Role of Branched-Chain Amino Acid Transport in Bacillus subtilis CodY Activity
Role of Branched-Chain Amino Acid Transport in Bacillus subtilis CodY Activity
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DOI：
10.1128/jb.02563-14
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发表时间：
2015-04-01
影响因子：
3.2
通讯作者：
Belitsky, Boris R.
中科院分区：
文献类型：
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作者：
Belitsky, Boris R.
CodY是一种支链氨基酸响应性转录调节因子，控制枯草芽孢杆菌中几十个转录单位的表达。生长培养基中异亮氨酸、缬氨酸和亮氨酸的存在对于实现CodY的高活性和有效调节靶基因是必不可少的。我们确定了三个permeases-BcaP，BraB和BrnQ-这是负责大部分的异亮氨酸和缬氨酸的摄取，也参与亮氨酸的摄取。至少另一种通透酶能够有效摄取亮氨酸，以及低亲和力转运异亮氨酸和缬氨酸。前三个渗透酶的缺乏强烈降低了CodY在含氨基酸的生长培养基中的活性。BcaP似乎是最有效的异亮氨酸和缬氨酸通透酶负责他们的利用作为氮源。先前描述的强CodY介导的BcaP抑制提供了一种通过减少氨基酸的可用性来微调CodY活性的机制，以及在营养过剩的条件下延迟异亮氨酸和缬氨酸作为氮源和碳源的利用的机制。
CodY is a branched-chain amino acid-responsive transcriptional regulator that controls the expression of several dozen transcription units in Bacillus subtilis. The presence of isoleucine, valine, and leucine in the growth medium is essential for achieving high activity of CodY and for efficient regulation of the target genes. We identified three permeases-BcaP, BraB, and BrnQ-that are responsible for the bulk of isoleucine and valine uptake and are also involved in leucine uptake. At least one more permease is capable of efficient leucine uptake, as well as low-affinity transport of isoleucine and valine. The lack of the first three permeases strongly reduced activity of CodY in an amino acid-containing growth medium. BcaP appears to be the most efficient isoleucine and valine permease responsible for their utilization as nitrogen sources. The previously described strong CodY-mediated repression of BcaP provides a mechanism for fine-tuning CodY activity by reducing the availability of amino acids and for delaying the utilization of isoleucine and valine as nitrogen and carbon sources under conditions of nutrient excess.