Quantitative proteomics reveals oxygen-induced adaptations in Caldalkalibacillus thermarum TA2.A1 chemostat cultures

ABSTRACT: Caldalkalibacillus thermarum possesses a highly branched respiratory chain. Branched electron transport chains (ETC) in model organisms such as Escherichia coli primarily facilitate growth at a wide range of dissolved oxygen levels. The aim of this study was to investigate whether a polyextremophile such as C. thermarum is regulated in a similar fashion. With this in mind, the organism was cultivated in chemostat bioreactors with a range of oxygen levels in the inlet gas (0.25% O2 – 4.2% O2). Proteomic analysis unexpectedly showed both the type I and the type II NADH dehydrogenases present in all conditions. Moreover, also two different terminal oxidases were present. The cytochrome c:oxygen aa3 complex abundance was highest at 4.2% O2, while the cytochrome c:oxygen ba3 complex exhibited higher abundance at the lowest O2 concentration 0.25% O2. The abundance of the cytochrome c:oxygen ba3 complex started to decline below 0.42% O2. Often this would result in emergence of the cytochrome c:oxygen bb3 complex or the menaquinol:oxygen bd complex, the other two terminal oxidases of C. thermarum; but neither was detected. Besides changes in the respiratory chain, the sodium-proton antiporter complex Mrp was downregulated under the lower oxygen levels. Normally, in alkaliphiles, this enzyme is considered crucial for sodium homeostasis. We propose that the existence of a sodium:acetate exporter decreases the requirement for Mrp under strong oxygen limitation, introducing a novel perspective to the field of alkaliphiles. contact: [e-mail] or [e-mail]

INSTRUMENT(S): Q Exactive HF

ORGANISM(S): Caldalkalibacillus Thermarum Ta2.a1

SUBMITTER: Martin Pabst  

LAB HEAD: Martin Pabst

PROVIDER: PXD047466 | Pride | 2025-01-18

REPOSITORIES: Pride