The Korean Journal of Mycology (한국균학회지)

The Korean Society of Mycology (한국균학회)
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Gene Structure and Function of fkhE, a Forkhead Gene in a Filamentous Fungus Aspergillus nidulans

Aspergillus nidulans forkhead 유전자 fkhE의 구조와 기능 분석

  • Park, Mi-Hye (Department of Pharmaceutical Engineering, Woosuk University) ;
  • Kim, Hyoun-Young (Department of Pharmaceutical Engineering, Woosuk University) ;
  • Kim, Jong-Hwa (Department of Pharmaceutical Engineering, Woosuk University) ;
  • Han, Kap-Hoon (Department of Pharmaceutical Engineering, Woosuk University)
  • Received : 2010.12.13
  • Accepted : 2010.12.21
  • Published : 2010.12.31
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Abstract

A homothallic filamentous fungus Aspergillus nidulans has been used as the a model organism for studying growth and development for eukaryotic system. Various studies about specific transcription factors have been performed for elucidating the molecular mechanisms of growth, asexual and sexual developmental processes. Among them, the fkhE gene (AN2025.3) is located in chromosome VII and contains an ORF encoding 718 amino acid polypeptide intervening with two short introns. The cDNA sequencing revealed that at least four types of alternative splicing events were occurred when the fkhE gene was transcribed. The putative FkhE polypeptide contains a conserved forkhead domain and a bipartite nuclear localization signal at it's N-terminus and C-terminus, respectively. Deletion of fkhE resulted in impaired conidiophore formation in a solid medium. However, the sexual developmental process or cleistothecia formation was normal. Furthermore, fkhE deletion mutant produced conidiophores and conidia under the submerged culture, indicating that the fkhE gene is involved in asexual developmental process similar to the fkhF gene.

모델 사상성 진균 Aspergillus nidulans는 분화과정을 연구하는 진핵세포 시스템으로 사용되어 왔다. 이러한 분화과정은 매우 다양한 유전자들의 발현을 통하여 조절되며 이와 관련된 다양한 전사요소들의 기능이 연구되어 왔다. 이들 중 forkhead 유전자는 일반적으로 감수분열 및 세포주기 조절에 중요한 역할을 하는 것으로 알려져 왔으며 A. nidulans에서도 유사한 기능을 하리라 예상되어 왔다. 이와 관련된 연구를 위하여 A. nidulans 유전체에 존재하는 6개의 forkhead 유전자를 발견, 확보하였고, 최근에는 효모 및 다른 진균에서는 발견되지 않는 A. nidulans 특이적 forkhead 유전자인 fkhF의 구조와 기능이 분석된 바 있다. 본 연구에서는 fkhF와 매우 유사한 단백질 서열을 가지고 있는 fkhE(AN2025.3) 유전자의 기능을 분석하였다. 본 유전자의 기능을 분석하기 위해 RT-PCR을 통하여 cDNA 서열을 분석한 결과 약 3종류의 서로 다른 mRNA가 존재하는 것이 밝혀졌고 이는 alternative splicing에 의한 것으로 추정되었다. 이들 3종류의 mRNA중 한 종류만 정상적인 ORF를 가지고 있으며 조사한 전체 cDNA 발현의 61%를 차지하였다. fkhE 유전자는 718개의 아미노산을 암호화하는 하나의 ORF를 가지고 있었으며 N 말단에 보존된 forkhead 도메인을 가지고 있었다. fkhE 유전자를 제거한 유전자 제거 돌연변이 균주는 fkhF와 유사하게 고체배지에서는 무성포자의 형성이 저해되었으나 유성분화에는 별다른 영향을 미치지 않았으며 액체 진탕배양에서는 야생형과 다르게 무성포자병(conidiophore)이 형성되었다. 이러한 결과는 fkhE 유전자가 무성분화에 관련되었음을 보여준다.

Keywords

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