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Updated: May 5, 2026
Lignin Down-regulation of Zea mays via dsRNAi and Klason Lignin Analysis
Published on: July 23, 2014
Identification of a type I Ca2+/Mg2+-dependent endonuclease induced in maize cells exposed to camptothecin
Núria Sánchez-Pons1, Carlos M Vicient
1Department of Molecular Genetics, Centre for Research in Agricultural Genomics CRAG (CSIC-IRTA-UAB-UB), Campus UAB, Bellaterra (Cerdanyola del Vallès), 08193 Barcelona, Spain. carlos.vicient@cragenomica.es.
Background:
Camptothecin is a plant alkaloid that specifically binds topoisomerase I, inhibiting its activity and inducing double stranded breaks in DNA and activating the cell responses to DNA damage.
Results:
Maize cultured cells were incubated in the presence of different concentrations of camptothecin. Camptothecin inhibits cultured cell growth, induces genomic DNA degradation, and induces a 32 kDa Ca2+/Mg2+-dependent nuclease activity. This nuclease, we called CaMNUC32, is inhibited by Zn2+ and by acid pH, it is mainly localized in the nucleus and it cleaves single- and double-stranded DNA, with a higher activity against single-stranded DNA. Two-dimensional electrophoresis combined with mass spectrometry suggests that CaMNUC32 is a member of the type I S1/P1 nuclease family. This type of nucleases are usually Zn2+-dependent but our results support previous indications that S1-type nucleases have a wide variety of enzyme activities, including Ca2+/Mg2+-dependent.
Conclusions:
We have identified and characterized CaMNUC32, a 32 kDa Ca2+/Mg2+-dependent nuclease of the S1/P1 family induced by the topoisomerase I inhibitor camptothecin in maize cultured cells.
