In enzymology, a phosphopantothenate—cysteine ligase also known as phosphopantothenoylcysteine synthetase (PPCS) is an enzyme (EC 6.3.2.5) that catalyzes the chemical reaction which constitutes the second of five steps involved in the conversion of pantothenate to Coenzyme A. The reaction is:

NTP + (R)-4'-phosphopantothenate + L-cysteine ${\displaystyle \rightleftharpoons }$ NMP + diphosphate + N-[(R)-4'-phosphopantothenoyl]-L-cysteine

The nucleoside triphosphate (NTP) involved in the reaction varies from species to species. Phosphopantothenate—cysteine ligase from the bacterium Escherichia coli uses cytidine triphosphate (CTP) as an energy donor, whilst the human isoform uses adenosine triphosphate (ATP).^[1]

Nomenclature

This enzyme belongs to the family of ligases, specifically those forming carbon-nitrogen bonds as acid-D-amino-acid ligases (peptide syntheses). The systematic name of this enzyme class is (R)-4'-phosphopantothenate:L-cysteine ligase. This enzyme is also called phosphopantothenoylcysteine synthetase.

Gene

PPCS
Available structures PDB Ortholog search: PDBe RCSB List of PDB id codes 1P9O
Identifiers
Aliases	PPCS, Phosphopantothenate—cysteine ligase, phosphopantothenoylcysteine synthetase, CMD2C
External IDs	OMIM: 609853 MGI: 1915237 HomoloGene: 6173 GeneCards: PPCS
Gene location (Human) Chr. Chromosome 1 (human)[2] Band 1p34.2 Start 42,456,117 bp[2] End 42,473,385 bp[2]
Gene location (Mouse) Chr. Chromosome 4 (mouse)[3] Band 4|4 D2.1 Start 119,275,727 bp[3] End 119,279,617 bp[3]
RNA expression pattern Bgee Human Mouse (ortholog) Top expressed in body of pancreas Achilles tendon rectum monocyte left adrenal gland body of stomach gallbladder minor salivary gland right coronary artery skin of abdomen Top expressed in proximal tubule yolk sac adrenal gland left lobe of liver kidney duodenum jejunum facial motor nucleus brown adipose tissue ileum More reference expression data BioGPS n/a
Gene ontology Molecular function phosphopantothenate--cysteine ligase activity ligase activity Cellular component cytosol Biological process coenzyme A biosynthetic process Sources:Amigo / QuickGO
Orthologs Species Human Mouse Entrez 79717 106564 Ensembl ENSG00000127125 ENSMUSG00000028636 UniProt Q9HAB8 Q8VDG5 RefSeq (mRNA) NM_001077447 NM_001287506 NM_001287507 NM_001287508 NM_001287509 NM_001287510 NM_001287511 NM_024664 NM_026494 NM_001355214 RefSeq (protein) NP_001070915 NP_001274435 NP_001274436 NP_001274437 NP_001274438 NP_001274439 NP_001274440 NP_078940 NP_080770 NP_001342143 Location (UCSC) Chr 1: 42.46 – 42.47 Mb Chr 4: 119.28 – 119.28 Mb PubMed search [4] [5]
Wikidata
View/Edit Human View/Edit Mouse

Phosphopantothenoylcysteine synthetase in humans is encoded by the PPCS gene.^[6]

Protein structure

As of late 2007, 5 structures have been solved for this class of enzymes, with PDB accession codes 1P9O, 1U7U, 1U7W, 1U7Z, and 1U80.

References

Further reading

External links

• PDBe-KB provides an overview of all the structure information available in the PDB for Human Phosphopantothenate—cysteine ligase