PDBsum entry 5af1

Transport protein

PDB id: 5af1

Contents

Protein chains

450 a.a.

Waters ×536

PDB id:

5af1

Name:

Transport protein

Title:

Crystal structure of candida albicans mep2

Structure:

Mep2. Chain: a, b. Engineered: yes

Source:

Candida albicans. Organism_taxid: 5476. Expressed in: saccharomyces cerevisiae. Expression_system_taxid: 4932.

Resolution:

1.64Å R-factor: 0.137 R-free: 0.159

Authors:

J.C.Rutherford,A.Chembath,B.Van Den Berg

Key ref:

B.van den Berg et al. (2016). Structural basis for Mep2 ammonium transceptor activation by phosphorylation. Nat Commun, 7, 11337. PubMed id: 27088325 DOI: 10.1038/ncomms11337

Date:

14-Jan-15 Release date: 27-Jan-16

Protein chains

Q59UP8  (Q59UP8_CANAL) -  Ammonium transporter from Candida albicans (strain SC5314 / ATCC MYA-2876)

Seq: 480 a.a.

Struc: 450 a.a.*

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

DOI no: 10.1038/ncomms11337

Nat Commun 7:11337 (2016)

PubMed id: 27088325

Structural basis for Mep2 ammonium transceptor activation by phosphorylation.

B.van den Berg, A.Chembath, D.Jefferies, A.Basle, S.Khalid, J.C.Rutherford.

ABSTRACT

Mep2 proteins are fungal transceptors that play an important role as ammonium sensors in fungal development. Mep2 activity is tightly regulated by phosphorylation, but how this is achieved at the molecular level is not clear. Here we report X-ray crystal structures of the Mep2 orthologues from Saccharomyces cerevisiae and Candida albicans and show that under nitrogen-sufficient conditions the transporters are not phosphorylated and present in closed, inactive conformations. Relative to the open bacterial ammonium transporters, non-phosphorylated Mep2 exhibits shifts in cytoplasmic loops and the C-terminal region (CTR) to occlude the cytoplasmic exit of the channel and to interact with His2 of the twin-His motif. The phosphorylation site in the CTR is solvent accessible and located in a negatively charged pocket ∼30 Å away from the channel exit. The crystal structure of phosphorylation-mimicking Mep2 variants from C. albicans show large conformational changes in a conserved and functionally important region of the CTR. The results allow us to propose a model for regulation of eukaryotic ammonium transport by phosphorylation.