Association with AflR in Endosomes Reveals New Functions for AflJ in Aflatoxin Biosynthesis

Toxins

Kenneth C. Ehrlich¹  Brian M. Mack¹  Qijian Wei¹  Ping Li¹  Ludmila V. Roze²  Frank Dazzo³  Jeffrey W. Cary¹  Deepak Bhatnagar¹ 

[1] Southern Regional Research Center, Agricultural Research Service/United States Department of Agriculture, 1100 Robert E. Lee Blvd, New Orleans, LA 70124, USA; E-Mails:;Department of Food Science and Human Nutrition, Michigan State University, East Lansing, MI 488244, USA; E-Mails:;Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, MI 488244, USA; E-Mail:

关键词: aflatoxin;    protein trafficking;    Aspergillus parasiticus;    aflatoxin;    aflatoxisomes;    endosomes;    AflJ;    AflR;   

DOI  :  10.3390/toxins4121582

来源: mdpi

【 摘 要 】

Aflatoxins are the most potent naturally occurring carcinogens of fungal origin. Biosynthesis of aflatoxin involves the coordinated expression of more than 25 genes. The function of one gene in the aflatoxin gene cluster, aflJ, is not entirely understood but, because previous studies demonstrated a physical interaction between the Zn₂Cys₆ transcription factor AflR and AflJ, AflJ was proposed to act as a transcriptional co-activator. Image analysis revealed that, in the absence of aflJ in A. parasiticus, endosomes cluster within cells and near septa. AflJ fused to yellow fluorescent protein complemented the mutation in A. parasiticus ΔaflJ and localized mainly in endosomes. We found that AflJ co-localizes with AflR both in endosomes and in nuclei. Chromatin immunoprecipitation did not detect AflJ binding at known AflR DNA recognition sites suggesting that AflJ either does not bind to these sites or binds to them transiently. Based on these data, we hypothesize that AflJ assists in AflR transport to or from the nucleus, thus controlling the availability of AflR for transcriptional activation of aflatoxin biosynthesis cluster genes. AflJ may also assist in directing endosomes to the cytoplasmic membrane for aflatoxin export.

【 授权许可】

CC BY   
© 2012 by the authors; licensee MDPI, Basel, Switzerland.