Journal of Life Science (생명과학회지)

Korean Society of Life Science (한국생명과학회)
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Molecular Cloning and Expression of the Metallothionein Gene under Environmental Stresses in Sweet Potato

고구마 metallothionein 유전자의 클로닝 및 환경 스트레스 하에서 발현 분석

  • Kim, Young-Hwa (Ubiquitous Healthcare Research Center, College of Liberal Arts, Inje University) ;
  • Yu, Eun Jeong (Institute of Digital Anti-Aging Healthcare, Graduate School of Inje University) ;
  • Huh, Gyung-Hye (Ubiquitous Healthcare Research Center, College of Liberal Arts, Inje University)
  • 김영화 (인제대학교 U-항노화헬스케어연구소 교양학부) ;
  • 유은정 (인제대학교 디지털항노화헬스케어학과) ;
  • 허경혜 (인제대학교 U-항노화헬스케어연구소 교양학부)
  • Received : 2017.10.13
  • Accepted : 2017.11.27
  • Published : 2017.12.30
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Abstract

The metallothionein (MT) gene (IbMT3) was selected from an EST library of suspension-cultured sweet potato cells. The MT gene, which is one of abundant ESTs in the library, is involved in stress regulation of cells and tissues. A full-length IbMT3 cDNA was obtained and analysis of its nucleotide sequence revealed that IbMT3 encoded a type 3 MT protein, based on its structural characteristics. The function of type 3 MT in plants is not yet known. Northern blot analysis showed stronger expression of IbMT3 in suspension-cultured cells than in sweet potato plant leaves. Since cell culture is known to impose a state of oxidative stress on cells, sweet potato plants were subjected to oxidative stress to investigate the transcriptional regulation of IbMT3. When the herbicide methyl viologen (MV) was administered for 6, 12, and 24 hr, IbMT3 transcription rapidly increased at 6 hr and then decreased. A cold treatment at $15^{\circ}C$ for 24 and 48 hr resulted in a gradual increase in IbMT3 expression. These findings indicate that IbMT3 expression is regulated in response to environmental and oxidative stress. IbMT3 isoform is expected to have antioxidant effects in sweet potato plants and may play an important role in cellular adaptation to oxidative stress.

고구마 현탁배양세포의 EST library에 높은 빈도로 존재하는 metallothionein (MT) 유전자를 선별하였다(IbMT3). MT 유전자는 세포와 조직의 스트레스 조절과 연관되어 있다고 알려져 있다. 본 연구에서 IbMT3 cDNA의 전장을 확보하여 염기서열 분석을 한 결과, IbMT3 유전자는 구조적으로 유형 3에 속하는 MT 단백질을 암호화하고 있었다. 식물에서 유형 3에 속하는 MT 단백질의 기능은 명확히 알려지지 않다. Northern blot 분석 결과, IbMT3 유전자는 고구마 식물체 잎보다 현탁배양 세포에서 매우 강하게 발현되었다. 일반적으로 세포배양은 세포에 산화 스트레스 상태를 부과하는 것으로 알려져 있다. 이에, 고구마 식물체에 산화 스트레스를 처리하여 IbMT3 유전자의 발현이 어떻게 조절되는지 조사하였다. 제초제인 methyl viologen (MV)을 6, 12, 24시간 동안 처리했을 때, IbMT3 유전자의 발현은 6시간 후에 아주 강하게 유도되었고 그 이후에는 감소함을 알 수 있었다. 저온 스트레스($15^{\circ}C$)를 24, 48시간 동안 처리했을 때, IbMT3 유전자는 처리시간이 경과함에 따라 발현이 더 많이 유도되었다. 이로써, IbMT3 유전자는 환경 및 산화 스트레스에 반응하여 발현이 조절되는 유전자임을 알 수 있었다. IbMT3 isoform은 고구마 식물체 내에서 항산화제로써 작용할 가능성이 있을 뿐 아니라, 스트레스 하에서의 세포 적응 메커니즘에 중요한 기능을 할 것으로 사료된다.

Keywords

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