RocG

• Description: trigger enzyme: catabolic glutamate dehydrogenase induced by arginine, ornithine or proline, subject to carbon catabolite repression
  
  

Gene name	rocG
Synonyms
Essential	no
Product	trigger enzyme: glutamate dehydrogenase (major)
Function	arginine utilization, controls the activity of GltC
Gene expression levels in SubtiExpress: rocG
Interactions involving this protein in SubtInteract: RocG
Metabolic function and regulation of this protein in SubtiPathways: Ammonium/ glutamate
MW, pI	46.2 kDa, 6.28
Gene length, protein length	1272 bp, 424 amino acids
Immediate neighbours	rocA, sivA
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

utilization of amino acids, glutamate metabolism, transcription factors and their control, trigger enzyme

This gene is a member of the following regulons

AbrB regulon, AhrC regulon, CcpA regulon, RocR regulon, SigL regulon

The gene

Basic information

• Locus tag: BSU37790

Phenotypes of a mutant

• Poor growth on complex media such as SP (sporulation medium). No growth in minimal media with arginine as the only carbon source. Rapid accumulation of suppressor mutants (gudB1)
• sensitive to ß-lactam antibiotics such as cefuroxime and to fosfomycin (suppressed by activation of gudB) due to the downregulation of the SigW regulon PubMed
• transcription profile of a rocG gudB mutant strain: GEO PubMed

Database entries

• DBTBS entry: [1]

• SubtiList entry: [2]

• GEO entry: [3] (rocG gudB mutant vs. wild type)

The protein

Basic information/ Evolution

• Catalyzed reaction/ biological activity: L-glutamate + H₂O + NAD⁺ = 2-oxoglutarate + NH₃ + NADH + H⁺ (according to Swiss-Prot), controls the activity of the GltC transcription activator PubMed

• Protein family: Glu/Leu/Phe/Val dehydrogenases family (according to Swiss-Prot)

• Paralogous protein(s): GudB

Extended information on the protein

• Kinetic information: K_M [glutamate] = 2.9 mM, K_M [ammonium] = 18 mM PubMed

• Domains:

• Modification:

• Cofactor(s): NAD⁺/NADH + H⁺

• Effectors of protein activity:

• Interactions:
  • RocG-GltC, this interaction prevents transcription activation of the gltA-gltB operon by GltC PubMed

• Localization:

Database entries

• Structure: 3K92 (super-repressor mutant that is capable of constitutive inactivation of GltC, E93K mutation) PubMed

• UniProt: P39633

• KEGG entry: [4]

• E.C. number: 1.4.1.2

Expression and regulation

• Operon: rocG PubMed

• Expression browser: rocG PubMed

• Sigma factor: SigL PubMed

• Regulation:
  • induced by arginine (RocR, AhrC), ornithine or proline PubMed
  • subject to carbon catabolite repression (CcpA) PubMed

• Regulatory mechanism:
  • RocR: transcription activation PubMed
  • AhrC: transcription activation PubMed
  • CcpA: transcription repression PubMed
  • AbrB: transcription repression PubMed

• Additional information:

Activation by RocR requires binding of RocR to a downstream element PubMed

Biological materials

• Mutant: GP747 (spc), GP726 (aphA3), GP810 (del tet), GP1157 (cat) all available in Stülke lab

• Expression vector:
  • expression of native rocG in B. subtilis: pGP529 (in pBQ200), available in Stülke lab
  • for purification of RocG from E. coli carrying an N-terminal Strep-tag: pGP902 (in pGP172), a series of rocG variants is also available in pGP172, available in Stülke lab
  • for expression/ purification from E. coli with N-terminal His-tag and thrombin cleavage site, in pWH844: pGP860, available in Stülke lab
  • purification from B. subtilis with an N-terminal Strep-tag, for SPINE, (in pGP380): pGP1709, available in Stülke lab

• lacZ fusion:

• GFP fusion:

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

• Antibody: available in Stülke lab

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

Structural analysis of glutamate dehydrogenase

Katrin Gunka, Joseph A Newman, Fabian M Commichau, Christina Herzberg, Cecilia Rodrigues, Lorraine Hewitt, Richard J Lewis, Jörg Stülke
Functional dissection of a trigger enzyme: mutations of the bacillus subtilis glutamate dehydrogenase RocG that affect differentially its catalytic activity and regulatory properties.
J Mol Biol: 2010, 400(4);815-27
[PubMed:20630473] [WorldCat.org] [DOI] (I p)

T J Stillman, P J Baker, K L Britton, D W Rice
Conformational flexibility in glutamate dehydrogenase. Role of water in substrate recognition and catalysis.
J Mol Biol: 1993, 234(4);1131-9
[PubMed:8263917] [WorldCat.org] [DOI] (P p)