Maezawa Kazuki, Shigenobu Shuji, Taniguchi Hisaaki, Kubo Takeo, Aizawa Shin-Ichi, Morioka Mizue
Prefectural University of Hiroshima, Department of Life Sciences, 562 Nanatsuka, Shobara, Hiroshima 727-0023, Japan.
J Bacteriol. 2006 Sep;188(18):6539-43. doi: 10.1128/JB.00561-06.
Buchnera aphidicola is the endosymbiotic bacterium of the pea aphid. Due to its small genome size, Buchnera lacks many essential genes for autogenous life but obtains nutrients from the host. Although the Buchnera cell is nonmotile, it retains clusters of flagellar genes that lack the late genes necessary for motility, including the flagellin gene. In this study, we show that the flagellar genes are actually transcribed and translated and that the Buchnera cell surface is covered with hundreds of hook-basal-body (HBB) complexes. The abundance of HBB complexes suggests a role other than motility. We discuss the possibility that the HBB complex may serve as a protein transporter not only for the flagellar proteins but also for other proteins to maintain the symbiotic system.
蚜虫内共生菌是豌豆蚜虫的内共生细菌。由于其基因组规模较小，蚜虫内共生菌缺乏许多自主生存所必需的基因，但能从宿主获取营养。尽管蚜虫内共生菌细胞不能运动，但它保留了鞭毛基因簇，这些基因簇缺少运动所需的晚期基因，包括鞭毛蛋白基因。在本研究中，我们表明鞭毛基因实际上是转录和翻译的，并且蚜虫内共生菌细胞表面覆盖着数百个钩-基体（HBB）复合体。HBB复合体的丰富性表明其具有除运动之外的其他作用。我们讨论了HBB复合体不仅可以作为鞭毛蛋白的蛋白质转运体，还可以作为其他蛋白质的转运体来维持共生系统的可能性。
