Abstract
Deoxyhypusine synthase (DHS) is encoded by a nuclear gene and is the key enzyme involved in the post-translational activation of the eukaryotic translation initiation factor eIF5A. DHS plays important roles in plant growth and development. To gain a better understanding of DHS, the petunia (Petunia hybrida) PhDHS gene was isolated, and the role of PhDHS in plant growth was analyzed. PhDHS protein was localized to the nucleus and cytoplasm. Virus-mediated PhDHS silencing caused a sectored chlorotic leaf phenotype. Chlorophyll levels and photosystem II activity were reduced, and chloroplast development was abnormal in PhDHS-silenced leaves. In addition, PhDHS silencing resulted in extended leaf longevity and thick leaves. A proteome assay revealed that 308 proteins are upregulated and 266 proteins are downregulated in PhDHS-silenced plants compared with control, among the latter, 21 proteins of photosystem I and photosystem II and 12 thylakoid (thylakoid lumen and thylakoid membrane) proteins. In addition, the mRNA level of PheIF5A-1 significantly decreased in PhDHS-silenced plants, while that of another three PheIF5As were not significantly affected in PhDHS-silenced plants. Thus, silencing of PhDHS affects photosynthesis presumably as an indirect effect due to reduced expression of PheIF5A-1 in petunia.Significance: PhDHS-silenced plants develop yellow leaves and exhibit a reduced level of photosynthetic pigment in mesophyll cells. In addition, arrested development of chloroplasts is observed in the yellow leaves.
Highlights
Deoxyhypusine synthase (DHS) is an enzyme thought to be present in all eukaryotic cells (Jenkins et al, 2001)
Recent research shows that alterations in the biosynthesis of hypusine promoted by the DHS silencing in A. thaliana, result in a wide variety of phenotypes affecting many biological processes related with development such as control of flowering time, the shoot and root architecture and root hair phenotypes
Full-length DHS cDNA was isolated from petunia ‘Ultra’ and was designated as PhDHS, which was predicted to encode a 375-amino acid protein
Summary
Deoxyhypusine synthase (DHS) is an enzyme thought to be present in all eukaryotic cells (Jenkins et al, 2001). In canola (Brassica napus), transgenic plants with DHS suppression exhibited delayed natural leaf senescence, increased leaf size, and subsequent increases in seed yield and tolerance to chronic sublethal stress (Wang et al, 2005a). These studies provided evidence for senescence-induced DHS in tomato and A. thaliana tissues that may facilitate the translation of mRNA species required for programmed cell death (Wang et al, 2001, 2003, 2005a). Recombinant tomato and tobacco DHS are capable of catalyzing the formation of a deoxyhypusine residue in A. thaliana and tobacco eIF-5A substrates, respectively (Ober and Hartmann, 1999; Wang et al, 2001)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
