GltA

• Description: large subunit of glutamate synthase
  
  

Gene name	gltA
Synonyms
Essential	no
Product	glutamate synthase (large subunit)
Function	glutamate biosynthesis
Interactions involving this protein in SubtInteract: GltA
Metabolic function and regulation of this protein in SubtiPathways: Ammonium/ glutamate
MW, pI	168 kDa, 5.47
Gene length, protein length	4560 bp, 1520 amino acids
Immediate neighbours	gltB, gltC
Get the DNA and protein sequences (Barbe et al., 2009)
Genetic context This image was kindly provided by SubtiList
Expression at a glance   PubMed

Categories containing this gene/protein

biosynthesis/ acquisition of amino acids, membrane proteins, phosphoproteins

This gene is a member of the following regulons

GltC regulon, FsrA regulon, TnrA regulon

The gene

Basic information

• Locus tag: BSU18450

Phenotypes of a mutant

auxotrophic for glutamate

Database entries

• DBTBS entry: [1]

• SubtiList entry: [2]

The protein

Basic information/ Evolution

• Catalyzed reaction/ biological activity: 2 L-glutamate + NADP⁺ = L-glutamine + 2-oxoglutarate + NADPH (according to Swiss-Prot) 2 L-glutamate + NADP(+) <=> L-glutamine + 2-oxoglutarate + NADPH

• Protein family: glutamate synthase family (according to Swiss-Prot) glutamate synthase family

• Paralogous protein(s): YerD

Extended information on the protein

• Kinetic information:

• Domains:
  • Glutamine amidotransferase type-2 domain (22-415)
  • Nucleotide binding domain (1060-1112)

• Modification:

• Cofactor(s): 3Fe-4S, FAD, FMN

• Effectors of protein activity:

• Interactions:
  • GltA-GltB PubMed
  • GltA-Icd PubMed

• Localization: membrane associated PubMed, cytoplasm

Database entries

• Structure: 2VDC (the GltA-GltB complex of Azospirillum brasiliense) PubMed

• UniProt: P39812

• KEGG entry: [3]

• E.C. number: 1.4.1.13 3 1.4.1.13]

Additional information

subject to Clp-dependent proteolysis upon glucose starvation PubMed

Expression and regulation

• Operon: gltA-gltB PubMed

• Expression browser: gltA PubMed

• Sigma factor: SigA PubMed

• Regulation:
  • expression activated by glucose (11 fold) (CcpA, GltC) PubMed
  • repressed by arginine (GltC, RocG) PubMed
  • expressed in the presence of ammonium PubMed
  • repressed in the absence of good nitrogen sources (glutamine or ammonium) (TnrA) PubMed
  • part of the iron sparing response, strong down-regulation in a fur mutant (Fur, FsrA) PubMed

• Regulatory mechanism:
  • GltC: transcription activation PubMed
  • TnrA: transcription repression PubMed
  • Fur: indirect effect via control of fsrA expression PubMed
  • FsrA: translation inhibition PubMed

• Additional information: subject to Clp-dependent proteolysis upon glucose starvation PubMed

Biological materials

• Mutant: GP807 (del gltAB::tet), GP222 (gltA under the control of p-xyl), available in Stülke lab

• Expression vector:

• lacZ fusion: pGP526 (in pAC7), pGP919 (in pAC5), available in Stülke lab

• GFP fusion:

• two-hybrid system: B. pertussis adenylate cyclase-based bacterial two hybrid system (BACTH), available in Stülke lab

• Antibody:

Labs working on this gene/protein

Linc Sonenshein, Tufts University, Boston, MA, USA Homepage

Jörg Stülke, University of Göttingen, Germany Homepage

References

Reviews

Akira Suzuki, David B Knaff
Glutamate synthase: structural, mechanistic and regulatory properties, and role in the amino acid metabolism.
Photosynth Res: 2005, 83(2);191-217
[PubMed:16143852] [WorldCat.org] [DOI] (P p)

Frank M Raushel, James B Thoden, Hazel M Holden
Enzymes with molecular tunnels.
Acc Chem Res: 2003, 36(7);539-48
[PubMed:12859215] [WorldCat.org] [DOI] (P p)