CitZ

• Description: citrate synthase
  
  

Gene name	citZ
Synonyms	citA2
Essential	no
Product	citrate synthase II
Function	TCA cycle
Gene expression levels in SubtiExpress: citZ
Interactions involving this protein in SubtInteract: CitZ
Metabolic function and regulation of this protein in SubtiPathways: Central C-metabolism
MW, pI	41 kDa, 5.451
Gene length, protein length	1116 bp, 372 aa
Immediate neighbours	icd, ytwI
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

carbon core metabolism, phosphoproteins

This gene is a member of the following regulons

CcpA regulon, CcpC regulon

The gene

Basic information

• Locus tag: BSU29140

Phenotypes of a mutant

glutamate auxotrophy and a defect in sporulation PubMed

Database entries

• DBTBS entry: [1]

• SubtiList entry: [2]

The protein

Basic information/ Evolution

• Catalyzed reaction/ biological activity: Acetyl-CoA + H₂O + oxaloacetate = citrate + CoA (according to Swiss-Prot)

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

• Paralogous protein(s): MmgD, CitA

Extended information on the protein

• Kinetic information: Michaelis-Menten (Random Sequential Reaction Mechanism) PubMed

• Domains:

• Modification: phosphorylation on Ser-284 PubMed

• Cofactor(s):

• Effectors of protein activity:
  • Inhibited by acetyl-CoA, 2-oxoglutarate and NADH PubMed FEBS Letters
  • Inhibited by citrate and CoA (competitively against acetyl-CoA and non-competitively against oxaloacetate) PubMed
  • Inhibited by ATP competitively in B. subtilis strain 168 and HS 1A17 PubMed PubMed
    • In B. subtilis strain HS 2A2, ATP inhibits a non-competitive fashion PubMed
  • Activated by AMP PubMed

• Interactions:
  • CitZ-Mdh-Icd (this is the core of the TCA cycle metabolon) PubMed

• Localization:

Database entries

• Structure:
  • 2C6X
  • A discussion of citrate synthase structure
• UniProt: P39120

• KEGG entry: [3]

• E.C. number: 2.3.3.1

Additional information

• extensive information on the structure and enzymatic properties of CitZ can be found at Proteopedia

Expression and regulation

• Operon:
  • citZ-icd-mdh PubMed

• Expression browser: citZ PubMed

• Sigma factor: SigA PubMed

• Regulation:
  • repression by glucose (6.7-fold) (CcpA) PubMed
  • repression by glucose + glutamate (CcpC) PubMed
  • reduced expression at excess citrate concentrations or iron depletion (CitB) PubMed

• Regulatory mechanism:
  • CcpA: transcription repression, CcpC: transcription repression PubMed
  • CcpC: transcription repression (molecular inducer: citrate) PubMed
  • CitB: mRNA destabilization upon citrate accumulation or iron limitation PubMed

• Additional information:
  • The mRNA has a long 5' leader region. This may indicate RNA-based regulation PubMed

Biological materials

• Mutant: GP678 (erm), available in Stülke lab
  • 1A999 ( citZ::spec), PubMed, available at BGSC

• Expression vector:
  • pGP1120 (N-terminal Strep-tag, for SPINE, purification from B. subtilis, in pGP380) (available in Stülke lab)
  • pGP1776 (for expression, purification in E. coli with N-terminal Strep-tag, in pGP172, available in Stülke lab)
  • pGP1761 (expression with N-terminal His-tag from E. coli, in pWH844), 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 Stülke lab

• Antibody: available in Linc Sonenshein lab

Labs working on this gene/protein

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

Jörg Stülke, University of Göttingen, Germany Homepage

References

Original publications

Additional publications: PubMed