Pyridoxal 5'-phosphate (PLP), the catalytically active form of vitamin B6, plays a pivotal role in metabolism as an enzyme cofactor. PLP is a very reactive molecule and it can be very toxic unless its intracellular concentration is finely regulated. In Escherichia coli, PLP formation is catalyzed by pyridoxine 5'-phosphate oxidase (PNPO), a homodimeric FMN-dependent enzyme that is responsible for the last step of PLP biosynthesis and is also involved in the PLP salvage pathway. We have recently observed that E. coli PNPO undergoes an allosteric feedback inhibition by PLP, caused by a strong allosteric coupling between PLP binding at the allosteric site and substrate binding at the active site. Here we report the crystallographic identification of the PLP allosteric site, located at the interface between the enzyme subunits and mainly circumscribed by three arginine residues (Arg23, Arg24 and Arg215) that form an "arginine-cage" and efficiently trap PLP. The crystal structure of the PNPO-PLP complex, characterized by a marked structural asymmetry, presents only one PLP molecule bound at the allosteric site of one monomer, and sheds light on the allosteric inhibition mechanism that makes the enzyme-substrate-PLP ternary complex catalytically incompetent. Site directed mutagenesis studies focused on the "arginine cage" validate the identity of the allosteric site and provide an effective means to modulate the allosteric properties of the enzyme, from the loosening of the allosteric coupling (in the R23L/R24L and R23L/R215L variants) to the complete loss of allosteric properties (in the R23L/R24L/R215L variant).

Identification and characterization of the pyridoxal 5'-phosphate allosteric site in Escherichia coli pyridoxine 5'-phosphate oxidase / Barile, Anna; Battista, Theo; Fiorillo, Annarita; Luigi di Salvo, Martino; Malatesta, Francesco; Tramonti, Angela; Ilari, Andrea; Contestabile, Roberto. - In: THE JOURNAL OF BIOLOGICAL CHEMISTRY. - ISSN 0021-9258. - 296:(2021), pp. 1-16. [10.1016/j.jbc.2021.100795]

Identification and characterization of the pyridoxal 5'-phosphate allosteric site in Escherichia coli pyridoxine 5'-phosphate oxidase

Barile, Anna;Battista, Theo;Fiorillo, Annarita;Luigi di Salvo, Martino;Malatesta, Francesco;Tramonti, Angela;Ilari, Andrea;Contestabile, Roberto
2021

Abstract

Pyridoxal 5'-phosphate (PLP), the catalytically active form of vitamin B6, plays a pivotal role in metabolism as an enzyme cofactor. PLP is a very reactive molecule and it can be very toxic unless its intracellular concentration is finely regulated. In Escherichia coli, PLP formation is catalyzed by pyridoxine 5'-phosphate oxidase (PNPO), a homodimeric FMN-dependent enzyme that is responsible for the last step of PLP biosynthesis and is also involved in the PLP salvage pathway. We have recently observed that E. coli PNPO undergoes an allosteric feedback inhibition by PLP, caused by a strong allosteric coupling between PLP binding at the allosteric site and substrate binding at the active site. Here we report the crystallographic identification of the PLP allosteric site, located at the interface between the enzyme subunits and mainly circumscribed by three arginine residues (Arg23, Arg24 and Arg215) that form an "arginine-cage" and efficiently trap PLP. The crystal structure of the PNPO-PLP complex, characterized by a marked structural asymmetry, presents only one PLP molecule bound at the allosteric site of one monomer, and sheds light on the allosteric inhibition mechanism that makes the enzyme-substrate-PLP ternary complex catalytically incompetent. Site directed mutagenesis studies focused on the "arginine cage" validate the identity of the allosteric site and provide an effective means to modulate the allosteric properties of the enzyme, from the loosening of the allosteric coupling (in the R23L/R24L and R23L/R215L variants) to the complete loss of allosteric properties (in the R23L/R24L/R215L variant).
2021
allosteric regulation; asymmetry; bacterial metabolism; crystal structure; enzyme inhibitor; pyridoxal phosphate; pyridoxine 5’-phosphate oxidase; vitamin B(6) metabolism
01 Pubblicazione su rivista::01a Articolo in rivista
Identification and characterization of the pyridoxal 5'-phosphate allosteric site in Escherichia coli pyridoxine 5'-phosphate oxidase / Barile, Anna; Battista, Theo; Fiorillo, Annarita; Luigi di Salvo, Martino; Malatesta, Francesco; Tramonti, Angela; Ilari, Andrea; Contestabile, Roberto. - In: THE JOURNAL OF BIOLOGICAL CHEMISTRY. - ISSN 0021-9258. - 296:(2021), pp. 1-16. [10.1016/j.jbc.2021.100795]
File allegati a questo prodotto
File Dimensione Formato  
Barile_Identification_2021.pdf

accesso aperto

Tipologia: Versione editoriale (versione pubblicata con il layout dell'editore)
Licenza: Creative commons
Dimensione 3.64 MB
Formato Adobe PDF
3.64 MB Adobe PDF

I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.

Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11573/1554277
Citazioni
  • ???jsp.display-item.citation.pmc??? 4
  • Scopus 10
  • ???jsp.display-item.citation.isi??? 9
social impact