A novel target of IscS in Escherichia coli: participating in DNA phosphorothioation

PLoS One. 2012;7(12):e51265. doi: 10.1371/journal.pone.0051265. Epub 2012 Dec 11.

Abstract

Many bacterial species modify their DNA with the addition of sulfur to phosphate groups, a modification known as DNA phosphorothioation. DndA is known to act as a cysteine desulfurase, catalyzing a key biochemical step in phosphorothioation. However, bioinformatic analysis revealed that 19 out of the 31 known dnd gene clusters, contain only four genes (dndB-E), lacking a key cysteine desulfurase corresponding gene. There are multiple cysteine desulfurase genes in Escherichia coli, but which one of them participates into DNA phosphorothioation is unknown. Here, by employing heterologous expression of the Salmonella enterica dnd gene cluster named dptBCDE in three E. coli mutants, each of which lacked a different cysteine desulfurase gene, we show that IscS is the only cysteine desulfurase that collaborates with dptB-E, resulting in DNA phosphorothioation. Using a bacterial two-hybrid system, protein interactions between IscS and DptC, and IscS and DptE were identified. Our findings revealed IscS as a key participant in DNA phosphorothioation and lay the basis for in-depth analysis of the DNA phosphorothioation biochemical pathway.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Carbon-Sulfur Lyases* / genetics
  • Carbon-Sulfur Lyases* / metabolism
  • DNA / chemistry
  • DNA / metabolism*
  • Escherichia coli* / genetics
  • Escherichia coli* / metabolism
  • Gene Expression Regulation, Bacterial
  • Multigene Family
  • Salmonella enterica / genetics
  • Salmonella enterica / metabolism
  • Sulfur / chemistry
  • Sulfur / metabolism

Substances

  • Sulfur
  • DNA
  • Carbon-Sulfur Lyases
  • cysteine desulfurase

Grants and funding

The authors wish to thank the National Science Foundation of China, the Ministry of Science and Technology (973 and 863 programs), the Ministry of Education of China, the Shanghai Municipal Council of Science and Technology and Shanghai Leading Academic Discipline Project B203, the State Key Laboratory of Bio-Organic and Natural Products Chemistry (CAS) and the National Program of Development of Transgenic New Species of China for research support. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.