PDBsum entry 3la7

Transcription

PDB id: 3la7

Contents

Protein chains

209 a.a. *

Ligands

BOG

Waters ×170

* Residue conservation analysis

PDB id:

3la7

Name:

Transcription

Title:

Crystal structure of ntca in apo-form

Structure:

Global nitrogen regulator. Chain: a, b. Synonym: DNA-binding protein vf1, nitrogen-responsive regulatory protein. Engineered: yes

Source:

Anabaena. Organism_taxid: 103690. Strain: pcc 7120. Gene: alr4392, bifa, ntca. Expressed in: escherichia coli. Expression_system_taxid: 562.

Resolution:

1.90Å R-factor: 0.217 R-free: 0.264

Authors:

M.X.Zhao,Y.L.Jiang,Y.X.He,Y.F.Chen,Y.B.Teng,C.C.Zhang,Y.X.Chen, C.Z.Zhou

Key ref:

M.X.Zhao et al. (2010). Structural basis for the allosteric control of the global transcription factor NtcA by the nitrogen starvation signal 2-oxoglutarate. Proc Natl Acad Sci U S A, 107, 12487-12492. PubMed id: 20616047

Date:

06-Jan-10 Release date: 01-Sep-10

Protein chains

P0A4U6  (NTCA_NOSS1) -  Global nitrogen regulator from Nostoc sp. (strain PCC 7120 / SAG 25.82 / UTEX 2576)

Seq: 223 a.a.

Struc: 209 a.a.

Enzyme reactions

• Enzyme class: E.C.?

Proc Natl Acad Sci U S A 107:12487-12492 (2010)

PubMed id: 20616047

Structural basis for the allosteric control of the global transcription factor NtcA by the nitrogen starvation signal 2-oxoglutarate.

M.X.Zhao, Y.L.Jiang, Y.X.He, Y.F.Chen, Y.B.Teng, Y.Chen, C.C.Zhang, C.Z.Zhou.

ABSTRACT

2-oxogluatarate (2-OG), a metabolite of the highly conserved Krebs cycle, not only plays a critical role in metabolism, but also constitutes a signaling molecule in a variety of organisms ranging from bacteria to plants and animals. In cyanobacteria, the accumulation of 2-OG constitutes the signal of nitrogen starvation and NtcA, a global transcription factor, has been proposed as a putative receptor for 2-OG. Here we present three crystal structures of NtcA from the cyanobacterium Anabaena: the apoform, and two ligand-bound forms in complex with either 2-OG or its analogue 2,2-difluoropentanedioic acid. All structures assemble as homodimers, with each subunit composed of an N-terminal effector-binding domain and a C-terminal DNA-binding domain connected by a long helix (C-helix). The 2-OG binds to the effector-binding domain at a pocket similar to that used by cAMP in catabolite activator protein, but with a different pattern. Comparative structural analysis reveals a putative signal transmission route upon 2-OG binding. A tighter coiled-coil conformation of the two C-helices induced by 2-OG is crucial to maintain the proper distance between the two F-helices for DNA recognition. Whereas catabolite activator protein adopts a transition from off-to-on state upon cAMP binding, our structural analysis explains well why NtcA can bind to DNA even in its apoform, and how 2-OG just enhances the DNA-binding activity of NtcA. These findings provided the structural insights into the function of a global transcription factor regulated by 2-OG, a metabolite standing at a crossroad between carbon and nitrogen metabolisms.