IscS might participate DNA phosphorothioation directly.

Ethidium bromide-stained agarose gels. TAE (top gel), samples run in normal TAE buffer; PAA (bottom gel), samples run in TAE containing PAA. Expression of S. enterica dptB-E resulted in DNA S-modification and a fluorescent smear in all samples, except for E. coli ΔiscS. IscS was therefore the only gene that was required for DNA S-modification among the tested deletions.