Functional analysis of a calcium-binding transcription factor involved in plant salt stress signaling.
Calcium is known to serve as a secondary messenger to mediate salt stress signaling pathway. We found a calcium-binding basic/helix-loop-helix-type transcription factor (AtNIG1) as a salt stress-responsive gene by using the suppression subtractive hybridization. The AtNIG1 was targeted into nucleus and bound to (45)Ca(2+), suggesting that AtNIG1 is a nuclear calcium-binding protein. In addition, AtNIG1 bound specifically to the E-box-DNA sequence (CANNTG), which is found in the promoter regions of many salt stress-related genes. Functional analyses with an atnig1-1 knockout mutant revealed that the mutant plants show enhanced sensitivity to salt stress. Further analyses indicated that the atnig1-1 plants have reduced survival rate, fresh weight, chlorophyll content, and protein content upon salt stress, suggesting that the AtNIG1 plays a critical role in plant salt stress signaling. Therefore, this study represents that AtNIG1 is the first known calcium-binding transcription factor involved in plant salt stress signaling.
Kim
Jiyoung
J
Kiyong Biotechnology, 418-29 Goejong-Dong, Saha-Gu, Busan 604-083, South Korea.
Kim
Ho-Young
HY
D021581:Active Transport, Cell Nucleus / Q000187:drug effects / Q000235:genetics; D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D051792:Basic Helix-Loop-Helix Proteins / Q000235:genetics / Q000378:metabolism*; D002118:Calcium / Q000378:metabolism; D002135:Calcium-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D002467:Cell Nucleus / Q000235:genetics / Q000378:metabolism; D008969:Molecular Sequence Data; D030821:Plants, Genetically Modified / Q000235:genetics / Q000378:metabolism; D011485:Protein Binding / Q000187:drug effects / Q000235:genetics; D015398:Signal Transduction / Q000187:drug effects / Q000235:genetics; D012965:Sodium Chloride / Q000494:pharmacology*
D029681:Arabidopsis Proteins; D051792:Basic Helix-Loop-Helix Proteins; D002118:Calcium; D002135:Calcium-Binding Proteins; D012965:Sodium Chloride