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: rocG
MW, pI	46.2 kDa, 6.28
Gene length, protein length	1272 bp, 424 amino acids
Immediate neighbours	rocA, sivA
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

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

• BsubCyc: BSU37790

• 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

• BsubCyc: BSU37790

• 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

• • number of protein molecules per cell (complex medium with amino acids, without glucose): 16024 PubMed

Biological materials

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

• Expression vector:
  • expression of native rocG in B. subtilis: pGP529 (in pBQ200), available in Jörg Stülke's lab PubMed
  • 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 Jörg Stülke's lab
  • for expression/ purification from E. coli with N-terminal His-tag and thrombin cleavage site, in pWH844: pGP860, available in Jörg Stülke's lab
  • purification from B. subtilis with an N-terminal Strep-tag, for SPINE, (in pGP380): pGP1709, available in Jörg Stülke's lab

• lacZ fusion:

• GFP fusion:

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

• Antibody: available in Jörg Stülke's 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

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)

Jason R Treberg, Margaret E Brosnan, Malcolm Watford, John T Brosnan
On the reversibility of glutamate dehydrogenase and the source of hyperammonemia in the hyperinsulinism/hyperammonemia syndrome.
Adv Enzyme Regul: 2010, 50(1);34-43
[PubMed:19895831] [WorldCat.org] [DOI] (I p)

Victoria I Bunik, Alisdair R Fernie
Metabolic control exerted by the 2-oxoglutarate dehydrogenase reaction: a cross-kingdom comparison of the crossroad between energy production and nitrogen assimilation.
Biochem J: 2009, 422(3);405-21
[PubMed:19698086] [WorldCat.org] [DOI] (I e)

N M Brunhuber, J S Blanchard
The biochemistry and enzymology of amino acid dehydrogenases.
Crit Rev Biochem Mol Biol: 1994, 29(6);415-67
[PubMed:7705101] [WorldCat.org] [DOI] (P p)

R C Hudson, R M Daniel
L-glutamate dehydrogenases: distribution, properties and mechanism.
Comp Biochem Physiol B: 1993, 106(4);767-92
[PubMed:8299344] [WorldCat.org] [DOI] (P p)

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)