GlnA

• Description: trigger enzyme: glutamine synthetase and effector of TnrA and GlnR
  
  

Gene name	glnA
Synonyms
Essential	no
Product	trigger enzyme: glutamine synthetase
Function	glutamine biosynthesis, control of TnrA and GlnR activity
Metabolic function and regulation of this protein in SubtiPathways: Ammonium/ glutamate
MW, pI	50 kDa, 4.874
Gene length, protein length	1332 bp, 444 aa
Immediate neighbours	glnR, ynxB
Get the DNA and protein sequences (Barbe et al., 2009)
Genetic context This image was kindly provided by SubtiList

The gene

Basic information

• Locus tag: BSU17460

Phenotypes of a mutant

auxotrophic for glutamine

Database entries

• DBTBS entry: [1]

• SubtiList entry: [2]

The protein

Basic information/ Evolution

• Catalyzed reaction/ biological activity: ATP + L-glutamate + NH₃ = ADP + phosphate + L-glutamine (according to Swiss-Prot)

• Protein family: glutamine synthetase family (according to Swiss-Prot)

• Paralogous protein(s):

Extended information on the protein

• Kinetic information: K(M) for: Glu: 27 mM, ATP: 2.4 mM, ammonium: 0.18 mM; v(max): 3.7 µmol/min/mg

• Domains: glutamate binding flap (aa 300 ... 306: protects unstable intermediates from abberant hydrolysis)

• Modification: phosphorylated on ser/ thr/ tyr PubMed

• Cofactor(s): Mg(2+)

• Effectors of protein activity: feedback inhibition by glutamine, glutamine binds thhe entrance site for glutamate

• Interactions: TnrA-GlnA, GlnR-GlnA, (only the feedback-inhibited enzyme interacts with TnrA and GlnR)

• Localization: cytoplasm (according to Swiss-Prot)

Database entries

• Structure: 2GLS (enzyme from Salmonella typhimurium)

• UniProt: P12425

• KEGG entry: [3]

• E.C. number: 6.3.1.2

Additional information

GlnA is a homooligomer of 12 subunits

Expression and regulation

• Operon: glnR-glnA PubMed

• Sigma factor: SigA

• Regulation:
  • expressed in the absence of glutamine (GlnR) PubMed
  • repressed in the absence of good nitrogen sources (glutamine or ammonium) (TnrA) PubMed

• Regulatory mechanism:
  • GlnR-GlnA complex: transcription repression PubMed
  • TnrA: transcription repression PubMed

• Additional information:

Biological materials

• Mutant: GP247 (cat), available in Stülke lab

• Expression vector:
  • expression/ purification from E. coli, with N-terminal Strep-tag (in pGP172): pGP174, available in Stülke lab

• lacZ fusion:

• GFP fusion:

• two-hybrid system:

• Antibody: available in Karl Forchhammer lab

Labs working on this gene/protein

Susan Fisher, Boston, USA homepage