Journal article
Two Deafness-causing (DFNA20/26) Actin Mutations Affect Arp2/3-dependent Actin Regulation
The Journal of biological chemistry, Vol.287(32), pp.27217-27226
08/03/2012
DOI: 10.1074/jbc.M112.377283
PMCID: PMC3411063
PMID: 22718764
Abstract
Background:
K118(M/N) γ-actin mutations cause deafness, which indicates that they negatively affect actin structure and/or dynamics.
Results:
Both mutations alter actin regulation by Arp2/3.
Conclusion:
Lys-118 serves an important role in intra- and intermonomer interactions and in actin network regulation by binding proteins.
Significance:
Lys-118 may play a more significant role in the internal allostery of the actin structure than previously believed.
Hearing requires proper function of the auditory hair cell, which is critically dependent upon its actin-based cytoskeletal structure. Currently, ten point mutations in nonmuscle γ-actin have been identified as causing progressive autosomal dominant nonsyndromic hearing loss (DFNA20/26), highlighting these ten residues as functionally important to actin structure and/or regulation. Two of the mutations, K118M and K118N, are located near the putative binding site for the ubiquitously expressed Arp2/3 complex. We therefore hypothesized that these mutations may affect Arp2/3-dependent regulation of the actin cytoskeleton. Using
in vitro
bulk polymerization assays, we show that the Lys-118 mutations notably reduce actin + Arp2/3 polymerization rates compared with WT. Further
in vitro
analysis of the K118M mutant using TIRF microscopy indicates the actual number of branches formed per filament is reduced compared with WT and, surprisingly, branch location is altered such that the majority of K118M branches form near the pointed end of the filament. These results highlight a previously unknown role for the Lys-118 residue in the actin-Arp2/3 interaction and also further suggest that Lys-118 may play a more significant role in intra- and intermonomer interactions than was initially hypothesized.
Details
- Title: Subtitle
- Two Deafness-causing (DFNA20/26) Actin Mutations Affect Arp2/3-dependent Actin Regulation
- Creators
- Karina A Kruth - From the Department of Biochemistry, University of Iowa Carver College of Medicine, Iowa City, Iowa 52242-1109Peter A Rubenstein - From the Department of Biochemistry, University of Iowa Carver College of Medicine, Iowa City, Iowa 52242-1109
- Resource Type
- Journal article
- Publication Details
- The Journal of biological chemistry, Vol.287(32), pp.27217-27226
- DOI
- 10.1074/jbc.M112.377283
- PMID
- 22718764
- PMCID
- PMC3411063
- NLM abbreviation
- J Biol Chem
- ISSN
- 0021-9258
- eISSN
- 1083-351X
- Publisher
- American Society for Biochemistry and Molecular Biology; 9650 Rockville Pike, Bethesda, MD 20814, U.S.A
- Grant note
- DC008803 / National Institutes of Health
- Alternative title
- Actin Deafness Mutations and Arp2/3
- Language
- English
- Date published
- 08/03/2012
- Academic Unit
- Psychiatry; Stead Family Department of Pediatrics; Biochemistry and Molecular Biology; Internal Medicine
- Record Identifier
- 9984024404802771
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