Mapping Interactions between Germinants and Clostridium difficile Spores
Mapping Interactions between Germinants and Clostridium difficile Spores
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DOI：
10.1128/jb.00980-10
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发表时间：
2011-01-01
影响因子：
3.2
通讯作者：
Abel-Santos, Ernesto
中科院分区：
文献类型：
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作者：
Howerton, Amber;Ramirez, Norma;Abel-Santos, Ernesto
艰难梭菌孢子萌发是确定艰难梭菌相关性疾病(CDAD)的第一步。牛磺胆酸盐(一种胆盐)和甘氨酸(一种氨基酸)已被证明是艰难梭菌孢子的重要萌发源。在目前的研究中，我们测试了一系列甘氨酸和牛磺胆酸盐类似物诱导或抑制艰难梭菌孢子萌发的能力。对甘氨酸类似物的测试表明，羧基和氨基都是重要的识别表位，甘氨酸结合部位可以容纳末端分离更广的化合物。艰难梭菌的发芽机制还能识别其他疏水性氨基酸。一般而言，直链烷基侧链比它们的分支类似物更能促进孢子萌发。然而，L-苯丙氨酸和L-精氨酸也是很好的发芽物质，可能是通过不同的结合位点识别的。对牛磺胆酸盐类似物的测试表明，牛磺胆酸盐的12-羟基是激活孢子萌发所必需的，但不是充分的。相反，6-羟基和7-羟基是抑制艰难梭菌孢子萌发所必需的。同样，艰难梭菌的孢子能够检测到具有较短但不是较长的烷基氨基磺酸侧链的牛磺胆酸盐类似物。此外，磺酸基团可以被其他酸性基团部分取代。最后，含有间氨基苯磺酸侧链的牛磺胆酸盐类似物对艰难梭菌的孢子萌发有很强的抑制作用。总之，艰难梭菌孢子通过多种相互作用识别氨基酸和牛磺胆酸，这些相互作用是结合发芽细胞和/或激活萌发机制所必需的。
Germination of Clostridium difficile spores is the first required step in establishing C. difficile-associated disease (CDAD). Taurocholate (a bile salt) and glycine (an amino acid) have been shown to be important germinants of C. difficile spores. In the present study, we tested a series of glycine and taurocholate analogs for the ability to induce or inhibit C. difficile spore germination. Testing of glycine analogs revealed that both the carboxy and amino groups are important epitopes for recognition and that the glycine binding site can accommodate compounds with more widely separated termini. The C. difficile germination machinery also recognizes other hydrophobic amino acids. In general, linear alkyl side chains are better activators of spore germination than their branched analogs. However, L-phenylalanine and L-arginine are also good germinants and are probably recognized by distinct binding sites. Testing of taurocholate analogs revealed that the 12-hydroxyl group of taurocholate is necessary, but not sufficient, to activate spore germination. In contrast, the 6- and 7-hydroxyl groups are required for inhibition of C. difficile spore germination. Similarly, C. difficile spores are able to detect taurocholate analogs with shorter, but not longer, alkyl amino sulfonic acid side chains. Furthermore, the sulfonic acid group can be partially substituted with other acidic groups. Finally, a taurocholate analog with an m-aminobenzenesulfonic acid side chain is a strong inhibitor of C. difficile spore germination. In conclusion, C. difficile spores recognize both amino acids and taurocholate through multiple interactions that are required to bind the germinants and/or activate the germination machinery.