Identification of the cglC, cglD, cglE, and cglF Genes and Their Role in Cell Contact-Dependent Gliding Motility in Myxococcus xanthus
Identification of the cglC, cglD, cglE, and cglF Genes and Their Role in Cell Contact-Dependent Gliding Motility in Myxococcus xanthus
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DOI：
10.1128/jb.00055-12
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发表时间：
2012-04-01
影响因子：
3.2
通讯作者：
Wall, Daniel
中科院分区：
文献类型：
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作者：
Pathak, Darshankumar T.;Wall, Daniel
在黄色粘球菌生物膜内，细胞主动移动并交换其外膜 (OM) 脂蛋白和脂质。在遗传上不同的菌株之间，OM 交换可以调节受体细胞的行为，包括滑动运动和发育。尽管许多不同的蛋白质被认为会发生交换，但迄今为止，仅已知两种内源性 OM 脂蛋白 CglB 和 Tgl 会被转移。蛋白质交换需要受体细胞和供体细胞中的 TraAB 蛋白，假设它们可以促进 OM 融合以进行转移。为了更好地了解交换的蛋白质类型，我们鉴定了其余一组 cgl 滑动运动突变体的基因。这些突变体是独特的，因为它们的运动缺陷可以通过与编码相应野生型蛋白的供体细胞的物理接触而暂时恢复，这一过程称为刺激。与CglB和Tgl类似，cglC和cglD基因编码II型信号序列，表明它们也是脂蛋白。令人惊讶的是，cglE 和 cglF 基因反而编码 I 型信号序列，这表明非脂蛋白也发生了交换。与这个想法一致，向 cglF 突变体中添加外源合成 CglF 蛋白（71 个氨基酸）可以挽救其运动缺陷。与活体供体细胞相反，纯化的CglF蛋白的刺激独立于TraA发生。这些结果还表明CglF可能定位于细胞表面。讨论了我们的研究结果对 OM 交换的影响。
Within Myxococcus xanthus biofilms, cells actively move and exchange their outer membrane (OM) lipoproteins and lipids. Between genetically distinct strains, OM exchange can regulate recipient cell behaviors, including gliding motility and development. Although many different proteins are thought to be exchanged, to date, only two endogenous OM lipoproteins, CglB and Tgl, are known to be transferred. Protein exchange requires the TraAB proteins in recipient and donor cells, where they are hypothesized to facilitate OM fusion for transfer. To better understand the types of proteins exchanged, we identified the genes for the remaining set of cgl gliding motility mutants. These mutants are unique because their motility defect can be transiently restored by physical contact with donor cells that encode the corresponding wild-type protein, a process called stimulation. Similar to CglB and Tgl, the cglC and cglD genes encode type II signal sequences, suggesting that they are also lipoproteins. Surprisingly, the cglE and cglF genes instead encode type I signal sequences, suggesting that nonlipoproteins are also exchanged. Consistent with this idea, the addition of exogenous synthetic CglF protein (71 amino acids) to a cglF mutant rescued its motility defect. In contrast to a live donor cell, stimulation with purified CglF protein occurred independently of TraA. These results also indicate that CglF may localize to the cell surface. The implications of our findings on OM exchange are discussed.