PDBsum entry 5a50

Lipid binding protein

PDB id: 5a50

Contents

Protein chains

165 a.a.

165 a.a.

Ligands

_PC ×2

Metals

_CA ×4

_ZN

Waters ×141

PDB id:

5a50

Name:

Lipid binding protein

Title:

The crystal structure of arabidopsis thaliana car4 in complex with two calcium ions, zn and phopho choline

Structure:

At3g17980. Chain: a. Synonym: car4. Engineered: yes. At3g17980. Chain: b. Synonym: car4. Engineered: yes

Source:

Arabidopsis thaliana. Thale cress. Organism_taxid: 3702. Expressed in: escherichia coli. Expression_system_taxid: 562. Expression_system_taxid: 562

Resolution:

2.40Å R-factor: 0.197 R-free: 0.245

Authors:

M.Diaz,A.Albert

Key ref:

M.Diaz et al. (2016). Calcium-dependent oligomerization of CAR proteins at cell membrane modulates ABA signaling. Proc Natl Acad Sci U S A, 113, E396. PubMed id: 26719420 DOI: 10.1073/pnas.1512779113

Date:

16-Jun-15 Release date: 02-Mar-16

Protein chain

Q9LVH4  (CAR4_ARATH) -  Protein C2-DOMAIN ABA-RELATED 4 from Arabidopsis thaliana

Seq: 177 a.a.

Struc: 165 a.a.*

Protein chain

Q9LVH4  (CAR4_ARATH) -  Protein C2-DOMAIN ABA-RELATED 4 from Arabidopsis thaliana

Seq: 177 a.a.

Struc: 167 a.a.*

* PDB and UniProt seqs differ at 3 residue positions (black crosses)

DOI no: 10.1073/pnas.1512779113

Proc Natl Acad Sci U S A 113:E396 (2016)

PubMed id: 26719420

Calcium-dependent oligomerization of CAR proteins at cell membrane modulates ABA signaling.

M.Diaz, M.J.Sanchez-Barrena, J.M.Gonzalez-Rubio, L.Rodriguez, D.Fernandez, R.Antoni, C.Yunta, B.Belda-Palazon, M.Gonzalez-Guzman, M.Peirats-Llobet, M.Menendez, J.Boskovic, J.A.Marquez, P.L.Rodriguez, A.Albert.

ABSTRACT

Regulation of ion transport in plants is essential for cell function. Abiotic stress unbalances cell ion homeostasis, and plants tend to readjust it, regulating membrane transporters and channels. The plant hormone abscisic acid (ABA) and the second messenger Ca(2+) are central in such processes, as they are involved in the regulation of protein kinases and phosphatases that control ion transport activity in response to environmental stimuli. The identification and characterization of the molecular mechanisms underlying the effect of ABA and Ca(2+) signaling pathways on membrane function are central and could provide opportunities for crop improvement. The C2-domain ABA-related (CAR) family of small proteins is involved in the Ca(2+)-dependent recruitment of the pyrabactin resistance 1/PYR1-like (PYR/PYL) ABA receptors to the membrane. However, to fully understand CAR function, it is necessary to define a molecular mechanism that integrates Ca(2+) sensing, membrane interaction, and the recognition of the PYR/PYL interacting partners. We present structural and biochemical data showing that CARs are peripheral membrane proteins that functionally cluster on the membrane and generate strong positive membrane curvature in a Ca(2+)-dependent manner. These features represent a mechanism for the generation, stabilization, and/or specific recognition of membrane discontinuities. Such structures may act as signaling platforms involved in the recruitment of PYR/PYL receptors and other signaling components involved in cell responses to stress.