Involvement of a helix-loop-helix transcription factor CHC-1 in CO2-mediated conidiation suppression in Neurospora crassa
Involvement of a helix-loop-helix transcription factor CHC-1 in CO2-mediated conidiation suppression in Neurospora crassa
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DOI：
10.1016/j.fgb.2011.09.003
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发表时间：
2011-12-01
影响因子：
3
通讯作者：
Li, Shaojie
中科院分区：
文献类型：
--
作者：
Sun, Xianyun;Zhang, Hanxing;Li, Shaojie
丝状真菌从营养生长到分生孢子的形态转换受到高度调控，但对调控机制的了解有限。本研究通过对粗枝脉孢菌103个转录因子编码基因的敲除突变体的筛选，发现一个突变体在小种管中产生丰富的分生孢子，而野生型菌株的分生孢子受到抑制。相应的基因NCU00749编码一个含有螺旋-环-螺旋DNA结合区的蛋白质。不同于ras-1和sod-1突变体的增强分生孢子完全被抗氧化剂N-乙酰半胱氨酸抑制，NCU00749突变体的增强分生孢子只受到N-乙酰半胱氨酸的轻微影响。当在斜面上生长时，NCU00749缺失突变株比野生型菌株表现出更早的分生孢子形成，这在较高的CO2浓度(5%)时更加明显。因此，我们将NCU00749命名为高二氧化碳分生孢子(CHC-1)。在分生孢子发育过程中高表达的基因eas、con6、con8和con10在CHC-1缺失突变体中的转录速率高于野生型菌株。为了确定CHC-1调节分生孢子形成的机制，我们进行了RNA测序分析，发现404个基因在CHC-1缺失后表现出-gt；=2倍的转录变化。在CHC-1缺失突变体中上调了正调控粗枝杆菌分生孢子形成的转录因子Flaffy和ada-6基因，以及在nidulans中与flbD同源基因对分生孢子形成至关重要的rca-1基因。RNA测序结果也表明，通过cAMP和MAK-2介导的信号转导以及ROS的产生和去除，这些已知调节分生孢子形成的机制，并不参与CHC-1介导的分生孢子形成的控制。此外，CHC-1还影响除分生孢子外的其他重要生物学过程中的基因表达，如碳代谢、鞘脂合成、细胞壁合成和钙信号。(C)2011 Elsevier Inc.保留所有权利。
The morphological switch from vegetative growth to conidiation in filamentous fungi is highly regulated, but the understanding of the regulatory mechanisms is limited. In this study, by screening a set of knockout mutants corresponding to 103 transcription factor encoding genes in Neurospora crassa, a mutant was found to produce abundant conidia in race tubes in which conidiation in the wild-type strain was suppressed. The corresponding gene NCU00749 encodes a protein containing a helix-loop-helix DNA binding region. Unlike enhanced conidiation in ras-1 and sod-1 mutants, which was completely suppressed by antioxidant N-acetyl cysteine, enhanced conidiation in the NCU00749 mutant was only slightly affected by N-acetyl cysteine. When grown on slants, the NCU00749 deletion mutant exhibited earlier conidial formation than the wild-type strain, and this was more evident at a higher (5%) CO2 concentration. Therefore, we named NCU00749 as conidiation at high carbon dioxide-1 (chc-1). Genes that are highly expressed during conidial development, eas, con-6, con-8 and con-10, were transcribed at a higher rate in the chc-1 deletion mutant than the wild-type strain in response to conidiation induction. To determine the mechanisms by which CHC-1 regulates conidiation, we conducted a RNA sequencing analysis and found that 404 genes exhibited >= 2 fold changes in transcription in response to chc-1 deletion. Among them, fluffy and ada-6, two transcription factor genes that positively regulate conidiation in N. crassa, and rca-1, whose homolog flbD in Aspergillus nidulans is essential for conidiation, were upregulated in the chc-1 deletion mutant. Results of RNA sequencing also suggest that signal transduction via the cAMP and the MAK-2 mediated signal pathways, and ROS generation and removal, mechanisms known to regulate conidiation, are not involved in chc-1 mediated control of conidiation. In addition, chc-1 also influences expression of genes involved in other important biological processes besides conidiation such as carbon metabolism, sphingolipid synthesis, cell wall synthesis, and calcium signaling. (C) 2011 Elsevier Inc. All rights reserved.