Investigating the role of the multicomponent signaling system NmpRSTU in oxygen-dependent phenotypes of Myxococcus xanthus

Abstract

Myxococcus xanthus is an aerobic soil bacterium with complex social behaviors regulated by numerous two-component systems (TCSs). These TCSs sense and respond to environmental and cellular conditions. The Bretl lab has characterized a multi-component TCS named NmpRSTU, which senses oxygen and regulates genes related to oxygen utilization. Despite requiring oxygen to produce energy, M. xanthus must encounter soil environments with reduced oxygen levels. However, most research of this bacterium has been done under ambient oxygen. Therefore, little is understood about M. xanthus behaviors in low-oxygen conditions and the role of NmpRSTU is undefined. The first aim of my project was to characterize phenotypes of M. xanthus in low oxygen, specifically: growth, survival, motility, and development. M. xanthus growth was delayed during low aeration, although it could survive longer than anticipated with reduced available oxygen. Furthermore, M. xanthus moved and developed at lower oxygen concentrations than expected. I also found that NmpRSTU affected M. xanthus growth, cell morphology, and development during low oxygen exposure. Finally, my second aim focused on the importance of the cbb3 oxidase in the low oxygen response. It was determined that the cbb3 oxidase may be essential for M. xanthus growth as it could not be deleted.