PDBsum entry: 2nuu

Transport protein/signaling protein

PDB id: 2nuu

Contents

Protein chains

(+ 0 more) 409 a.a. *

(+ 0 more) 112 a.a. *

Ligands

ADP ×6

Waters ×550

* Residue conservation analysis

PDB id:

2nuu

Name:

Transport protein/signaling protein

Title:

Regulating the escherichia coli ammonia channel: the crystal structure of the amtb-glnk complex

Structure:

Ammonia channel. Chain: a, b, c, d, e, f. Synonym: ammonia transporter, amtb. Engineered: yes. Nitrogen regulatory protein p-ii 2. Chain: g, h, i, j, k, l. Synonym: glnk. Engineered: yes

Source:

Escherichia coli. Organism_taxid: 562. Strain: gt1000. Gene: amtb. Expressed in: escherichia coli. Expression_system_taxid: 562. Gene: glnk.

Biol. unit:

Hexamer (from PQS)

Resolution:

2.50Å R-factor: 0.175 R-free: 0.249

Authors:

M.J.Conroy,A.Durand,D.Lupo,X.-D.Li,P.A.Bullough,F.K.Winkler, M.Merrick

Key ref:

M.J.Conroy et al. (2007). The crystal structure of the Escherichia coli AmtB-GlnK complex reveals how GlnK regulates the ammonia channel. Proc Natl Acad Sci U S A, 104, 1213-1218. PubMed id: 17220269 DOI: 10.1073/pnas.0610348104

Date:

09-Nov-06 Release date: 21-Nov-06

Protein chains

P69681  (AMTB_ECOLI) -  Ammonia channel

Seq: 428 a.a.

Struc: 409 a.a.*

Protein chains

P0AC55  (GLNK_ECOLI) -  Nitrogen regulatory protein P-II 2

Seq: 112 a.a.

Struc: 112 a.a.

* PDB and UniProt seqs differ at 5 residue positions (black crosses)

 Gene Ontology (GO) functional annotation 

• Cellular component: membrane (3 terms)
• Biological process: transport (7 terms)
• Biochemical function: enzyme regulator activity (6 terms)

DOI no: 10.1073/pnas.0610348104

Proc Natl Acad Sci U S A 104:1213-1218 (2007)

PubMed id: 17220269

The crystal structure of the Escherichia coli AmtB-GlnK complex reveals how GlnK regulates the ammonia channel.

M.J.Conroy, A.Durand, D.Lupo, X.D.Li, P.A.Bullough, F.K.Winkler, M.Merrick.

ABSTRACT

Amt proteins are ubiquitous channels for the conduction of ammonia in archaea, eubacteria, fungi, and plants. In Escherichia coli, previous studies have indicated that binding of the PII signal transduction protein GlnK to the ammonia channel AmtB regulates the channel thereby controlling ammonium influx in response to the intracellular nitrogen status. Here, we describe the crystal structure of the complex between AmtB and GlnK at a resolution of 2.5 A. This structure of PII in a complex with one of its targets reveals physiologically relevant conformations of both AmtB and GlnK. GlnK interacts with AmtB almost exclusively via a long surface loop containing Y51 (T-loop), the tip of which inserts deeply into the cytoplasmic pore exit, blocking ammonia conduction. Y51 of GlnK is also buried in the pore exit, explaining why uridylylation of this residue prevents complex formation.

Selected figure(s)

Figure 1.
Fig. 1. Overview of the AmtB–GlnK complex. The surface of AmtB is shown, and GlnK is shown in cartoon representation. Each subunit of AmtB and GlnK is colored independently. (A) View from the cytoplasm along the threefold axis perpendicular to the membrane. (B) View in the membrane plane. All figures were made using PyMOL (40).

Figure 4.
Fig. 4. Stereo representation of the ADP binding site of GlnK. The difference electron density, contoured at 3 , was obtained after 20 cycles of restrained refinement with the ADP molecule omitted. Residues of the two GlnK subunits forming the binding site and ADP are shown in gray, cyan, and magenta ball-and-stick models, respectively. Hydrogen bonding interactions including one water molecule (pink sphere) are shown with dashed lines, and selected residues are labeled.

Figures were selected by an automated process.