2HMP

Uncomplexed actin cleaved with protease ECP32

Summary for 2HMP

• Entry DOI: 10.2210/pdb2hmp/pdb
• Descriptor: actin, alpha skeletal muscle, STRONTIUM ION, SPERMIDINE, ... (7 entities in total)
• Functional Keywords: actin polymerization; ecp32 protease; g-actin; f-actin, structural protein
• Biological source: Oryctolagus cuniculus (rabbit)
• Cellular location: Cytoplasm, cytoskeleton: P68135
• Total number of polymer chains: 2
• Total formula weight: 86381.20

Authors

Klenchin, V.A.,Khaitlina, S.Y.,Rayment, I. (deposition date: 2006-07-11, release date: 2006-09-19, Last modification date: 2023-08-30)

Primary citation

Klenchin, V.A.,Khaitlina, S.Y.,Rayment, I.
Crystal structure of polymerization-competent actin
J.Mol.Biol., 362:140-150, 2006

PubMed Abstract: All actin crystal structures reported to date represent actin complexed or chemically modified with molecules that prevent its polymerization. Actin cleaved with ECP32 protease at a single site between Gly42 and Val43 is virtually non-polymerizable in the Ca-ATP bound form but remains polymerization-competent in the Mg-bound form. Here, a crystal structure of the true uncomplexed ECP32-cleaved actin (ECP-actin) solved to 1.9 A resolution is reported. In contrast to the much more open conformation of the ECP-actin's nucleotide binding cleft in solution, the crystal structure of uncomplexed ECP-actin contains actin in a typical closed conformation similar to the complexed actin structures. This unambiguously demonstrates that the overall structure of monomeric actin is not significantly affected by a multitude of actin-binding proteins and toxins. The invariance of actin crystal structures suggests that the salt and precipitants necessary for crystallization stabilize actin in only one of its possible conformations. The asymmetric unit cell contains a new type of antiparallel actin dimer that may correspond to the "lower dimer" implicated in F-actin nucleation and branching. In addition, symmetry-related actin-actin contacts form a head to tail dimer that is strikingly similar to the longitudinal dimer predicted by the Holmes F-actin model, including a rotation of the monomers relative to each other not observed previously in actin crystal structures.

PubMed: 16893553
DOI: 10.1016/j.jmb.2006.07.001

Experimental method

X-RAY DIFFRACTION (1.899 Å)