Chroumpi Tania, Aguilar-Pontes Maria Victoria, Peng Mao, Wang Mei, Lipzen Anna, Ng Vivian, Grigoriev Igor V, Mäkelä Miia R, de Vries Ronald P
Fungal Physiology, Westerdijk Fungal Biodiversity Institute & Fungal Molecular Physiology, Utrecht University, Uppsalalaan 8, 3584 CT, Utrecht, the Netherlands.
DOE Joint Genome Institute, 2800 Mitchell Drive, Walnut Creek, CA 94598, United States.
Microbiol Res. 2020 Feb 7;234:126426. doi: 10.1016/j.micres.2020.126426.
In fungi, L-rhamnose (Rha) is converted via four enzymatic steps into pyruvate and L-lactaldehyde, which enter central carbon metabolism. In Aspergillus niger, only the genes involved in the first three steps of the Rha catabolic pathway have been identified and characterized, and the inducer of the pathway regulator RhaR remained unknown. In this study, we identified the gene (lkaA) involved in the conversion of L-2-keto-3-deoxyrhamnonate (L-KDR) into pyruvate and L-lactaldehyde, which is the last step of the Rha pathway. Deletion of lkaA resulted in impaired growth on L-rhamnose, and potentially in accumulation of L-KDR. Contrary to ΔlraA, ΔlrlA and ΔlrdA, the expression of the Rha-responsive genes that are under control of RhaR, were at the same levels in ΔlkaA and the reference strain, indicating the role of L-KDR as the inducer of the Rha pathway regulator.
在真菌中，L-鼠李糖（Rha）通过四个酶促步骤转化为丙酮酸和L-乳醛，它们进入中心碳代谢。在黑曲霉中，仅鉴定并表征了参与Rha分解代谢途径前三个步骤的基因，而该途径调节因子RhaR的诱导物仍然未知。在本研究中，我们鉴定了参与将L-2-酮-3-脱氧鼠李糖酸（L-KDR）转化为丙酮酸和L-乳醛的基因（lkaA），这是Rha途径的最后一步。lkaA的缺失导致在L-鼠李糖上生长受损，并可能导致L-KDR积累。与ΔlraA、ΔlrlA和ΔlrdA相反，受RhaR控制的Rha反应基因在ΔlkaA和参考菌株中的表达水平相同，表明L-KDR作为Rha途径调节因子的诱导物的作用。
