Intrastrand cross-linked actin between Gln-41 and Cys-374. II. Properties of cross-linked oligomers

Eldar Kim, Martin Phillips, György Hegyi, Andras Mühlrad, Emil Reisler*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

24 Scopus citations

Abstract

Actin filaments partially cross-linked with ANP (N-(4-azido-2- nitrophenyl)-putrescine between Gln-41 and Cys-374 on adjacent monomers in the long-pitch helix were depolymerized and fractionated into pools of longitudinal cross-linked dimers (s°20,w = 5.55 ± 0.22 s), trimers (s°20,w = 6.93 ± 0.12 S), and higher-order oligomers. Competition binding experiments of myosin subfragment (S1) to cross-linked dimers in the presence of pyrenyl G-actin revealed about 2 orders of magnitude stronger binding of the first than that of the second S1 molecule to actin dimer. Under similar conditions the unpolymerized cross-linked actin species activated the MgATPase of S1 only severalfold compared to 70-fold activation by F-actin. The cross-linked dimers, trimers, and oligomers were polymerized into filaments by MgCl2 faster than un-cross-linked actin. In electron micrographs these filaments appeared sometimes shorter and had greater tendency to bend than un-cross-linked actin filaments. Small amounts of cross-linked actin dimers nucleated S1-induced polymerization of actin, but the polymerization by S1 was inhibited for pure populations of cross-linked dimers, trimers, and oligomers. The cross-linked dimers did not decrease the kinetic difference between the polymerization of actin by S1 isozymes S1 (A1) and S1(A2). According to electron microscopy evidence, cross-linked actin oligomers polymerized by S1 yielded much shorter arrowhead structures than the un-cross-linked actin. These results indicate the importance of lateral actin-actin interaction for the activation of myosin ATPase and the polymerization of actin by S1.

Original languageEnglish
Pages (from-to)17793-17800
Number of pages8
JournalBiochemistry
Volume37
Issue number51
DOIs
StatePublished - 22 Dec 1998

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