Schaefer Laura, Uicker William C, Wicker-Planquart Catherine, Foucher Anne-Emmanuelle, Jault Jean-Michel, Britton Robert A
Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, Michigan 48824, USA.
J Bacteriol. 2006 Dec;188(23):8252-8. doi: 10.1128/JB.01213-06. Epub 2006 Sep 22.
GTPases have been demonstrated to be necessary for the proper assembly of the ribosome in bacteria and eukaryotes. Here, we show that the essential GTPases YphC and YsxC are required for large ribosomal subunit biogenesis in Bacillus subtilis. Sucrose density gradient centrifugation of large ribosomal subunits isolated from YphC-depleted cells and YsxC-depleted cells indicates that they are similar to the 45S intermediate previously identified in RbgA-depleted cells. The sedimentation of the large-subunit intermediate isolated from YphC-depleted cells was identical to the intermediate found in RbgA-depleted cells, while the intermediate isolated from YsxC-depleted cells sedimented slightly slower than 45S, suggesting that it is a novel intermediate. Analysis of the protein composition of the large-subunit intermediates isolated from either YphC-depleted cells or YsxC-depleted cells indicated that L16 and L36 are missing. Purified YphC and YsxC are able to interact with the ribosome in vitro, supporting a direct role for these two proteins in the assembly of the 50S subunit. Our results indicate that, as has been demonstrated for Saccharomyces cerevisiae ribosome biogenesis, bacterial 50S ribosome assembly requires the function of multiple essential GTPases.
已证明GTP酶对于细菌和真核生物中核糖体的正确组装是必需的。在此，我们表明必需的GTP酶YphC和YsxC是枯草芽孢杆菌中大核糖体亚基生物合成所必需的。对从YphC缺失细胞和YsxC缺失细胞中分离出的大核糖体亚基进行蔗糖密度梯度离心表明，它们类似于先前在RbgA缺失细胞中鉴定出的45S中间体。从YphC缺失细胞中分离出的大亚基中间体的沉降与在RbgA缺失细胞中发现的中间体相同，而从YsxC缺失细胞中分离出的中间体沉降速度略慢于45S，表明它是一种新的中间体。对从YphC缺失细胞或YsxC缺失细胞中分离出的大亚基中间体的蛋白质组成分析表明，L16和L36缺失。纯化的YphC和YsxC能够在体外与核糖体相互作用，支持这两种蛋白质在50S亚基组装中发挥直接作用。我们的结果表明，正如酿酒酵母核糖体生物合成所证明的那样，细菌50S核糖体组装需要多种必需GTP酶的功能。
