Novel stand-alone RAM domain protein-mediated catalytic control of anthranilate phosphoribosyltransferase in tryptophan biosynthesis in Thermus thermophilus

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• 作者：Tetsuo Kubota ; Hajime Matsushita ; Takeo Tomita ; Saori Kosono…
• 关键词：RAM domain ; Tryptophan biosynthesis ; Anthranilate phosphoribosyltransferase ; Feedback inhibition ; Thermus thermophilus
• 刊名：Extremophiles
• 出版年：2017
• 出版时间：January 2017
• 年：2017
• 卷：21
• 期：1
• 页码：73-83
• 全文大小：1102KB
• 刊物类别：Biomedical and Life Sciences
• 刊物主题：Microbiology; Biotechnology; Biochemistry, general; Microbial Ecology;
• 出版者：Springer Japan
• ISSN：1433-4909
• 卷排序：21

文摘

Regulation of amino acid metabolism (RAM) domains are widely distributed among prokaryotes. In most cases, a RAM domain fuses with a DNA-binding domain to act as a transcriptional regulator. The extremely thermophilic bacterium, Thermus thermophilus, only carries a single gene encoding a RAM domain-containing protein on its genome. This protein is a stand-alone RAM domain protein (SraA) lacking a DNA-binding domain. Therefore, we hypothesized that SraA, which senses amino acids through its RAM domain, may interact with other proteins to modify its functions. In the present study, we identified anthranilate phosphoribosyltransferase (AnPRT), the second enzyme in the tryptophan biosynthetic pathway, as a partner protein that interacted with SraA in T. thermophilus. In the presence of tryptophan, SraA was assembled to a decamer and exhibited the ability to form a stable hetero-complex with AnPRT. An enzyme assay revealed that AnPRT was only inhibited by tryptophan in the presence of SraA. This result suggests a novel feedback control mechanism for tryptophan biosynthesis through an inter-RAM domain interaction in bacteria.