GltA

• Description: large subunit of glutamate synthase
  
  

Gene name	gltA
Synonyms
Essential	no
Product	glutamate synthase (large subunit)
Function	glutamate biosynthesis
Gene expression levels in SubtiExpress: gltA
Interactions involving this protein in SubtInteract: GltA
Metabolic function and regulation of this protein in SubtiPathways: gltA
MW, pI	168 kDa, 5.47
Gene length, protein length	4560 bp, 1520 amino acids
Immediate neighbours	gltB, gltC
Sequences	Protein DNA DNA_with_flanks
Genetic context This image was kindly provided by SubtiList
Expression at a glance   PubMed

Categories containing this gene/protein

biosynthesis/ acquisition of amino acids, glutamate metabolism, membrane proteins, phosphoproteins

This gene is a member of the following regulons

GltC regulon, FsrA regulon, TnrA regulon, Efp-dependent proteins

The gene

Basic information

• Locus tag: BSU18450

Phenotypes of a mutant

auxotrophic for glutamate

Database entries

• BsubCyc: BSU18450

• 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:
  • phosphorylated on Arg-904 AND/OR Arg-914 PubMed

• Cofactor(s): 3Fe-4S, FAD, FMN

• Effectors of protein activity:

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

• Localization:
  • membrane associated PubMed, cytoplasm

Database entries

• BsubCyc: BSU18450

• 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
• translation is likely to require Efp due to the presence of several consecutive proline residues 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
  • translation is likely to require Efp due to the presence of several consecutive proline residues PubMed
  • number of protein molecules per cell (minimal medium with glucose and ammonium): 2409 PubMed
  • number of protein molecules per cell (minimal medium with glucose and ammonium, exponential phase): 609 PubMed
  • number of protein molecules per cell (minimal medium with glucose and ammonium, early stationary phase after glucose exhaustion): 285 PubMed
  • number of protein molecules per cell (minimal medium with glucose and ammonium, late stationary phase after glucose exhaustion): 104 PubMed

Biological materials

• Mutant: GP807 (del gltAB::tet), GP222 (gltA under the control of p-xyl), available in Stülke lab
  • 1A808 ( gltA::cat), PubMed, available at BGSC
  • 1A809 ( gltA::kan), PubMed, available at BGSC

• 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

Fabian Commichau University of Göttingen, Germany Homepage

References

Reviews

Katrin Gunka, Fabian M Commichau
Control of glutamate homeostasis in Bacillus subtilis: a complex interplay between ammonium assimilation, glutamate biosynthesis and degradation.
Mol Microbiol: 2012, 85(2);213-24
[PubMed:22625175] [WorldCat.org] [DOI] (I p)

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)