Biomolecular Engineering Laboratory, School of Food and Nutritional Science, University of Shizuoka, Suruga-ku, Shizuoka, Japan.
Laboratory of Food Chemistry, School of Food and Nutritional Science, University of Shizuoka, Suruga-ku, Shizuoka, Japan.
Biosci Biotechnol Biochem. 2021 Feb 18;85(2):452-463. doi: 10.1093/bbb/zbaa030.
The uptake of di/tripeptides is mediated by the proton-dependent oligopeptide transporter (POT) family. In this study, 3 POT family transporters, designated PotA, PotB, and PotC were identified in Aspergillus oryzae. Growth comparison of deletion mutants of these transporter genes suggested that PotB and PotC are responsible for di/tripeptide uptake. PotA, which had the highest sequence similarity to yeast POT (Ptr2), contributed little to the uptake. Nitrogen starvation induced potB and potC expression, but not potA expression. When 3 dipeptides were provided as nitrogen sources, the expression profiles of these genes were different. PrtR, a transcription factor that regulates proteolytic genes, was involved in regulation of potA and potB but not in potC expression. Only potC expression levels were dramatically reduced by disruption of ubrA, an orthologue of yeast ubiquitin ligase UBR1 responsible for PTR2 expression. Expression of individual POT genes is apparently controlled by different regulatory mechanisms.
二肽/三肽的摄取是由质子依赖的寡肽转运蛋白（POT）家族介导的。在这项研究中，从米曲霉中鉴定出 3 种 POT 家族转运蛋白，分别命名为 PotA、PotB 和 PotC。这些转运蛋白基因缺失突变体的生长比较表明，PotB 和 PotC 负责二肽/三肽的摄取。PotA 与酵母 POT（Ptr2）的序列相似度最高，但对摄取的贡献很小。氮饥饿诱导 potB 和 potC 的表达，但不诱导 potA 的表达。当提供 3 种二肽作为氮源时，这些基因的表达谱不同。调控蛋白酶基因的转录因子 PrtR 参与调控 potA 和 potB，但不参与 potC 的表达。只有破坏 ubrA（酵母泛素连接酶 UBR1 的同源物）后，potC 的表达水平才会显著降低，ubrA 负责 PTR2 的表达。单个 POT 基因的表达显然受到不同调控机制的控制。
