The phenylacetic acid uptake system of Aspergillus nidulans is under a creA-independent model of catabolic repression which seems to be mediated by acetyl-CoA
The phenylacetic acid uptake system of Aspergillus nidulans is under a creA-independent model of catabolic repression which seems to be mediated by acetyl-CoA
复制标题
DOI：
10.7164/antibiotics.50.45
复制
发表时间：
1997-01-01
影响因子：
3.3
通讯作者：
Luengo, JM
中科院分区：
文献类型：
--
作者：
FernandezCanon, JM;Luengo, JM
丝状真菌构巢曲霉能够以苯乙酸（PhAc）作为唯一碳源生长，并且具有一个高度特异性的苯乙酸转运系统来介导这种芳香族化合物的摄取。这个转运系统也能够转运一些苯氧乙酸（PhOAc），尽管效率较低。在37℃、50 mM磷酸盐缓冲液（pH 7.0）中观察到最大摄取速率。在这些条件下，摄取至少在1分钟内呈线性，苯乙酸和苯氧乙酸的Km值分别为74 μM和425 μM。苯乙酸转运系统受到苯乙酸的强烈诱导，在较小程度上受到苯氧乙酸和其他苯基衍生物的诱导。葡萄糖（和其他糖类）、甘油或乙酸盐的利用会导致摄取大幅减少。某些碳源引起的这种负面影响与creA基因无关，creA基因是介导碳分解代谢物阻遏的调节基因。编码乙酰辅酶A合成酶的基因发生功能缺失突变可防止乙酸盐的负调控，这强烈表明这种调控是由细胞内的乙酰辅酶A库介导的。
The filamentous fungus Aspergillus nidulans is able to grow on phenylacetic acid (PhAc) as the sole carbon source and has a highly specific phenylacetic acid transport system mediating the uptake of this aromatic compound. This transport system is also able to transport some phenoxyacetic acid (PhOAc), although less efficiently. Maximal uptake rates were observed at 37 degrees C in 50 mM phosphate buffer (pH 7.0). Under these conditions, uptake was linear for at least 1 minute, with Km values for PhAc and PhOAc of 74 and 425 mu M, respectively. The PhAc transport system is strongly induced by PhAc and, to a lesser extent by PhOAc and other phenyl derivatives. The utilization of glucose (and other sugars), glycerol or acetate results in a substantially reduced uptake. This negative effect caused by certain carbon sources is independent of the creA gene, the regulatory gene mediating carbon catabolite repression. Negative regulation by acetate is prevented by a loss-of-function mutation in the gene encoding acetyl-CoA synthetase, strongly suggesting that this regulation is mediated by the intracellular pool of acetyl-CoA.