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首页> 外文期刊>Journal of bacteriology >Sialic Acid (N-Acetyl Neuraminic Acid) Utilization by Bacteroides fragilis Requires a Novel N-Acetyl Mannosamine Epimerase
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Sialic Acid (N-Acetyl Neuraminic Acid) Utilization by Bacteroides fragilis Requires a Novel N-Acetyl Mannosamine Epimerase

机译：脆弱拟杆菌利用唾液酸（N-乙酰神经氨酸）需要一种新型N-乙酰甘露糖胺差向异构酶

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摘要

We characterized the nanLET operon in Bacteroides fragilis, whose products are required for the utilization of the sialic acid N-acetyl neuraminic acid (NANA) as a carbon and energy source. The first gene of the operon is nanL, which codes for an aldolase that cleaves NANA into N-acetyl mannosamine (manNAc) and pyruvate. The next gene, nanE, codes for a manNAc/N-acetylglucosamine (NAG) epimerase, which, intriguingly, possesses more similarity to eukaryotic renin binding proteins than to other bacterial NanE epimerase proteins. Unphosphorylated manNAc is the substrate of NanE, while ATP is a cofactor in the epimerase reaction. The third gene of the operon is nanT, which shows similarity to the major transporter facilitator superfamily and is most likely to be a NANA transporter. Deletion of any of these genes eliminates the ability of B. fragilis to grow on NANA. Although B. fragilis does not normally grow with manNAc as the sole carbon source, we isolated a B. fragilis mutant strain that can grow on this substrate, likely due to a mutation in a NAG transporter; both manNAc transport and NAG transport are affected in this strain. Deletion of the nanE epimerase gene or the rokA hexokinase gene, whose product phosphorylates NAG, in the manNAc-enabled strain abolishes growth on manNAc. Thus, B. fragilis possesses a new pathway of NANA utilization, which we show is also found in other Bacteroides species.
机译：我们对脆弱的拟杆菌（Bacteroides fragilis）的 nanLET 操纵子进行了表征，其产物是利用唾液酸 N-乙酰神经氨酸（NANA）所必需的。碳和能源。操纵子的第一个基因是 nanL ，其编码的醛缩酶可将NANA裂解为 N -乙酰甘露糖胺（manNAc）和丙酮酸。下一个基因， nanE ，编码一种manNAc / N -乙酰氨基葡萄糖（NAG）差向异构酶，有趣的是，它与真核肾素结合蛋白比其他细菌NanE具有更多相似性。差向异构酶蛋白。未磷酸化的manNAc是NanE的底物，而ATP是差向异构酶反应的辅助因子。操纵子的第三个基因是 nanT ，与主要的转运蛋白易化子超家族相似，最有可能是NANA转运蛋白。这些基因中任何一个的缺失消除了 B的能力。脆弱的人在NANA上成长。虽然 B。易碎的通常不会以manNAc作为唯一的碳源生长，我们分离出了 B。可能是由于NAG转运蛋白的突变而在该底物上生长的脆弱类突变菌株; manNAc转运和NAG转运都受到该菌株的影响。在具有manNAc功能的菌株中，删除 nanE 差向异构酶基因或 rokA 己糖激酶基因（其产物使NAG磷酸化）消除了manNAc的生长。因此， B。脆弱类植物具有新的NANA利用途径，我们证明了它也在其他细菌类中发现。

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