Xpt

• Description: xanthine phosphoribosyltransferase
  
  

Gene name	xpt
Synonyms
Essential	no
Product	xanthine phosphoribosyltransferase
Function	purine salvage and interconversion
Gene expression levels in SubtiExpress: xpt
Metabolic function and regulation of this protein in SubtiPathways: xpt
MW, pI	20 kDa, 5.835
Gene length, protein length	582 bp, 194 aa
Immediate neighbours	pbuX, ypwA
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 nucleotides, membrane proteins

This gene is a member of the following regulons

G-box, PurR regulon

The gene

Basic information

• Locus tag: BSU22070

Database entries

• BsubCyc: BSU22070

• DBTBS entry: [1]

• SubtiList entry: [2]

The protein

Basic information/ Evolution

• Catalyzed reaction/ biological activity: XMP + diphosphate = 5-phospho-alpha-D-ribose 1-diphosphate + xanthine (according to Swiss-Prot)

• Protein family:

• Paralogous protein(s):

Extended information on the protein

• Kinetic information:

• Domains:

• Modification:

• Cofactor(s):

• Effectors of protein activity:

• Interactions:

• Localization:
  • cell membrane (according to Swiss-Prot)

Database entries

• BsubCyc: BSU22070

• Structure: 1Y0B, 2FXV (complex with GMP), 1Y27 (the riboswitch in complex with guanine)

• UniProt: P42085

• KEGG entry: [3]

• E.C. number: 2.4.2.22

Additional information

• subject to Clp-dependent proteolysis upon glucose starvation PubMed

Expression and regulation

• Operon: xpt-pbuX PubMed

• Expression browser: xpt PubMed

• Sigma factor: SigA PubMed

• Regulation:
  • repressed in the presence of adenine or adenosine (PurR) PubMed
  • induced in the absence of guanine (G-box) PubMed

• Regulatory mechanism:
  • G-box: transcription termination/ antitermination (riboswitch) PubMed
  • PurR: transcription repression (molecular inducer: PRPP) PubMed

• Additional information: subject to Clp-dependent proteolysis upon glucose starvation PubMed
  • number of protein molecules per cell (minimal medium with glucose and ammonium): 2789 PubMed
  • number of protein molecules per cell (complex medium with amino acids, without glucose): 5194 PubMed

Biological materials

• Mutant:

• Expression vector:

• lacZ fusion: pGP430 (in pAC7), available in Stülke lab

• GFP fusion:

• two-hybrid system:

• Antibody:

References

Otmar M Ottink, Ivo M Westerweele, Marco Tesssari, Frank H T Nelissen, Hans A Heus, Sybren S Wijmenga
1H and 13C resonance assignments of a guanine sensing riboswitch's terminator hairpin.
Biomol NMR Assign: 2010, 4(1);89-91
[PubMed:20204714] [WorldCat.org] [DOI] (I p)

Janina Buck, Jonas Noeske, Jens Wöhnert, Harald Schwalbe
Dissecting the influence of Mg2+ on 3D architecture and ligand-binding of the guanine-sensing riboswitch aptamer domain.
Nucleic Acids Res: 2010, 38(12);4143-53
[PubMed:20200045] [WorldCat.org] [DOI] (I p)

Susan Arent, Anders Kadziola, Sine Larsen, Jan Neuhard, Kaj Frank Jensen
The extraordinary specificity of xanthine phosphoribosyltransferase from Bacillus subtilis elucidated by reaction kinetics, ligand binding, and crystallography.
Biochemistry: 2006, 45(21);6615-27
[PubMed:16716072] [WorldCat.org] [DOI] (P p)

Per Nygaard, Hans H Saxild
The purine efflux pump PbuE in Bacillus subtilis modulates expression of the PurR and G-box (XptR) regulons by adjusting the purine base pool size.
J Bacteriol: 2005, 187(2);791-4
[PubMed:15629952] [WorldCat.org] [DOI] (P p)

Alexander Serganov, Yu-Ren Yuan, Olga Pikovskaya, Anna Polonskaia, Lucy Malinina, Anh Tuân Phan, Claudia Hobartner, Ronald Micura, Ronald R Breaker, Dinshaw J Patel
Structural basis for discriminative regulation of gene expression by adenine- and guanine-sensing mRNAs.
Chem Biol: 2004, 11(12);1729-41
[PubMed:15610857] [WorldCat.org] [DOI] (P p)

Lars Engholm Johansen, Per Nygaard, Catharina Lassen, Yvonne Agersø, Hans H Saxild
Definition of a second Bacillus subtilis pur regulon comprising the pur and xpt-pbuX operons plus pbuG, nupG (yxjA), and pbuE (ydhL).
J Bacteriol: 2003, 185(17);5200-9
[PubMed:12923093] [WorldCat.org] [DOI] (P p)

H H Saxild, K Brunstedt, K I Nielsen, H Jarmer, P Nygaard
Definition of the Bacillus subtilis PurR operator using genetic and bioinformatic tools and expansion of the PurR regulon with glyA, guaC, pbuG, xpt-pbuX, yqhZ-folD, and pbuO.
J Bacteriol: 2001, 183(21);6175-83
[PubMed:11591660] [WorldCat.org] [DOI] (P p)

L C Christiansen, S Schou, P Nygaard, H H Saxild
Xanthine metabolism in Bacillus subtilis: characterization of the xpt-pbuX operon and evidence for purine- and nitrogen-controlled expression of genes involved in xanthine salvage and catabolism.
J Bacteriol: 1997, 179(8);2540-50
[PubMed:9098051] [WorldCat.org] [DOI] (P p)