PDBsum entry 6vec

Protein fibril

PDB id: 6vec

Contents

Protein chains

(+ 5 more) 370 a.a.

(+ 5 more) 241 a.a.

Ligands

ADP ×11

Metals

_MG ×11

PDB id:

6vec

Name:

Protein fibril

Title:

Cryo-em structure of f-actin/plastin2-abd2 complex

Structure:

Actin, alpha skeletal muscle. Chain: a, b, c, d, e, f, g, h, i, j, k. Synonym: alpha-actin-1. Lcp1. Chain: a, b, c, d, e, f, g, h, i, j, k. Fragment: unp residues 385-625. Engineered: yes

Source:

Oryctolagus cuniculus. Rabbit. Organism_taxid: 9986. Homo sapiens. Human. Organism_taxid: 9606. Gene: hel-s-37. Expressed in: escherichia coli 'bl21-gold(de3)plyss ag'. Expression_system_taxid: 866768

Authors:

W.Zheng,D.S.Kudryashov,E.H.Egelman

Key ref:

C.L.Schwebach et al. (2020). Osteogenesis imperfecta mutations in plastin 3 lead to impaired calcium regulation of actin bundling. Bone Res, 8, 21. PubMed id: 32509377 DOI: 10.1038/s41413-020-0095-2

Date:

31-Dec-19 Release date: 09-Dec-20

Protein chains

P68135  (ACTS_RABIT) -  Actin, alpha skeletal muscle from Oryctolagus cuniculus

Seq: 377 a.a.

Struc: 370 a.a.

Protein chains

P13796  (PLSL_HUMAN) -  Plastin-2 from Homo sapiens

Seq: 627 a.a.

Struc: 241 a.a.*

* PDB and UniProt seqs differ at 1 residue position (black cross)

Enzyme reactions

• Enzyme class: Chains A, B, C, D, E, F, G, H, I, J, K: E.C.3.6.4.- - ?????

DOI no: 10.1038/s41413-020-0095-2

Bone Res 8:21 (2020)

PubMed id: 32509377

Osteogenesis imperfecta mutations in plastin 3 lead to impaired calcium regulation of actin bundling.

C.L.Schwebach, E.Kudryashova, W.Zheng, M.Orchard, H.Smith, L.A.Runyan, E.H.Egelman, D.S.Kudryashov.

ABSTRACT

Mutations in actin-bundling protein plastin 3 (PLS3) emerged as a cause of congenital osteoporosis, but neither the role of PLS3 in bone development nor the mechanisms underlying PLS3-dependent osteoporosis are understood. Of the over 20 identified osteoporosis-linked PLS3 mutations, we investigated all five that are expected to produce full-length protein. One of the mutations distorted an actin-binding loop in the second actin-binding domain of PLS3 and abolished F-actin bundling as revealed by cryo-EM reconstruction and protein interaction assays. Surprisingly, the remaining four mutants fully retained F-actin bundling ability. However, they displayed defects in Ca²⁺ sensitivity: two of the mutants lost the ability to be inhibited by Ca²⁺, while the other two became hypersensitive to Ca²⁺. Each group of the mutants with similar biochemical properties showed highly characteristic cellular behavior. Wild-type PLS3 was distributed between lamellipodia and focal adhesions. In striking contrast, the Ca²⁺-hyposensitive mutants were not found at the leading edge but localized exclusively at focal adhesions/stress fibers, which displayed reinforced morphology. Consistently, the Ca²⁺-hypersensitive PLS3 mutants were restricted to lamellipodia, while chelation of Ca²⁺ caused their redistribution to focal adhesions. Finally, the bundling-deficient mutant failed to co-localize with any F-actin structures in cells despite a preserved F-actin binding through a non-mutation-bearing actin-binding domain. Our findings revealed that severe osteoporosis can be caused by a mutational disruption of the Ca²⁺-controlled PLS3's cycling between adhesion complexes and the leading edge. Integration of the structural, biochemical, and cell biology insights enabled us to propose a molecular mechanism of plastin activity regulation by Ca²⁺.