Induction of β-Lactamase Influences the Course of Development in Myxococcus xanthus

Abstract

Myxococcus xanthus is a gram-negative bacterium that develops in response to starvation on a solid surface. The cells assemble into multicellular aggregates in which they differentiate from rod-shaped cells into spherical, environmentally resistant spores. Previously, we have shown that the induction of β-lactamase is associated with starvation-independent sporulation in liquid culture (K. A. O’Connor and D. R. Zusman, Mol. Microbiol. 24:839–850, 1997). In this paper, we show that the chromosomally encoded β-lactamase of M. xanthus is autogenously induced during development. The specific activity of the enzyme begins to increase during aggregation, before spores are detectable. The addition of inducers of β-lactamase in M. xanthus, such as ampicillin, d-cycloserine, and phosphomycin, accelerates the onset of aggregation and sporulation in developing populations of cells. In addition, the exogenous induction of β-lactamase allowsM. xanthus to fruit on media containing concentrations of nutrients that are normally too high to support development. We propose that the induction of β-lactamase is an integral step in the development of M. xanthus and that this induction is likely to play a role in aggregation and in the restructuring of peptidoglycan which occurs during the differentiation of spores. In support of this hypothesis, we show that exogenous induction of β-lactamase can rescue aggregation and sporulation of certain mutants. Fruiting body spores from a rescued mutant are indistinguishable from wild-type fruiting body spores when examined by transmission electron microscopy. These results show that the signal transduction pathway leading to the induction of β-lactamase plays an important role in aggregation and sporulation in M. xanthus.

Deciphering the hunting strategy of a bacterial wolfpack

“…Like most bacteria, M. xanthus is facultatively multicellular. Individual cell traits include the ability to grow and divide in asocial contexts, ‘adventurous’ gliding motility of isolated cells (A‐motility) and rapid sporulation in the presence of cell wall disrupting agents in dispersed liquid culture (Dworkin, 1962; MacNeil et al , 1994; O'Connor & Zusman, 1999). However, M. xanthus individualism is tempered with group behaviors.…”

An ambruticin-sensing complex modulates Myxococcus xanthus development and mediates myxobacterial interspecies communication

“…As indicated by previous work, the chemically induced sporulation might also be considered as an “emergency program” of vegetative cells faced with adverse conditions although the presence of nutrients would support vegetative growth. This is indicated by work of O’Connor and Zusman, which shows that agents causing damage to the peptidoglycan induce sporulation 12 , 38 . The presence of glycerol in high amounts mimics another adverse condition well-known as hyperosmotic stress.…”

CrdA regulates endogenous beta-lactamase activity in Myxococcus xanthus

“…Non-specific Induction of Beta-lactamase Both starvation-dependent and independent sporulation are accompanied by the induction of beta-lactamases (O'Connor, 1997, O'Connor, 1999. The crdA mutant is not able to induce beta-lactamases when grown with ampicillin, and it has a defect in ampicillin-induced sporulation.…”