Enzymes of cysteine synthesis show extensive and conserved modifications patterns that include N(α)-terminal acetylation

Amino Acids. 2010 Oct;39(4):1077-86. doi: 10.1007/s00726-010-0694-0. Epub 2010 Jul 24.

Abstract

Biosynthesis of cysteine is a two-step process in higher plants subsequently catalyzed by serine acetyltransferase (SAT) and O-acetylserine (thiol) lyase (OAS-TL) which are present in cytosol, plastids and mitochondria. Recently, the distribution of SAT and OAS-TL in these subcellular compartments was shown to be crucial for efficient cysteine synthesis in Arabidopsis thaliana. In this study, the abundances of OAS-TLs were quantified independently by immunological detection in crude protein extracts and by SAT affinity purification (SAP) of OAS-TL. OAS-TL A and B were evidenced to be the most abundant isoforms in all analyzed tissues, which is consistent with micro array-based transcript analyses. Application of SAP to Arabidopsis revealed significant modification of the major OAS-TL isoforms present in cytosol, plastids and mitochondria into up to seven subspecies. Specific OAS-TL isoforms were found to be differentially modified in the leaves, roots, stem and cell culture. Sulphur deficiency did not alter modification of OAS-TL proteins purified from cell culture that showed the highest complexity of OAS-TL modifications. However, the pattern of OAS-TL modification was found to be stable within an analyzed tissue, pointing not only to a high reproducibility of SAP but likely biological significance of each subspecies. The most abundant OAS-TL subspecies in cytosol and plastids were subject of N-terminal processing followed by acetylation of the newly originated N-terminus. The mode of N(α)-terminal acetylation of OAS-TL and its possible biological function are discussed.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Acetylation
  • Arabidopsis / enzymology*
  • Arabidopsis / genetics
  • Arabidopsis / metabolism
  • Arabidopsis Proteins / genetics
  • Arabidopsis Proteins / metabolism
  • Cysteine / biosynthesis*
  • Cysteine Synthase / chemistry
  • Cysteine Synthase / genetics
  • Cysteine Synthase / isolation & purification
  • Cysteine Synthase / metabolism*
  • Cytosol / enzymology
  • Electrophoresis, Polyacrylamide Gel
  • Gene Expression Regulation, Plant
  • Isoenzymes / chemistry
  • Isoenzymes / genetics
  • Isoenzymes / isolation & purification
  • Isoenzymes / metabolism*
  • Mass Spectrometry
  • Mitochondria / enzymology
  • Plant Leaves / enzymology
  • Plant Leaves / genetics
  • Plant Leaves / metabolism
  • Plant Roots / enzymology
  • Plant Stems / enzymology
  • Plastids / enzymology
  • Protein Processing, Post-Translational
  • Sequence Analysis, Protein
  • Serine O-Acetyltransferase / metabolism*
  • Sulfhydryl Compounds / metabolism
  • Sulfur / metabolism

Substances

  • Arabidopsis Proteins
  • Isoenzymes
  • Sulfhydryl Compounds
  • Sulfur
  • Serine O-Acetyltransferase
  • Cysteine Synthase
  • Cysteine