Morales Angeles Danae, Liu Yun, Hartman Alwin M, Borisova Marina, de Sousa Borges Anabela, de Kok Niels, Beilharz Katrin, Veening Jan-Willem, Mayer Christoph, Hirsch Anna K H, Scheffers Dirk-Jan
Department of Molecular Microbiology, Groningen Biomolecular Sciences and Biotechnology Institute University of Groningen, The Netherlands.
Stratingh Institute for Chemistry, University of Groningen, The Netherlands.
Mol Microbiol. 2017 Apr;104(2):319-333. doi: 10.1111/mmi.13629. Epub 2017 Feb 6.
Peptidoglycan (PG), the major component of the bacterial cell wall, is one large macromolecule. To allow for the different curvatures of PG at cell poles and division sites, there must be local differences in PG architecture and eventually also chemistry. Here we report such local differences in the Gram-positive rod-shaped model organism Bacillus subtilis. Single-cell analysis after antibiotic treatment and labeling of the cell wall with a fluorescent analogue of vancomycin or the fluorescent D-amino acid analogue (FDAA) HCC-amino-D-alanine revealed that PG at the septum contains muropeptides with unprocessed stem peptides (pentapeptides). Whereas these pentapeptides are normally shortened after incorporation into PG, this activity is reduced at division sites indicating either a lower local degree of PG crosslinking or a difference in PG composition, which could be a topological marker for other proteins. The pentapeptides remain partially unprocessed after division when they form the new pole of a cell. The accumulation of unprocessed PG at the division site is not caused by the activity of the cell division specific penicillin-binding protein 2B. To our knowledge, this is the first indication of local differences in the chemical composition of PG in Gram-positive bacteria.
肽聚糖（PG）是细菌细胞壁的主要成分，是一种大分子。为了适应细胞两极和分裂位点处PG的不同曲率，PG的结构最终在化学性质上必然存在局部差异。在此，我们报道了革兰氏阳性杆状模式生物枯草芽孢杆菌中存在这样的局部差异。用万古霉素的荧光类似物或荧光D - 氨基酸类似物（FDAA）HCC - 氨基 - D - 丙氨酸对细胞壁进行标记并经抗生素处理后的单细胞分析表明，隔膜处的PG含有带有未加工茎肽（五肽）的胞壁肽。虽然这些五肽在掺入PG后通常会缩短，但在分裂位点处这种活性降低，这表明要么是PG交联的局部程度较低，要么是PG组成存在差异，而这可能是其他蛋白质的拓扑标记。当五肽形成细胞的新极时，它们在分裂后仍部分未加工。分裂位点处未加工PG的积累不是由细胞分裂特异性青霉素结合蛋白2B的活性引起的。据我们所知，这是革兰氏阳性细菌中PG化学成分存在局部差异的首个迹象。
