A cold-regulated nucleic acid-binding protein of winter wheat shares a domain with bacterial cold shock proteins.
The molecular mechanisms of cold acclimation are still largely unknown; however, it has been established that overwintering plants such as winter wheat increases freeze tolerance during cold treatments. In prokaryotes, cold shock proteins are induced by temperature downshifts and have been proposed to function as RNA chaperones. A wheat cDNA encoding a putative nucleic acid-binding protein, WCSP1, was isolated and found to be homologous to the predominant CspA of Escherichia coli. The putative WCSP1 protein contains a three-domain structure consisting of an N-terminal cold shock domain with two internal conserved consensus RNA binding domains and an internal glycine-rich region, which is interspersed with three C-terminal CX(2)CX(4)HX(4)C (CCHC) zinc fingers. Each domain has been described independently within several nucleotide-binding proteins. Northern and Western blot analyses showed that WCSP1 mRNA and protein levels steadily increased during cold acclimation, respectively. WCSP1 induction was cold-specific because neither abscisic acid treatment, drought, salinity, nor heat stress induced WCSP1 expression. Nucleotide binding assays determined that WCSP1 binds ssDNA, dsDNA, and RNA homopolymers. The capacity to bind dsDNA was nearly eliminated in a mutant protein lacking C-terminal zinc fingers. Structural and expression similarities to E. coli CspA suggest that WCSP1 may be involved in gene regulation during cold acclimation.
Karlson
Dale
D
Winter Stress Laboratory, National Agricultural Research Center for Hokkaido Region, Hitsujigaoka 1, Toyohira-ku, Sapporo 062-8555, Japan.
Nakaminami
Kentaro
K
Toyomasu
Tomonobu
T
Imai
Ryozo
R
D000595:Amino Acid Sequence; D000818:Animals; D001426:Bacterial Proteins / Q000737:chemistry / Q000378:metabolism*; D001483:Base Sequence; D003080:Cold Temperature; D018076:DNA, Complementary; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D008969:Molecular Sequence Data; D010940:Plant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D016601:RNA-Binding Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D012689:Sequence Homology, Nucleic Acid; D014908:Triticum / Q000378:metabolism*
D001426:Bacterial Proteins; D018076:DNA, Complementary; D004268:DNA-Binding Proteins; D010940:Plant Proteins; D012333:RNA, Messenger; D016601:RNA-Binding Proteins