Exopolysaccharide biosynthesis genes required for social motility in Myxococcus xanthus
Exopolysaccharide biosynthesis genes required for social motility in Myxococcus xanthus
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DOI：
10.1111/j.1365-2958.2004.04369.x
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发表时间：
2005-01-01
影响因子：
3.6
通讯作者：
Shi, WY
中科院分区：
文献类型：
--
作者：
Lu, A;Cho, KY;Shi, WY
黄色粘球菌的社会（S）运动是一种不依赖鞭毛的滑行运动系统，允许细菌在固体表面上成群运动。已经证明S运动需要IV型皮利（TFP）、胞外多糖（EPS;原纤维的组分）和脂多糖（LPS）。以前，关于M.缺少Xanthus。在这项研究中，我们筛选了5000个随机诱变菌落的缺陷，S-运动和EPS，并确定了两个遗传区域的EPS生物合成所必需的：EPS合成（EPS）区域和EPS相关（EAS）区域。在eps和eas区域插入的突变体在S-运动和子实体形成方面有缺陷。这些突变体不能结合荧光钙白色染料，表明它们缺乏EPS;然而，它们保留了正常的TFP和LPS。eps基因座的分析显示了几个开放阅读框（ORF），编码同源糖基转移酶，葡聚糖酶和EPS转运蛋白以及调节蛋白; eas基因座包含两个ORF：一个表现出同源性与未知功能的保守结构域的假设蛋白质和其他显示没有明显的同源性，在数据库中的其他蛋白质。进一步的遗传突变分析表明，整个eps区域参与原纤维和原纤维EPS的生物合成。通过产生框内缺失突变来分析eps区近端的操纵子。这些突变体在细菌产生EPS或执行EPS相关功能的能力上表现出不同程度的缺陷，证实了这些基因参与了M。苍耳EPS生物发生
Social (S)-motility in Myxococcus xanthus is a flagellum-independent gliding motility system that allows bacteria to move in groups on solid surfaces. S-motility has been shown to require type IV pili (TFP), exopolysaccharide (EPS; a component of fibrils) and lipopolysaccharide (LPS). Previously, information concerning EPS biogenesis in M. xanthus was lacking. In this study, we screened 5000 randomly mutagenized colonies for defects in S-motility and EPS and identified two genetic regions essential for EPS biogenesis: the EPS synthesis (eps) region and the EPS-associated (eas) region. Mutants with insertions in the eps and eas regions were defective in S-motility and fruiting body formation. These mutants failed to bind the dye calcofluor white, indicating that they lacked EPS; however, they retained normal TFP and LPS. Analysis of the eps locus showed several open reading frames (ORFs) that encode homologues to glycosyltransferases, glucanases and EPS transporters as well as regulatory proteins; the eas locus contains two ORFs: one exhibits homology to hypothetical proteins with a conserved domain of unknown function and the other displays no apparent homology to other proteins in the database. Further genetic mutagenesis analysis indicates that the whole eps region is involved in the biosynthesis of fibrils and fibril EPS. The operon at the proximal end of the eps region was analysed by generating in-frame deletion mutations. These mutants showed varying degrees of defects in the bacterium's ability to produce EPS or perform EPS-related functions, confirming the involvement of these genes in M. xanthus EPS biogenesis.