Reversible inactivation of the CG specific SssI DNA (Cytosine-C5)- methyltransferase with a photocleavable protecting group

Philipp Rathert, Tamás Raskó, Markus Roth, Krystyna Ślaska-Kiss, Alfred Pingoud, Antal Kiss, Albert Jeltsch

Research output: Article

23 Citations (Scopus)


Caging of proteins by conjugation with a photocleavable group is a powerful approach for reversibly blocking enzymatic activity. Here we describe the covalent modification of the bacterial SssI DNA methyltransferase (M.SssI) with the cysteine-specific reagent 4,5-dimethoxy-2-nitrobenzylbromide (DMNBB). M.SssI contains two cysteine residues; replacement of the active-site Cys141 with Ser resulted in an approximately 100-fold loss of enzymatic activity; this indicates an important role for this residue in catalysis. However, replacement of Cys368 with Ala did not affect methyltransferase activity. Treatment of the Cys368Ala mutant enzyme with DMNBB led to an almost complete loss of activity. Irradiation of the inactivated enzyme with near-ultraviolet light (320-400 nm) restored 60% of the catalytic activity. This indicates that caging by DMNBB can be used for the reversible inactivation of M.SSSI. (Figure Presented)

Original languageEnglish
Pages (from-to)202-207
Number of pages6
Issue number2
Publication statusPublished - febr. 1 2007


ASJC Scopus subject areas

  • Biochemistry
  • Molecular Medicine
  • Molecular Biology
  • Organic Chemistry

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