4Z8G

Chimera of Tropomodulin-1 and Leiomodin-1 Actin-Binding Site 2 (TL1 ABS2)

Summary for 4Z8G

• Entry DOI: 10.2210/pdb4z8g/pdb
• Related: 4Z94
• Descriptor: Tropomodulin-1, Leiomodin-1 chimera (TP1 ABS2), NICKEL (II) ION (3 entities in total)
• Functional Keywords: actin nucleator, leucine rich repeat domain, protein binding
• Biological source: Homo sapiens (Human); More
• Total number of polymer chains: 1
• Total formula weight: 22322.30

Authors

Boczkowska, M.,Rebowski, G.,Dominguez, R. (deposition date: 2015-04-08, release date: 2015-10-21, Last modification date: 2023-09-27)

Primary citation

Boczkowska, M.,Rebowski, G.,Kremneva, E.,Lappalainen, P.,Dominguez, R.
How Leiomodin and Tropomodulin use a common fold for different actin assembly functions.
Nat Commun, 6:8314-8314, 2015

PubMed Abstract: How proteins sharing a common fold have evolved different functions is a fundamental question in biology. Tropomodulins (Tmods) are prototypical actin filament pointed-end-capping proteins, whereas their homologues, Leiomodins (Lmods), are powerful filament nucleators. We show that Tmods and Lmods do not compete biochemically, and display similar but distinct localization in sarcomeres. Changes along the polypeptide chains of Tmods and Lmods exquisitely adapt their functions for capping versus nucleation. Tmods have alternating tropomyosin (TM)- and actin-binding sites (TMBS1, ABS1, TMBS2 and ABS2). Lmods additionally contain a C-terminal extension featuring an actin-binding WH2 domain. Unexpectedly, the different activities of Tmods and Lmods do not arise from the Lmod-specific extension. Instead, nucleation by Lmods depends on two major adaptations-the loss of pointed-end-capping elements present in Tmods and the specialization of the highly conserved ABS2 for recruitment of two or more actin subunits. The WH2 domain plays only an auxiliary role in nucleation.

PubMed: 26370058
DOI: 10.1038/ncomms9314

Experimental method

X-RAY DIFFRACTION (2.1 Å)