Molecular cloning and characterization of a stress-induced peroxiredoxin Q gene in halophyte Suaeda salsa

Peroxiredoxin Q, as a member of peroxiredoxin gene family, was most recently cloned from plants. However, its molecular characteristics remain unclear. In this paper, we cloned a peroxiredoxin Q gene from a 400 mM NaCl-treated cDNA library of Suaeda salsa . The SsPrx Q gene (1 003 bp) contains an open reading frame of 214 amino acids with a molecular mass of 23.6 kDa. SsPrx Q showed high homology to the Prx Q of Sedum lineare , with 76% identities in deduced amino acid sequence. Southern blot analysis indicated that SsPrx Q gene has a single copy in S. salsa genome. Northern blot analysis showed that SsPrx Q gene expression was up-regulated by NaCl, mannitol, low temperature, H 2 O 2 , methyl viologen, and ABA. Studies of the recombinant protein produced in E. coli cells exhibited that it actually had a thioredoxin-dependent peroxidase activity, the characteristic of the Prx family. These results indicated that SsPrx Q may play an important role in protecting S. salsa from environmental stresses.