The highly expressed methionine synthase gene of Neurospora crassa is positively regulated by its proximal heterochromatic region.
In Neurospora crassa, the methionine synthase gene met-8 plays a key role in methionine synthesis. In this study, we found that MET-8 protein levels were compromised in several mutants defective in proper heterochromatin formation. Bioinformatics analysis revealed a 50-kb AT-rich region adjacent to the met-8 promoter. ChIP assays confirmed that trimethylated H3K9 was enriched in this region, indicating that heterochromatin may form upstream of met-8. In an H3K9R mutant strain, the output of met-8 was dramatically reduced, similar to what we observed in mutant strains that had defective heterochromatin formation. Furthermore, the production of ectopically expressed met-8 at the his-3 locus in the absence of a normal heterochromatin environment was inefficient, whereas ectopic expression of met-8 downstream of two other heterochromatin domains was efficient. In addition, our data show that the expression of mig-6 was also controlled by an upstream 4.2-kb AT-rich region similar to that of the met-8 gene, and we demonstrate that the AT-rich regions adjacent to met-8 or mig-6 are required for their peak expression. Our study indicates that met-8 and mig-6 may represent a novel type of gene, whose expression relies on the proper formation of a nearby heterochromatin region.
State Key Laboratory of Agro-biotechnology and MOA Key Laboratory of Soil Microbiology, College of Biological Sciences, China Agricultural University, Beijing 100193, China.
Silu
S
Yang
Institute of Basic Medical Sciences, National Center of Biomedical Analysis, Beijing 100850, China.
Weihua
W
Li
State Key Laboratory of Agro-biotechnology and MOA Key Laboratory of Soil Microbiology, College of Biological Sciences, China Agricultural University, Beijing 100193, China.
Shaohua
S
Qi
State Key Laboratory of Agro-biotechnology and MOA Key Laboratory of Soil Microbiology, College of Biological Sciences, China Agricultural University, Beijing 100193, China.
Kexin
K
Gai
Photosynthesis Research Center, Key Laboratory of Photobiology, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China.
Yibo
Y
Chen
State Key Laboratory of Agro-biotechnology and MOA Key Laboratory of Soil Microbiology, College of Biological Sciences, China Agricultural University, Beijing 100193, China.
Jingxia
J
Suo
State Key Laboratory of Agro-biotechnology and MOA Key Laboratory of Soil Microbiology, College of Biological Sciences, China Agricultural University, Beijing 100193, China.
Yingqiong
Y
Cao
Beijing Zhong Guan Cun High School, Beijing 100086, China.
Yubo
Y
He
State Key Laboratory of Agro-biotechnology and MOA Key Laboratory of Soil Microbiology, College of Biological Sciences, China Agricultural University, Beijing 100193, China.
Ying
Y
Wang
State Key Laboratory of Agro-biotechnology and MOA Key Laboratory of Soil Microbiology, College of Biological Sciences, China Agricultural University, Beijing 100193, China qunhe@cau.edu.cn.
Qun
Q
He
D020121:5' Untranslated Regions; D013766:5-Methyltetrahydrofolate-Homocysteine S-Methyltransferase / Q000235:genetics* / Q000378:metabolism; D005656:Fungal Proteins / Q000235:genetics* / Q000378:metabolism; D017353:Gene Deletion; D015966:Gene Expression Regulation, Fungal; D006570:Heterochromatin / Q000378:metabolism*; D000076983:Histone Methyltransferases; D011495:Histone-Lysine N-Methyltransferase / Q000235:genetics; D006657:Histones / Q000378:metabolism; D009492:Neurospora crassa / Q000201:enzymology / Q000235:genetics* / Q000378:metabolism; D012319:RNA Polymerase II / Q000378:metabolism
D020121:5' Untranslated Regions; D005656:Fungal Proteins; D006570:Heterochromatin; D006657:Histones; D000076983:Histone Methyltransferases; D013766:5-Methyltetrahydrofolate-Homocysteine S-Methyltransferase; D011495:Histone-Lysine N-Methyltransferase; D012319:RNA Polymerase II