Kawai Yoshikazu, Mercier Romain, Errington Jeff
Centre for Bacterial Cell Biology, Institute for Cell and Molecular Biosciences, Medical School, Newcastle University, Richardson Road, Newcastle upon Tyne NE2 4AX, UK.
Centre for Bacterial Cell Biology, Institute for Cell and Molecular Biosciences, Medical School, Newcastle University, Richardson Road, Newcastle upon Tyne NE2 4AX, UK.
Curr Biol. 2014 Apr 14;24(8):863-7. doi: 10.1016/j.cub.2014.02.053. Epub 2014 Apr 3.
Morphogenesis, the development of shape or form in cells or organisms, is a fundamental but poorly understood process throughout biology. In the bacterial domain, cells have a wide range of characteristic shapes, including rods, cocci, and spirals. The cell wall, composed of a simple meshwork of long glycan strands crosslinked by short peptides (peptidoglycan, PG) and anionic cell wall polymers such as wall teichoic acids (WTAs), is the major determinant of cell shape. It has long been debated whether the formation of new wall material or the transmission of shape from parent to daughter cells requires existing wall material as a template. However, rigorous testing of this hypothesis has been problematical because the cell wall is normally an essential structure. L-forms are wall-deficient variants of common bacteria that have been classically identified as antibiotic-resistant variants in association with a wide range of infectious diseases. We recently determined the genetic basis for the L-form transition in the rod-shaped bacterium Bacillus subtilis and thus how to generate L-forms reliably and reproducibly. Using the new L-form system, we show here that we can delete essential genes for cell wall synthesis and propagate cells in the long-term absence of a cell wall template molecule. Following genetic restoration of cell wall synthesis, we show that the ability to generate a classical rod-shaped cell is restored, conclusively rejecting template-directed models, at least for the establishment of cell shape in B. subtilis.
形态发生，即细胞或生物体形状或形态的发育，是整个生物学领域一个基本但却知之甚少的过程。在细菌领域，细胞具有多种特征形状，包括杆状、球状和螺旋状。细胞壁由长聚糖链通过短肽交联而成的简单网络（肽聚糖，PG）以及阴离子细胞壁聚合物（如壁磷壁酸，WTAs）组成，是细胞形状的主要决定因素。新壁物质的形成或形状从亲代细胞传递到子代细胞是否需要现有壁物质作为模板，长期以来一直存在争议。然而，对这一假设进行严格测试一直存在问题，因为细胞壁通常是一种必不可少的结构。L型细菌是常见细菌的无壁变体，传统上被认定为与多种传染病相关的抗生素抗性变体。我们最近确定了杆状细菌枯草芽孢杆菌L型转变的遗传基础，从而知道如何可靠且可重复地产生L型细菌。利用新的L型细菌系统，我们在此表明，我们可以删除细胞壁合成的必需基因，并在长期缺乏细胞壁模板分子的情况下培养细胞。在细胞壁合成进行基因修复后，我们表明产生经典杆状细胞的能力得以恢复，这最终否定了模板导向模型，至少对于枯草芽孢杆菌细胞形状的建立来说是这样。
