Molecular Cloning and Characterization of a Short-Chain Dehydrogenase Showing Activity with Volatile Compounds Isolated from Camellia sinensis
Camellia sinensis synthesizes and emits a large variety of volatile phenylpropanoids and benzenoids (VPB). To investigate the enzymes involved in the formation of these VPB compounds, a new C. sinensis short-chain dehydrogenase/reductase (CsSDR) was isolated, cloned, sequenced, and functionally characterized. The complete open reading frame of CsSDR contains 996 nucleotides with a calculated protein molecular mass of 34.5 kDa. The CsSDR recombinant protein produced in Escherichia coli exhibited dehydrogenase-reductase activity towards several major VPB compounds in C. sinensis flowers with a strong preference for NADP/NADPH co-factors, and showed affinity for (R)/(S)-1-phenylethanol (1PE), phenylacetaldehyde, benzaldehyde, and benzyl alcohol, and no affinity for acetophenone (AP) and 2-phenylethanol. CsSDR showed the highest catalytic efficiency towards (R)/(S)-1PE. Furthermore, the transient expression analysis in Nicotiana benthamiana plants validated that CsSDR could convert 1PE to AP in plants. CsSDR transcript level was not significantly affected by floral development and some jasmonic acid-related environmental stress, and CsSDR transcript accumulation was detected in most floral tissues such as receptacle and anther, which were main storage locations of VPB compounds. Our results indicate that CsSDR is expressed in C. sinensis flowers and is likely to contribute to a number of floral VPB compounds including the 1PE derivative AP.
KeywordsCamellia sinensis 1-Phenylethanol Phenylpropanoids Short chain dehydrogenase Volatile compound
C. sinensis short chain dehydrogenase/reductase
Open reading frame
Volatile phenylpropanoids and benzenoids
This work was supported by the “100 Talents Programme of the Chinese Academy of Sciences” (Y321011001 and 201209), the National Natural Science Foundation for Young Scholar of China (30900997), and the Foundation of Key Laboratory of Plant Resources Conservation and Sustainable Utilization, South China Botanical Garden, Chinese Academy of Sciences.
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