Hierarchical recognition of amino acid co-germinants during Clostridioides difficile spore germination
Hierarchical recognition of amino acid co-germinants during Clostridioides difficile spore germination
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DOI：
10.1016/j.anaerobe.2017.12.001
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发表时间：
2018-02-01
期刊：
影响因子：
2.3
通讯作者：
Sorg, Joseph A.
中科院分区：
文献类型：
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作者：
Shrestha, Ritu;Sorg, Joseph A.
胆汁酸是艰难梭菌孢子萌发的重要信号；然而，仅胆汁酸信号是不够的。氨基酸，例如甘氨酸，是艰难梭菌孢子萌发所需的另一个信号。先前对发芽所需氨基酸信号的研究表明，优先选择用作发芽信号的氨基酸。之前我们发现D-丙氨酸在37℃下可以作为艰难梭菌孢子的共发芽剂，但在25℃下则不能。在这里，我们测试了其他氨基酸在37℃下与牛磺胆酸盐（TA）作为共发芽剂的能力，发现许多以前被归类为非共发芽剂的氨基酸在37℃下是共发芽剂。基于两种不同的计算的EC50值菌株中，我们发现艰难梭菌孢子以不同的效率识别不同的氨基酸。利用这些数据，我们根据氨基酸对发芽的影响对氨基酸进行排名，发现除了 D-丙氨酸之外，其他 D-形式的氨基酸也被艰难梭菌孢子用作共发芽剂。在不同类型的氨基酸中，具有支链的氨基酸如缬氨酸、亮氨酸和异亮氨酸是最差的共萌发剂。然而，甘氨酸仍然是这两种菌株最有效的氨基酸信号。我们的结果表明，尚未鉴定的氨基酸起始受体是高度混杂的。 (C) 2017 Elsevier Ltd. 保留所有权利。
Bile acids are an important signal for germination of Clostridioides difficile spores; however, the bile acid signal alone is not sufficient. Amino acids, such as glycine, are another signal necessary for germination by C. difficile spores. Prior studies on the amino acid signal required for germination have shown that there is a preference for the amino acid used as a signal for germination. Previously we found that D-alanine can function as a co-germinant for C. difficile spores at 37 degrees C but not at 25 degrees C. Here, we tested the ability of other amino acids to act as co-germinants with taurocholate (TA) at 37 degrees C and found that many amino acids previously categorized as non-co-germinants are co-germinants at 37 degrees C. Based on the EC50 values calculated for two different strains, we found that C. difficile spores recognize different amino acids with varying efficiencies. Using this data, we ranked the amino acids based on their effect on germination and found that in addition to D-alanine, other D-forms of amino acids are also used by C. difficile spores as co-germinants. Among the different types of amino acids, ones with branched chains such as valine, leucine, and isoleucine are the poorest co-germinants. However, glycine is still the most effective amino acid signal for both strains. Our results suggest that the yet-to-be-identified amino acid germinant receptor is highly promiscuous. (C) 2017 Elsevier Ltd. All rights reserved.