Natural Transformation of Myxococcus xanthus
Natural Transformation of Myxococcus xanthus
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DOI：
10.1128/jb.00041-11
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发表时间：
2011-03
影响因子：
3.2
通讯作者：
Jing Wang;Wei Hu;R. Lux;Xuesong He;Yue-zhong Li;W. Shi
中科院分区：
文献类型：
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作者：
Jing Wang;Wei Hu;R. Lux;Xuesong He;Yue-zhong Li;W. Shi
黄粘球菌（Myxococcus xanthus）属于变形杆菌的三角洲纲，以其复杂的生活方式、社会行为和相对较大的基因组而闻名。虽然先前的观察表明黄原草存在水平基因转移，但其通过自然转化吸收外源DNA的能力尚未得到实验证明。在这项研究中，我们利用自主复制的黏菌质粒pZJY41作为供体DNA，在M. xanthus中实现了自然转化。黄原胞外多糖（EPS）被证明是转化的胞外屏障。缺乏EPS的细胞，例如携带ΔdifA或ΔepsA的突变株，可以自然转化。在转化的内部障碍中，有限制修饰系统，可以在转化前利用黄原菌的细胞提取物在体外甲基化DNA来克服部分障碍。此外，DNA与细胞的孵育时间和二价镁离子的存在也影响黄原菌的转化频率。此外，我们还观察到IV型菌毛系统在黄原草DNA摄取机制中的潜在参与。在ΔpilQ/epsA和Δtgl/epsA突变体中完全消除了自然转化，而在ΔepsA背景下pilB或pilC的零突变降低了转化率。据我们所知，我们的研究提供了三角洲变形菌中自然可转化物种的第一个例子。
ABSTRACT Myxococcus xanthus belongs to the delta class of the proteobacteria and is notable for its complex life-style with social behaviors and relatively large genome. Although previous observations have suggested the existence of horizontal gene transfer in M. xanthus, its ability to take up exogenous DNA via natural transformation has not been experimentally demonstrated. In this study, we achieved natural transformation in M. xanthus using the autonomously replicating myxobacterial plasmid pZJY41 as donor DNA. M. xanthus exopolysaccharide (EPS) was shown to be an extracellular barrier for transformation. Cells deficient in EPS production, e.g., mutant strains carrying ΔdifA or ΔepsA, became naturally transformable. Among the inner barriers to transformation were restriction-modification systems in M. xanthus, which could be partially overcome by methylating DNA in vitro using cell extracts of M. xanthus prior to transformation. In addition, the incubation time of DNA with cells and the presence of divalent magnesium ion affected transformation frequency of M. xanthus. Furthermore, we also observed a potential involvement of the type IV pilus system in the DNA uptake machinery of M. xanthus. The natural transformation was totally eliminated in the ΔpilQ/epsA and Δtgl/epsA mutants, and null mutation of pilB or pilC in an ΔepsA background diminished the transformation rate. Our study, to the best of our knowledge, provides the first example of a naturally transformable species among deltaproteobacteria.