DNA Sequencing and Homologous Expression of a Small Peptide Conferring Immunity to Gassericin A, a Circular Bacteriocin Produced by Lactobacillus gasseri LA39
DNA Sequencing and Homologous Expression of a Small Peptide Conferring Immunity to Gassericin A, a Circular Bacteriocin Produced by Lactobacillus gasseri LA39
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DOI：
10.1128/aem.02485-08
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发表时间：
2009-03-01
影响因子：
4.4
通讯作者：
Saito, Tadao
中科院分区：
文献类型：
--
作者：
Kawai, Yasushi;Kusnadi, Joni;Saito, Tadao
Gassericin A是由Lactobacillus gasseri LA 39产生的一种疏水环状细菌素。对gassericin A结构基因gaaA周围的DNA区域进行了测序，发现了7个3.5 kbp的开放阅读框（gaaBCADITE），它们可能在gassericin A的产生、分泌和免疫中起作用。5个连续ORF gaaADITE的推导产物与参与丁酸弧菌素AR 10生产的基因具有同源性，尽管两个环状细菌素基因的遗传排列不同。半乳糖苷是一种53个氨基酸的小的带正电荷的疏水肽，含有一个假定的跨膜片段。乳糖苷酶在乳酸乳球菌中的异源表达和同源表达。Cremoris MG 1363和L.分别对gasseri JCM 1131（T）进行了研究。表达GaaI的菌株对gassericin A的抗性比相应的对照菌株高至少7倍，表明GaaI编码gassericin A的免疫肽。比较Gastrointestinal的肽与发现在循环细菌素基因位点的相似特征进行了讨论。
Gassericin A, produced by Lactobacillus gasseri LA39, is a hydrophobic circular bacteriocin. The DNA region surrounding the gassericin A structural gene, gaaA, was sequenced, and seven open reading frames (ORFs) of 3.5 kbp (gaaBCADITE) were found with possible functions in gassericin A production, secretion, and immunity. The deduced products of the five consecutive ORFs gaaADITE have homology to those of genes involved in butyrivibriocin AR10 production, although the genetic arrangements are different in the two circular bacteriocin genes. GaaI is a small, positively charged hydrophobic peptide of 53 amino acids containing a putative transmembrane segment. Heterologous expression and homologous expression of GaaI in Lactococcus lactis subsp. cremoris MG1363 and L. gasseri JCM1131(T), respectively, were studied. GaaI-expressing strains exhibited at least sevenfold-higher resistance to gassericin A than corresponding control strains, indicating that gaaI encodes an immunity peptide for gassericin A. Comparison of GaaI to peptides with similar characteristics found in the circular bacteriocin gene loci is discussed.