Cloning and expression analysis of SKn-type dehydrin gene from bean in response to heavy metals.
A heavy metal responsive gene PvSR3 (GenBank accession number U54703) encoding an acid dehydrin was isolated from a mercuric chloride-treated bean (Phaseolus vulgaris L.) leaf cDNA library by differential screening using cDNAs derived from treated and untreated plants. The PvSR3 cDNA is 981-bp long and has a 606-bp open-reading frame with a 202-residue-deduced amino acid sequence. The PvSR3 sequence contains two conserved repeats of the characteristic lysine-rich K segment (EKKGIMDKIKEKLPG) preceded by an 8-serine residue stretch, whereas the Y segment (DEYGNP) conserved motif is absent. The deduced protein has a calculated molecular weight of 23 kDa and an isoelectric point of 5.2. Sequence similarity and comparative analysis showed that PvSR3 shares 70 and 73% similarity with the dehydrin of poplar and pepper, respectively. Southern hybridizations indicated that PvSR3 was a low copy-number gene. Northern blot analysis revealed that PvSR3 mRNA was weakly detected in seedling leaves. However, the gene expression was strongly stimulated by heavy metals, such as mercury, cadmium, arsenic, and copper, whereas virus infection and salt had little effect on it. In contrast, PvSR3 was not responsive to drought or abscisic acid (ABA), and was downregulated by UV radiation. Furthermore, PvSR3 was upregulated by the exogenous signaling molecules, including salicylic acid (SA) and hydrogen peroxide (H2O2). It is suggested that PvSR3 is extremely related to heavy metal stress, and might play an important role in metal detoxification and resistance to the damage caused by heavy metals.
Zhang
Yuxiu
Y
Department of Biological Engineering, School of Chemical and Environmental Engineering, China University of Mining and Technology (Beijing), Xueyuan Road 11, Beijing 100083, China.
Li
Jinmei
J
Yu
Fei
F
Cong
Lin
L
Wang
Liyan
L
Burkard
Gérard
G
Chai
Tuanyao
T
D000040:Abscisic Acid / Q000494:pharmacology; D000595:Amino Acid Sequence; D001483:Base Sequence; D015152:Blotting, Northern; D015139:Blotting, Southern; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification; D020869:Gene Expression Profiling; D018506:Gene Expression Regulation, Plant / Q000187:drug effects / Q000528:radiation effects; D015723:Gene Library; D006861:Hydrogen Peroxide / Q000494:pharmacology; D019216:Metals, Heavy / Q000494:pharmacology*; D008969:Molecular Sequence Data; D027805:Phaseolus / Q000187:drug effects* / Q000235:genetics / Q000528:radiation effects; D010940:Plant Proteins / Q000235:genetics*; D020156:Salicylic Acid / Q000494:pharmacology; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid; D012965:Sodium Chloride / Q000494:pharmacology; D013997:Time Factors
D018076:DNA, Complementary; D019216:Metals, Heavy; D010940:Plant Proteins; C070556:dehydrin proteins, plant; D012965:Sodium Chloride; D000040:Abscisic Acid; D006861:Hydrogen Peroxide; D020156:Salicylic Acid