PDBsum entry 4n5x

Calcium-binding protein

PDB id: 4n5x

Contents

Protein chain

155 a.a.

Ligands

PEG

Metals

_CA ×5

Waters ×124

PDB id:

4n5x

Name:

Calcium-binding protein

Title:

Crystal structure of n-terminal calmodulin-like calcium sensor of human mitochondrial atp-mg/pi carrier scamc1

Structure:

Calcium-binding mitochondrial carrier protein scamc-1. Chain: a. Fragment: unp residues 1-193. Synonym: mitochondrial atp-mg/pi carrier protein 1, mitochondrial ca(2+)-dependent solute carrier protein 1, small calcium-binding mitochondrial carrier protein 1, solute carrier family 25 member 24. Engineered: yes. Mutation: yes

Source:

Homo sapiens. Human. Organism_taxid: 9606. Gene: slc25a24, apc1, mcsc1, scamc1. Expressed in: escherichia coli. Expression_system_taxid: 562

Resolution:

2.10Å R-factor: 0.182 R-free: 0.225

Authors:

Q.Yang,S.Bruschweiler,J.Chou

Key ref:

Q.Yang et al. (2014). A self-sequestered calmodulin-like Ca²⁺ sensor of mitochondrial SCaMC carrier and its implication to Ca²⁺-dependent ATP-Mg/P(i) transport. Structure, 22, 209-217. PubMed id: 24332718 DOI: 10.1016/j.str.2013.10.018

Date:

10-Oct-13 Release date: 18-Dec-13

Protein chain

Q6NUK1  (SCMC1_HUMAN) -  Mitochondrial adenyl nucleotide antiporter SLC25A24 from Homo sapiens

Seq: 477 a.a.

Struc: 155 a.a.

Enzyme reactions

• Enzyme class: E.C.?

DOI no: 10.1016/j.str.2013.10.018

Structure 22:209-217 (2014)

PubMed id: 24332718

A self-sequestered calmodulin-like Ca²⁺ sensor of mitochondrial SCaMC carrier and its implication to Ca²⁺-dependent ATP-Mg/P(i) transport.

Q.Yang, S.Brüschweiler, J.J.Chou.

ABSTRACT

The mitochondrial carriers play essential roles in energy metabolism. The short Ca(2+)-binding mitochondrial carrier (SCaMC) transports ATP-Mg in exchange for Pi and is important for activities that depend on adenine nucleotides. SCaMC adopts, in addition to the transmembrane domain (TMD) that transports solutes, an extramembrane N-terminal domain (NTD) that regulates solute transport in a Ca(2+)-dependent manner. Crystal structure of the Ca(2+)-bound NTD reveals a compact architecture in which the functional EF hands are sequestered by an endogenous helical segment. Nuclear magnetic resonance (NMR) relaxation rates indicated that removal of Ca(2+) from NTD results in a major conformational switch from the rigid and compact Ca(2+)-bound state to the dynamic and loose apo state. Finally, we showed using surface plasmon resonance and NMR titration experiments that free apo NTDs could specifically interact with liposome-incorporated TMD, but that Ca(2+) binding drastically weakened the interaction. Our results together provide a molecular explanation for Ca(2+)-dependent ATP-Mg flux in mitochondria.