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Title: A CapG Gain-of-Function Mutant Reveals Critical Structure and Functional Determinants for Actin Filament Severing

Abstract

CapG is the only member of the gelsolin family unable to sever actin filaments. Changing amino acids 84-91 (severing domain) and 124-137 (WH2-containing segment) simultaneously to the sequences of gelsolin results in a mutant, CapG-sev, capable of severing actin filaments. The gain of severing function does not alter actin filament capping, but is accompanied by a higher affinity for monomeric actin, and the capacity to bind and sequester two actin monomers. Analysis of CapG-sev crystal structure suggests a more loosely folded inactive conformation than gelsolin, with a shorter S1-S2 latch. Calcium binding to S1 opens this latch and S1 becomes separated from a closely interfaced S2-S3 complex by an extended arm consisting of amino acids 118-137. Modeling with F-actin predicts that the length of this WH2-containing arm is critical for severing function, and the addition of a single amino acid (alanine or histidine) eliminates CapG-sev severing activity, confirming this prediction. We conclude that efficient severing utilizes two actin monomer-binding sites, and that the length of the WH2-containing segment is a critical functional determinant for severing.

Authors:
; ; ; ; ; ; ; ; ;
Publication Date:
Research Org.:
Brookhaven National Laboratory (BNL) National Synchrotron Light Source
Sponsoring Org.:
Doe - Office Of Science
OSTI Identifier:
930249
Report Number(s):
BNL-80940-2008-JA
Journal ID: ISSN 0261-4189; EMJODG; TRN: US200822%%1421
DOE Contract Number:  
DE-AC02-98CH10886
Resource Type:
Journal Article
Resource Relation:
Journal Name: EMBO Journal; Journal Volume: 25
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; ACTIN; AFFINITY; AMINO ACIDS; ARMS; CALCIUM; CAPACITY; CRYSTAL STRUCTURE; FILAMENTS; FORECASTING; FUNCTIONALS; FUNCTIONS; GAIN; HISTIDINE; LENGTH; MONOMERS; MUTANTS; SIMULATION; national synchrotron light source

Citation Formats

Zhang,Y., Vorobiev, S., Gibson, B., Hao, B., Dishu, G., Mishra, V., Yarmola, E., Bubb, M., Almo, S., and Southwick, F. A CapG Gain-of-Function Mutant Reveals Critical Structure and Functional Determinants for Actin Filament Severing. United States: N. p., 2006. Web. doi:10.1038/sj.emboj.7601323.
Zhang,Y., Vorobiev, S., Gibson, B., Hao, B., Dishu, G., Mishra, V., Yarmola, E., Bubb, M., Almo, S., & Southwick, F. A CapG Gain-of-Function Mutant Reveals Critical Structure and Functional Determinants for Actin Filament Severing. United States. doi:10.1038/sj.emboj.7601323.
Zhang,Y., Vorobiev, S., Gibson, B., Hao, B., Dishu, G., Mishra, V., Yarmola, E., Bubb, M., Almo, S., and Southwick, F. Sun . "A CapG Gain-of-Function Mutant Reveals Critical Structure and Functional Determinants for Actin Filament Severing". United States. doi:10.1038/sj.emboj.7601323.
@article{osti_930249,
title = {A CapG Gain-of-Function Mutant Reveals Critical Structure and Functional Determinants for Actin Filament Severing},
author = {Zhang,Y. and Vorobiev, S. and Gibson, B. and Hao, B. and Dishu, G. and Mishra, V. and Yarmola, E. and Bubb, M. and Almo, S. and Southwick, F.},
abstractNote = {CapG is the only member of the gelsolin family unable to sever actin filaments. Changing amino acids 84-91 (severing domain) and 124-137 (WH2-containing segment) simultaneously to the sequences of gelsolin results in a mutant, CapG-sev, capable of severing actin filaments. The gain of severing function does not alter actin filament capping, but is accompanied by a higher affinity for monomeric actin, and the capacity to bind and sequester two actin monomers. Analysis of CapG-sev crystal structure suggests a more loosely folded inactive conformation than gelsolin, with a shorter S1-S2 latch. Calcium binding to S1 opens this latch and S1 becomes separated from a closely interfaced S2-S3 complex by an extended arm consisting of amino acids 118-137. Modeling with F-actin predicts that the length of this WH2-containing arm is critical for severing function, and the addition of a single amino acid (alanine or histidine) eliminates CapG-sev severing activity, confirming this prediction. We conclude that efficient severing utilizes two actin monomer-binding sites, and that the length of the WH2-containing segment is a critical functional determinant for severing.},
doi = {10.1038/sj.emboj.7601323},
journal = {EMBO Journal},
number = ,
volume = 25,
place = {United States},
year = {Sun Jan 01 00:00:00 EST 2006},
month = {Sun Jan 01 00:00:00 EST 2006}
}