Studies on cyanobacterial protein PipY shed light on structure, potential functions, and vitamin B6 -dependent epilepsy

FEBS Lett. 2017 Oct;591(20):3431-3442. doi: 10.1002/1873-3468.12841. Epub 2017 Sep 20.

Abstract

The Synechococcus elongatus COG0325 gene pipY functionally interacts with the nitrogen regulatory gene pipX. As a first step toward a molecular understanding of such interactions, we characterized PipY. This 221-residue protein is monomeric and hosts pyridoxal phosphate (PLP), binding it with limited affinity and losing it upon incubation with D-cycloserine. PipY crystal structures with and without PLP reveal a single-domain monomer folded as the TIM barrel of type-III fold PLP enzymes, with PLP highly exposed, fitting a role for PipY in PLP homeostasis. The mobile PLP phosphate-anchoring C-terminal helix might act as a trigger for PLP exchange. Exploiting the universality of COG0325 functions, we used PipY in site-directed mutagenesis studies to shed light on disease causation by epilepsy-associated mutations in the human COG0325 gene PROSC.

Keywords: COG0325; Synechococcus elongatus PCC7942; pyridoxal phosphate proteins.

Publication types

  • Letter

MeSH terms

  • Amino Acid Motifs
  • Bacterial Proteins / chemistry*
  • Bacterial Proteins / genetics
  • Bacterial Proteins / metabolism
  • Binding Sites
  • Cloning, Molecular
  • Crystallography, X-Ray
  • Cycloserine / chemistry
  • Cycloserine / metabolism
  • Epilepsy / metabolism
  • Epilepsy / pathology
  • Escherichia coli / genetics
  • Escherichia coli / metabolism
  • Gene Expression
  • Humans
  • Kinetics
  • Models, Molecular
  • Mutagenesis, Site-Directed
  • PII Nitrogen Regulatory Proteins / chemistry*
  • PII Nitrogen Regulatory Proteins / genetics
  • PII Nitrogen Regulatory Proteins / metabolism
  • Protein Binding
  • Protein Conformation, alpha-Helical
  • Protein Conformation, beta-Strand
  • Protein Folding
  • Protein Interaction Domains and Motifs
  • Proteins / chemistry*
  • Proteins / genetics
  • Proteins / metabolism
  • Pyridoxal Phosphate / chemistry*
  • Pyridoxal Phosphate / metabolism
  • Recombinant Proteins / chemistry
  • Recombinant Proteins / genetics
  • Recombinant Proteins / metabolism
  • Substrate Specificity
  • Synechococcus / chemistry*
  • Synechococcus / metabolism
  • Thermodynamics

Substances

  • Bacterial Proteins
  • PII Nitrogen Regulatory Proteins
  • PLPBP protein, human
  • Proteins
  • Recombinant Proteins
  • Pyridoxal Phosphate
  • Cycloserine