Involvement of a G Protein Regulatory Circuit in Alternative Oxidase Production in Neurospora crassa
Involvement of a G Protein Regulatory Circuit in Alternative Oxidase Production in Neurospora crassa
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DOI：
10.1534/g3.119.400522
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发表时间：
2019-10-01
影响因子：
2.6
通讯作者：
Nargang, Frank E.
中科院分区：
文献类型：
--
作者：
Bosnjak, Natasa;Smith, Kristina M.;Nargang, Frank E.
粗糙脉孢菌核aod-1基因编码在线粒体中起作用的替代氧化酶。该酶通过将电子直接从泛醇转移到氧而提供标准电子传递链的分支。在标准的实验室菌株中，aod-1在正常生长条件下以非常低的水平转录。然而，如果标准的电子传递链被破坏，aod-1 mRNA的表达被诱导和AOD 1蛋白的产生。我们以前鉴定了一株N. crassa，其在非诱导条件下产生高水平的aod-1转录物。在这里，我们将该菌株与标准实验室菌株杂交，并确定了亲本和几个后代的基因组序列。未诱导培养物中aod-1 mRNA的序列数据和水平的分析显示，flbA基因中的移码突变导致aod-1的高未诱导表达。flbA基因编码G蛋白信号传导的调节剂，其降低异源三聚体G蛋白的G α亚基的活性。我们的数据表明，具有功能flbA基因的菌株通过灭活G蛋白信号通路来防止aod-1的未诱导表达，并且该通路在诱导aod-1的条件下生长的细胞中被激活。缺失G α蛋白编码基因的诱导细胞中aod-1 mRNA水平仍有部分增加，提示在N.粗鲁。我们还提出的证据表明，翻译控制机制，防止生产的AOD 1蛋白在未诱导的文化。
The Neurospora crassa nuclear aod-1 gene encodes an alternative oxidase that functions in mitochondria. The enzyme provides a branch from the standard electron transport chain by transferring electrons directly from ubiquinol to oxygen. In standard laboratory strains, aod-1 is transcribed at very low levels under normal growth conditions. However, if the standard electron transport chain is disrupted, aod-1 mRNA expression is induced and the AOD1 protein is produced. We previously identified a strain of N. crassa, that produces high levels of aod-1 transcript under non-inducing conditions. Here we have crossed this strain to a standard lab strain and determined the genomic sequences of the parents and several progeny. Analysis of the sequence data and the levels of aod-1 mRNA in uninduced cultures revealed that a frameshift mutation in the flbA gene results in the high uninduced expression of aod-1. The flbA gene encodes a regulator of G protein signaling that decreases the activity of the G alpha subunit of heterotrimeric G proteins. Our data suggest that strains with a functional flbA gene prevent uninduced expression of aod-1 by inactivating a G protein signaling pathway, and that this pathway is activated in cells grown under conditions that induce aod-1. Induced cells with a deletion of the gene encoding the G alpha protein still have a partial increase in aod-1 mRNA levels, suggesting a second pathway for inducing transcription of the gene in N. crassa. We also present evidence that a translational control mechanism prevents production of AOD1 protein in uninduced cultures.