Taschner P E, Huls P G, Pas E, Woldringh C L
Department of Electron Microscopy and Molecular Cytology, University of Amsterdam, The Netherlands.
J Bacteriol. 1988 Apr;170(4):1533-40. doi: 10.1128/jb.170.4.1533-1540.1988.
Isogenic ftsZ, ftsQ, ftsA, pbpB, and ftsE cell division mutants of Escherichia coli were compared with their parent strain in temperature shift experiments. To improve detection of phenotypic differences in division behavior and cell shape, the strains were grown in glucose-minimal medium with a decreased osmolality (about 100 mosM). Already at the premissive temperature, all mutants, particularly the pbpB and ftsQ mutants, showed an increased average cell length and cell mass. The pbpB and ftsQ mutants also exhibited a prolonged duration of the constriction period. All strains, except ftsZ, continued to initiate new constrictions at 42 degrees C, suggesting the involvement of FtsZ in an early step of the constriction process. The new constrictions were blunt in ftsQ and more pronounced in ftsA and pbpB filaments, which also had elongated median constrictions. Whereas the latter strains showed a slow recovery of cell division after a shift back to the permissive temperature, ftsZ and ftsQ filaments recovered quickly. Recovery of filaments occurred in all strains by the separation of newborn cells with an average length of two times LO, the length of newborn cells at the permissive temperature. The increased size of the newborn cells could indicate that the cell division machinery recovers too slowly to create normal-sized cells. Our results indicate a phenotypic resemblance between ftsA and pbpB mutants and suggest that the cell division gene products function in the order FtsZ-FtsQ-FtsA, PBP3. The ftsE mutant continued to constrict and divide at 42 degrees C, forming short filaments, which recovered quickly after a shift back to the permissive temperature. After prolonged growth at 42 degree C, chains of cells, which eventually swelled up, were formed. Although the ftsE mutant produced filaments in broth medium at the restrictive temperature, it cannot be considered a cell division mutant under the presently applied conditions.
在温度转换实验中，将大肠杆菌的同基因ftsZ、ftsQ、ftsA、pbpB和ftsE细胞分裂突变体与其亲本菌株进行了比较。为了更好地检测分裂行为和细胞形状的表型差异，这些菌株在渗透压降低（约100 mosM）的葡萄糖基本培养基中生长。在允许温度下，所有突变体，特别是pbpB和ftsQ突变体，平均细胞长度和细胞质量就已增加。pbpB和ftsQ突变体的缢缩期也延长。除ftsZ外，所有菌株在42℃时继续启动新的缢缩，这表明FtsZ参与了缢缩过程的早期步骤。ftsQ中的新缢缩较钝，而ftsA和pbpB细丝中的新缢缩更明显，其缢缩中部也伸长。尽管后一类菌株在转回允许温度后细胞分裂恢复缓慢，但ftsZ和ftsQ细丝恢复迅速。所有菌株的细丝通过平均长度为允许温度下新生细胞长度LO两倍的新生细胞分离而恢复。新生细胞大小增加可能表明细胞分裂机制恢复过慢，无法产生正常大小的细胞。我们的结果表明ftsA和pbpB突变体之间存在表型相似性，并表明细胞分裂基因产物按FtsZ-FtsQ-FtsA、PBP3的顺序发挥作用。ftsE突变体在42℃时继续缢缩和分裂，形成短细丝，转回允许温度后恢复迅速。在42℃长时间生长后，形成了最终膨胀的细胞链。尽管ftsE突变体在限制性温度下的肉汤培养基中产生细丝，但在目前应用的条件下，它不能被视为细胞分裂突变体。
