Myxococcus xanthus as a Model Organism for Peptidoglycan Assembly and Bacterial Morphogenesis

Abstract

A fundamental question in biology is how cell shapes are genetically encoded and enzymatically generated. Prevalent shapes among walled bacteria include spheres and rods. These shapes are chiefly determined by the peptidoglycan (PG) cell wall. Bacterial division results in two daughter cells, whose shapes are predetermined by the mother. This makes it difficult to explore the origin of cell shapes in healthy bacteria. In this review, we argue that the Gram-negative bacterium Myxococcus xanthus is an ideal model for understanding PG assembly and bacterial morphogenesis, because it forms rods and spheres at different life stages. Rod-shaped vegetative cells of M. xanthus can thoroughly degrade their PG and form spherical spores. As these spores germinate, cells rebuild their PG and reestablish rod shape without preexisting templates. Such a unique sphere-to-rod transition provides a rare opportunity to visualize de novo PG assembly and rod-like morphogenesis in a well-established model organism.

Coordinated peptidoglycan synthases and hydrolases stabilize the bacterial cell wall

“…When spores germinate, emerging cells rebuild rod-shaped PG without preexisting templates 23 . Such morphological transitions make M. xanthus an ideal organism to study PG degradation and assembly 24 . The Rod system is essential for the de novo establishment of rod shape during M. xanthus spore germination 23 , 25 .…”

Suppression of predominant interfering bacteria in the purification process of myxobacteria

“…According to a previous report on the purification of myxospores by heat treatment ( 17 ), it was shown that myxospores in distilled water often resist the heat treatment up to 58°C, while the majority of the contaminant does not. The intensity of frequency and duration of the exposure as the cardinal factors in the elimination of contamination and maintenance of myxospores, were determined for the myxospore of four myxobacterial genera in the current study.…”

“…Since myxospores do not germinate in nutrient-rich media in presence of fast growing heterotrophic bacteria, they can tolerate to the exposure of the toxicants such as antibiotics. The contaminants can be suppressed by the inhibitors of cell fission and the fruiting bodies are transferred into a suitable growth medium on which their myxospores can germinate without being affected by the fast growing contaminant cells ( 17 ).…”

“…Since myxospores do not germinate in nutrient-rich media in presence of fast growing heterotrophic bacteria, they can tolerate to the exposure of the toxicants such as antibiotics. The contaminants can be suppressed by the inhibitors of cell fission and the fruiting bodies are transferred into a suitable growth medium on which their myxospores can germinate without being affected by the fast growing VY/2 agar (Baker's yeast 5 g/L, CaCl 2H O 1 g/L, contaminant cells (17). agar15 g/L, Vitamin B 0.0005g/L) and CY medium Contaminated fruiting bodies were then trans-(Casitone 3 g/L, yeast extract 1 g/L, CaCl 2H O 1 ferred by a sterile needle to WAT agar plates containg/L, and agar 15 g/L) and were incubated at 28ºC for 3-10days (16).…”

The coordination between penicillin-binding protein 1a (PBP1a) and the hydrolytic peptidase DacB determines the integrity of bacterial cell poles

“…In response to chemical signals, such as glycerol, vegetative cells of M. xanthus thoroughly degrade their PG and transform into spherical spores within two to four hours despite that the expression of the dacB gene is not regulated 20,[27][28][29][30] . If DacB also degrades PG during sporulation, glycerol-induced sporulation could provide a scenario where DacB is highly activated.…”