Conjugative Plasmid from Lactobacillus gasseri LA39 That Carries Genes for Production of and Immunity to the Circular Bacteriocin Gassericin A
Conjugative Plasmid from Lactobacillus gasseri LA39 That Carries Genes for Production of and Immunity to the Circular Bacteriocin Gassericin A
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DOI：
10.1128/aem.00195-09
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发表时间：
2009-10-01
影响因子：
4.4
通讯作者：
Saito, Tadao
中科院分区：
文献类型：
--
作者：
Ito, Yoshiyuki;Kawai, Yasushi;Saito, Tadao
Gassericin A是由Lactobacillus gasseri菌株LA 39产生的环状细菌素。我们在该菌株中发现了一个33，333-bp的质粒，命名为pLgLA 39。pLgLA 39含有44个开放阅读框，包括7个与gassericin A产生/免疫（gaa）相关的基因，以及用于复制、质粒维持和接合转移的基因。将pLgLA 39从LA 39转移到L. gasseri（JCM 1131）过滤器匹配。接合子对加丝菌素A的抗性提高了30倍以上，并产生了抗菌活性。路氏乳杆菌LA 6是路氏菌素6的产生菌，它含有一个与pLgLA 39无区别的质粒，并携带7个与gaa 100%相同的基因。这表明pLgLA 39可能在L. gasseri LA 39和L. reuteri LA6.将pLgLA 39的7个gaa基因克隆到质粒载体中以构建pGAA。JCM 1131（T）经pGAA转化后表现出抗菌活性和对gassericin A的抗性。pGAA在分离上比缺失gaaA的pGAA衍生质粒更稳定，甚至比载体更稳定。这表明gaa基因对分离后宿主的杀伤作用。pLgLA 39携带pemIK同源物，并且还证实了pLgLA 39型pemIK基因对质粒的分离稳定性。因此，pLgLA 39被证明携带至少两种质粒维持机制的基因，即，gaa和pemIK。含有与pLgLA 39 repA基因相似的repA基因的质粒在几种L. gasseri菌株
Gassericin A is a circular bacteriocin produced by Lactobacillus gasseri strain LA39. We found a 33,333-bp plasmid, designated pLgLA39, in this strain. pLgLA39 contained 44 open reading frames, including seven genes related to gassericin A production/immunity (gaa), as well as genes for replication, plasmid maintenance, and conjugative transfer. pLgLA39 was transferred from LA39 to the type strain of L. gasseri (JCM 1131) by filter mating. The transconjugant exhibited >30-fold-higher more resistance to gassericin A and produced antibacterial activity. Lactobacillus reuteri LA6, the producer of reutericin 6, was proved to harbor a plasmid indistinguishable from pLgLA39 and carrying seven genes 100% identical to gaa. This suggests that pLgLA39 might have been transferred naturally between L. gasseri LA39 and L. reuteri LA6. The seven gaa genes of pLgLA39 were cloned into a plasmid vector to construct pGAA. JCM 1131(T) transformed with pGAA expressed antibacterial activity and resistance to gassericin A. pGAA was segregationally more stable than a pGAA derivative plasmid from which gaaA was deleted and even was more stable than the vector. This suggests the occurrence of postsegregational host killing by the gaa genes. pLgLA39 carried a pemIK homolog, and segregational stabilization of a plasmid by the pLgLA39-type pemIK genes was also confirmed. Thus, pLgLA39 was proved to carry the genes for at least two plasmid maintenance mechanisms, i.e., gaa and pemIK. Plasmids containing a repA gene similar to pLgLA39 repA were distributed in several L. gasseri strains.