PDBsum entry 7krb

Membrane protein

PDB id: 7krb

Contents

Protein chain

138 a.a.

PDB id:

7krb

Name:

Membrane protein

Title:

Solution structure of the dysferlin c2a domain in its calcium-bound state

Structure:

Isoform 15 of dysferlin. Chain: a. Synonym: dystrophy-associated fer-1-like protein,fer-1-like protein 1. Engineered: yes

Source:

Homo sapiens. Human. Organism_taxid: 9606. Gene: dysf, fer1l1. Expressed in: escherichia coli bl21. Expression_system_taxid: 511693.

NMR struc:

20 models

Authors:

Y.Wang,P.Mercier,L.Santamaria,G.S.Shaw

Key ref:

Y.Wang et al. (2021). Calcium binds and rigidifies the dysferlin C2A domain in a tightly coupled manner. Biochem J, 478, 197-215. PubMed id: 33449082 DOI: 10.1042/BCJ20200773

Date:

19-Nov-20 Release date: 27-Jan-21

Protein chain

O75923  (DYSF_HUMAN) -  Dysferlin from Homo sapiens

Seq: 2080 a.a.

Struc: 138 a.a.*

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

Enzyme reactions

• Enzyme class: E.C.?

DOI no: 10.1042/BCJ20200773

Biochem J 478:197-215 (2021)

PubMed id: 33449082

Calcium binds and rigidifies the dysferlin C2A domain in a tightly coupled manner.

Y.Wang, R.Tadayon, L.Santamaria, P.Mercier, C.J.Forristal, G.S.Shaw.

ABSTRACT

The membrane protein dysferlin (DYSF) is important for calcium-activated plasma membrane repair, especially in muscle fibre cells. Nearly 600 mutations in the DYSF gene have been identified that are causative for rare genetic forms of muscular dystrophy. The dysferlin protein consists of seven C2 domains (C2A-C2G, 13%-33% identity) used to recruit calcium ions and traffic accessory proteins and vesicles to injured membrane sites needed to reseal a wound. Amongst these, the C2A is the most prominent facilitating the calcium-sensitive interaction with membrane surfaces. In this work, we determined the calcium-free and calcium-bound structures of the dysferlin C2A domain using NMR spectroscopy and X-ray crystallography. We show that binding two calcium ions to this domain reduces the flexibility of the Ca2+-binding loops in the structure. Furthermore, calcium titration and mutagenesis experiments reveal the tight coupling of these calcium-binding sites whereby the elimination of one site abolishes calcium binding to its partner site. We propose that the electrostatic potential distributed by the flexible, negatively charged calcium-binding loops in the dysferlin C2A domain control first contact with calcium that promotes subsequent binding. Based on these results, we hypothesize that dysferlin uses a 'calcium-catching' mechanism to respond to calcium influx during membrane repair.