Regulation of INF2-mediated actin polymerization through site-specific lysine acetylation of actin itself

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A , M , Fung , T S , Francomacaro , L M , Huynh , T , Kotila , T , Svindrych , Z & Higgs , H N 2020 , ' Regulation of INF2-mediated actin polymerization through site-specific lysine acetylation of actin itself ' , Proceedings of the National Academy of Sciences of the United States of America , vol. 117 , no. 1 , pp. 439-447 . https://doi.org/10.1073/pnas.1914072117

Title: Regulation of INF2-mediated actin polymerization through site-specific lysine acetylation of actin itself
Author: A, Mu; Fung, Tak Shun; Francomacaro, Lisa M.; Huynh, Thao; Kotila, Tommi; Svindrych, Zdenek; Higgs, Henry N.
Contributor organization: Institute of Biotechnology
Doctoral Programme in Integrative Life Science
Date: 2020-01-07
Language: eng
Number of pages: 9
Belongs to series: Proceedings of the National Academy of Sciences of the United States of America
ISSN: 0027-8424
DOI: https://doi.org/10.1073/pnas.1914072117
URI: http://hdl.handle.net/10138/317249
Abstract: INF2 is a formin protein that accelerates actin polymerization. A common mechanism for formin regulation is autoinhibition, through interaction between the N-terminal diaphanous inhibitory domain (DID) and C-terminal diaphanous autoregulatory domain (DAD). We recently showed that INF2 uses a variant of this mechanism that we term "facilitated autoinhibition," whereby a complex consisting of cyclase-associated protein (CAP) bound to lysine-acetylated actin (KAc-actin) is required for INF2 inhibition, in a manner requiring INF2-DID. Deacetylation of actin in the CAP/KAc-actin complex activates INF2. Here we use lysine-to-glutamine mutations as acetylmimetics to map the relevant lysines on actin for INF2 regulation, focusing on K50, K61, and K328. Biochemically, K50Q- and K61Q-actin, when bound to CAP2, inhibit full-length INF2 but not INF2 lacking DID. When not bound to CAP, these mutant actins polymerize similarly to WT-actin in the presence or absence of INF2, suggesting that the effect of the mutation is directly on INF2 regulation. In U2OS cells, K50Q- and K61Q-actin inhibit INF2-mediated actin polymerization when expressed at low levels. Direct-binding studies show that the CAP WH2 domain binds INF2-DID with submicromolar affinity but has weak affinity for actin monomers, while INF2-DAD binds CAP/K50Q-actin 5-fold better than CAP/WT-actin. Actin in complex with full-length CAP2 is predominately ATP-bound. These interactions suggest an inhibition model whereby CAP/KAc-actin serves as a bridge between INF2 DID and DAD. In U2OS cells, INF2 is 90-fold and 5-fold less abundant than CAP1 and CAP2, respectively, suggesting that there is sufficient CAP for full INF2 inhibition.
Subject: ADP-ACTIN
COFILIN
CYCLASE-ASSOCIATED PROTEIN
INF2
INVERTED FORMIN 2
LEVEL
MECHANISM
MONOMERS
NUCLEATION
U2OS
WH2 DOMAIN
WH2 motif
cyclase-associated protein
mitochondria
nucleation
1182 Biochemistry, cell and molecular biology
Peer reviewed: Yes
Rights: unspecified
Usage restriction: openAccess
Self-archived version: acceptedVersion


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