Visual arrestin binding to microtubules involves a distinct conformational change. J Biol Chem 2006 Apr 07;281(14):9765-72
Date
02/08/2006Pubmed ID
16461350Pubmed Central ID
PMC2430877DOI
10.1074/jbc.M510738200Scopus ID
2-s2.0-33646942808 (requires institutional sign-in at Scopus site) 80 CitationsAbstract
Recently we found that visual arrestin binds microtubules and that this interaction plays an important role in arrestin localization in photoreceptor cells. Here we use site-directed mutagenesis and spin labeling to explore the molecular mechanism of this novel regulatory interaction. The microtubule binding site maps to the concave sides of the two arrestin domains, overlapping with the rhodopsin binding site, which makes arrestin interactions with rhodopsin and microtubules mutually exclusive. Arrestin interaction with microtubules is enhanced by several "activating mutations" and involves multiple positive charges and hydrophobic elements. The comparable affinity of visual arrestin for microtubules and unpolymerized tubulin (K(D) > 40 mum and >65 mum, respectively) suggests that the arrestin binding site is largely localized on the individual alphabeta-dimer. The changes in the spin-spin interaction of a double-labeled arrestin indicate that the conformation of microtubule-bound arrestin differs from that of free arrestin in solution. In sharp contrast to rhodopsin, where tight binding requires an extended interdomain hinge, arrestin binding to microtubules is enhanced by deletions in this region, suggesting that in the process of microtubule binding the domains may move in the opposite direction. Thus, microtubule and rhodopsin binding induce different conformational changes in arrestin, suggesting that arrestin assumes three distinct conformations in the cell, likely with different functional properties.
Author List
Hanson SM, Francis DJ, Vishnivetskiy SA, Klug CS, Gurevich VVAuthor
Candice S. Klug PhD Professor in the Biophysics department at Medical College of WisconsinMESH terms used to index this publication - Major topics in bold
ArrestinBinding Sites
Escherichia coli
Microtubules
Mutagenesis, Site-Directed
Protein Binding
Protein Conformation
Rhodopsin
Spin Labels
Structure-Activity Relationship
Tubulin
