The Ser/Thr/Tyr phosphoproteome of Lactococcus lactis IL1403 reveals multiply phosphorylated proteins

Proteomics. 2008 Sep;8(17):3486-93. doi: 10.1002/pmic.200800069.


Recent phosphoproteomics studies of several bacterial species have firmly established protein phosphorylation on Ser/Thr/Tyr residues as a PTM in bacteria. In particular, our recent reports on the Ser/Thr/Tyr phosphoproteomes of bacterial model organisms Bacillus subtilis and Escherichia coli detected over 100 phosphorylation events in each of the bacterial species. Here we extend our analyses to Lactococcus lactis, a lactic acid bacterium widely employed by the food industry, in which protein phosphorylation at Ser/Thr/Tyr residues was barely studied at all. Despite the lack of almost any prior evidence of Ser/Thr/Tyr protein phosphorylation in L. lactis, we identified a phosphoproteome of a size comparable to that of E. coli and B. subtilis, with 73 phosphorylation sites distributed over 63 different proteins. The presence of several multiply phosphorylated proteins, as well as over-representation of phosphothreonines seems to be the distinguishing features of the L. lactis phosphoproteome. Evolutionary comparison and the conservation of phosphorylation sites in different bacterial organisms indicate that a majority of the detected phosphorylation sites are species-specific, and therefore have probably co-evolved with the adaptation of the bacterial species to their present-day ecological niches.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Bacterial Proteins / analysis*
  • Glycolysis
  • Lactococcus lactis / metabolism*
  • Phosphopeptides / metabolism*
  • Phosphorylation
  • Proteome / analysis*
  • Serine / metabolism
  • Tandem Mass Spectrometry
  • Threonine / metabolism
  • Tyrosine / metabolism


  • Bacterial Proteins
  • Phosphopeptides
  • Proteome
  • Threonine
  • Tyrosine
  • Serine