Molecular cloning and characterization of a salinity stress-induced gene encoding DEAD-box helicase from the halophyte Apocynum venetum

Abstract

The genes encoding DEAD-box helicases play a key role in various abiotic stresses, including temperature, light, oxygen, and salt stress. A salt-responsive gene, designated AvDH1, was isolated from the halophyte dogbane (Apocynum venetum) by using suppression subtractive hybridization and RACE (rapid amplification of cDNA ends) PCR. The deduced amino acid sequence has nine conserved helicase motifs of the DEAD-box protein family. The AvDH1 gene is present as a single copy in the dogbane genome. This gene is expressed in response to NaCl and not polyethlene glycol (PEG) nor abscisic acid, and its expression increases with time. The transcription of AvDH1 is also induced by low temperature (4 degrees C), but its accumulation first increases then decreases with time. The purified recombinant protein contains ATP-dependent DNA helicase activity, ATP-independent RNA helicase activity, and DNA- or RNA-dependent ATPase activity. The ATPase activity of AvDH1 is stimulated more by single-stranded DNA than by double-stranded DNA or RNA. These results suggested that AvDH1 belonging to the DEAD-box helicase family is induced by salinity, functions as a typical helicase to unwind DNA and RNA, and may play an important role in salinity tolerance.

Genome-wide analysis of helicase gene family from rice and Arabidopsis: a comparison with yeast and human

“…Till date, 13 RNA helicases have been shown to be linked with the metabolism of aberrant and silencing RNA and have been reported to affect cell fate, plant development, stress responses, gene silencing at the transcriptional and post-transcriptional levels, detection and decay of aberrant RNA, RNA maturation and protein quality control (reviewed in Linder and Owttrim 2009). The DExH box RNA helicases, Carpel factory/Dicer-like 1 (DCL1) (Park et al 2002) and the DEAD-box RNA helicase, LOS4, STRS1 and STRS2 (Kant et al 2007) and AvDH1 (Liu et al 2008) are shown to be involved in plant stress responses. The los4-1 mutant was more sensitive to cold stress (Gong et al 2002) while the los4-2 mutant shows more tolerance to freezing stress but is more sensitive to heat stress (Gong et al 2005).…”

Helicases in Improving Abiotic Stress Tolerance in Crop Plants

“…This gene was found to be upregulated in response to NaCl and not in drought and abscisic acid. The AvDH1 transcript was also induced by cold stress, but its accumulation was first increased then decreased with time [39].…”

Plant MCM proteins: role in DNA replication and beyond

“…N terminal regions contain Zinc finger motif, which represents the largest class of eukaryotic transcription factors. The Zinc finger motif is involved in DNA-protein (Liu et al 2008;Pavletich and Pabo 1991) or protein-protein interaction (Tubon et al 2004). The pea MCM protein PsMCM2 contains a putative nuclear localization sequence (NLS) K(K/R)X(K/R), which is required for entering into nuclear during G1/S-phase (Fig.…”