, mitosis, and morphogenesis—much of this coordination is mediated by proteins that physically bridge the two cytoskeletal networks. We have investigated the regulation of the Drosophila actin-microtubule cross-linker Short stop (Shot), a member of the spectraplakin family. Our data suggest that Shot's cytoskeletal cross-linking activity is regulated by an intramolecular inhibitory mechanism. In its inactive conformation, Shot adopts a “closed” conformation through interactions between its NH2-terminal actin-binding domain and COOH-terminal EF-hand-GAS2 domain. This inactive conformation is targeted to the growing microtubule plus end by EB1. On activation, Shot binds along the microtubule through its COOH-terminal GAS2 domain and binds to actin with its NH2-terminal tandem CH domains. We propose that this mechanism allows Shot to rapidly cross-link dynamic microtubules in response to localized activating signals at the cell cortex.
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