Publications

• Human pyridoxal phosphatase. Molecular cloning, functional expression, and tissue distribution.

  Jang Y.M., Kim D.W., Kang T.-C., Won M.H., Baek N.-I., Moon B.J., Choi S.Y., Kwon O.-S.

  Pyridoxal phosphatase catalyzes the dephosphorylation of pyridoxal 5'-phosphate (PLP) and pyridoxine 5'-phosphate. A human brain cDNA clone was identified to the PLP phosphatase on the basis of peptide sequences obtained previously. The cDNA predicts a 296-amino acid protein with a calculated Mr o ... >> More

  Pyridoxal phosphatase catalyzes the dephosphorylation of pyridoxal 5'-phosphate (PLP) and pyridoxine 5'-phosphate. A human brain cDNA clone was identified to the PLP phosphatase on the basis of peptide sequences obtained previously. The cDNA predicts a 296-amino acid protein with a calculated Mr of 31698. The open reading frame is encoded by two exons located on human chromosome 22q12.3, and the exon-intron junction contains the GT/AG consensus splice site. In addition, a full-length mouse PLP phosphatase cDNA of 1978 bp was also isolated. Mouse enzyme encodes a protein of 292 amino acids with Mr of 31512, and it is localized on chromosome 15.E1. Human and mouse PLP phosphatase share 93% identity in protein sequence. A BLAST search revealed the existence of putative proteins in organism ranging from bacteria to mammals. Catalytically active human PLP phosphatase was expressed in Escherichia coli, and characteristics of the recombinant enzyme were similar to those of erythrocyte enzyme. The recombinant enzyme displayed Km and kcat values for pyridoxal of 2.5 microM and 1.52 s(-1), respectively. Human PLP phosphatase mRNA is differentially expressed in a tissue-specific manner. A single mRNA transcript of 2.1 kb was detected in all human tissues examined and was highly abundant in the brain. Obtaining the molecular properties for the human PLP phosphatase may provide new direction for investigating metabolic pathway involving vitamin B6. << Less

  J. Biol. Chem. 278:50040-50046(2003) [PubMed] [EuropePMC]

  This publication is cited by 2 other entries.

• Identification of YigL as a PLP/PNP phosphatase in <i>Escherichia coli</i>.

  Matsuo H., Yamada N., Hemmi H., Ito T.

  In various organisms, the coenzyme form of vitamin B₆, pyridoxal phosphate (PLP), is synthesized from pyridoxine phosphate (PNP). Control of PNP levels is crucial for metabolic homeostasis because PNP has the potential to inhibit PLP-dependent enzymes and proteins. Although the only kno ... >> More

  In various organisms, the coenzyme form of vitamin B₆, pyridoxal phosphate (PLP), is synthesized from pyridoxine phosphate (PNP). Control of PNP levels is crucial for metabolic homeostasis because PNP has the potential to inhibit PLP-dependent enzymes and proteins. Although the only known pathway for PNP metabolism in <i>Escherichia coli</i> involves oxidation by PNP oxidase, we detected a strong PNP phosphatase activity in <i>E. coli</i> cell lysate. To identify the unknown PNP phosphatase(s), we performed a multicopy suppressor screening using the <i>E. coli serA pdxH</i> strain, which displays PNP-dependent conditional lethality. The results showed that overexpression of the <i>yigL</i> gene, encoding a putative sugar phosphatase, effectively alleviated the PNP toxicity. Biochemical analysis revealed that YigL has strong phosphatase activity against PNP. A <i>yigL</i> mutant exhibited decreased PNP phosphatase activity, elevated intracellular PNP concentrations, and increased PNP sensitivity, highlighting the important role of YigL in PNP homeostasis. YigL also shows reactivity with PLP. The phosphatase activity of PLP in <i>E. coli</i> cell lysate was significantly reduced by mutation of <i>yigL</i> and nearly abolished by additional mutation of <i>ybhA</i>, which encodes putative PLP phosphatase. These results underscore the important contribution of YigL, in combination with YbhA, as a primary enzyme in the dephosphorylation of both PNP and PLP in <i>E. coli</i>.IMPORTANCEPyridoxine phosphate (PNP) metabolism is critical for both vitamin B₆ homeostasis and cellular metabolism. In <i>Escherichia coli</i>, oxidation of PNP was the only known mechanism for controlling PNP levels. This study uncovered a novel phosphatase-mediated mechanism for PNP homeostasis. Multicopy suppressor screening, kinetic analysis of the enzyme, and knockout/overexpression studies identified YigL as a key PNP phosphatase that contributes to PNP homeostasis when facing elevated PNP concentrations in <i>E. coli</i>. This study also revealed a significant contribution of YigL, in combination with YbhA, to PLP metabolism, shedding light on the mechanisms of vitamin B₆ regulation in bacteria. << Less

  Appl Environ Microbiol 90:e0127024-e0127024(2024) [PubMed] [EuropePMC]

  This publication is cited by 1 other entry.