Endogenous CRISPR-Cas Systems in Group I Clostridium botulinum and Clostridium sporogenes Do Not Directly Target the Botulinum Neurotoxin Gene Cluster.
Endogenous CRISPR-Cas Systems in Group I Clostridium botulinum and Clostridium sporogenes Do Not Directly Target the Botulinum Neurotoxin Gene Cluster.
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DOI：
10.3389/fmicb.2021.787726
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发表时间：
2021
影响因子：
5.2
通讯作者：
Pellett S
中科院分区：
文献类型：
--
作者：
Wentz TG;Tremblay BJM;Bradshaw M;Doxey AC;Sharma SK;Sauer JD;Pellett S
蛋白水解型肉毒梭菌(G1C)的大部分菌株和部分生孢梭菌都含有肉毒杆菌神经毒素(BONT)基因。在G1肉毒杆菌中，三种主要毒素血清型(BONT/A/B/F)的保守的BONT基因簇可以在接合质粒上和/或在染色体致病岛上找到。CRISPR-CAS系统通过创建与MGES内的Protspacers互补的间隔库，实现了对先前遇到的移动遗传元件(MGE)的定点靶向，例如质粒和噬菌体。为了检验内源性CRISPR-Cas系统是否限制了BONT基因簇在菌株之间的转移，我们对241株G1肉毒杆菌和产孢杆菌的内源CRISPR-Cas系统进行了生物信息学分析。在所有菌株中鉴定出约6,200个CRISPR间隔区，83%的菌株鉴定出I-B型、III-A/B/D型cas基因和CRISPR阵列特征。将预测的间隔区与掩蔽菌株和RefSeq质粒数据集进行比对，确定了56,000个间隔区-蛋白间隔区匹配。虽然间隔区大量映射到BONT(+)质粒内的靶标，但在BONT基因簇中没有发现任何原扩增子。这些结果表明，该毒素不是CRISPR-Cas的直接靶标，但主要负责其动员的质粒是。最后，虽然CRISPR-Cas系统的存在并不能可靠地表明BONT基因簇的存在或不存在，但跨菌株的比较基因组学表明，它们经常占据两个物种共同的相同的高变量基因座，这可能表明两个基因组特征的获取和管理涉及类似的机制。
Most strains of proteolytic group I Clostridium botulinum (G1 C. botulinum) and some strains of Clostridium sporogenes possess genes encoding botulinum neurotoxin (BoNT), a potent neuroparalytic agent. Within G1 C. botulinum, conserved bont gene clusters of three major toxin serotypes (bont/A/B/F) can be found on conjugative plasmids and/or within chromosomal pathogenicity islands. CRISPR-Cas systems enable site-specific targeting of previously encountered mobile genetic elements (MGE) such as plasmids and bacteriophage through the creation of a spacer library complementary to protospacers within the MGEs. To examine whether endogenous CRISPR-Cas systems restrict the transfer of bont gene clusters across strains we conducted a bioinformatic analysis profiling endogenous CRISPR-Cas systems from 241 G1 C. botulinum and C. sporogenes strains. Approximately 6,200 CRISPR spacers were identified across the strains and Type I-B, III-A/B/D cas genes and CRISPR array features were identified in 83% of the strains. Mapping the predicted spacers against the masked strain and RefSeq plasmid dataset identified 56,000 spacer–protospacer matches. While spacers mapped heavily to targets within bont(+) plasmids, no protospacers were identified within the bont gene clusters. These results indicate the toxin is not a direct target of CRISPR-Cas but the plasmids predominantly responsible for its mobilization are. Finally, while the presence of a CRISPR-Cas system did not reliably indicate the presence or absence of a bont gene cluster, comparative genomics across strains indicates they often occupy the same hypervariable loci common to both species, potentially suggesting similar mechanisms are involved in the acquisition and curation of both genomic features.
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影响因子：
2.6
作者：
Dineen, SS;Bradshaw, M;Johnson, EA
通讯作者：
Johnson, EA
影响因子：
16.6
作者：
Contreras, Estefania;Masuyer, Geoffrey;Gill, Sarjeet S.
通讯作者：
Gill, Sarjeet S.
影响因子：
14.9
作者：
Couvin D;Bernheim A;Toffano-Nioche C;Touchon M;Michalik J;Néron B;Rocha EPC;Vergnaud G;Gautheret D;Pourcel C
通讯作者：
Pourcel C
影响因子：
4.1
作者：
Biswas A;Gagnon JN;Brouns SJ;Fineran PC;Brown CM
通讯作者：
Brown CM
影响因子：
4.2
作者：
Brunt, Jason;van Vliet, Arnoud H. M.;Peck, Michael W.
通讯作者：
Peck, Michael W.