Proteome profiling of Campylobacter jejuni 81-176 at 37°C and 42°C by label-free mass spectrometry

Abstract Background The main natural reservoir for Campylobacter jejuni is the intestinal tract of birds, especially in the context of human nutrition chickens and turkeys play the main role. There, C. jejuni multiplies optimally at 42°C, the avian body temperature, while after infection of humans by peroral intake in the human intestinal tract only 37°C prevail. Proteome profiling by label-free mass spectrometry (DIA-MS) was performed to examine the processes which enable C. jejuni strain 81-176 to adapt to 37°C in comparison to 42°C. In total, four states were compared with each other: incubation for 12 h at 37°C, for 24 h at 37°C, for 12 h at 42°C and 24 h at 42°C. Results It was shown that the proteome profile changes not only according to the different incubation temperature but also with the length of the incubation period, i.e. significant differences in protein expression were evident when comparing 37°C and 42°C as well as 12 h and 24 h of incubation. Altogether, the expression of 957 proteins was quantifiable. Out of these, 37.1% - 47.3% were considered to be significantly differentially expressed, that means these proteins showed at least a 1.5-fold change in either direction (i.e log 2 FC ≥ 0.585 or log 2 FC ≤ -0.585) and an FDR-adjusted p-value of less than 0.05. The significantly differentially expressed proteins could be arranged in 4 different clusters and 16 functional catogories. Conclusions The C. jejuni proteome at 42°C is better adopted to high replication rates than that at 37°C, which was in particular indicated by the up-expression of proteins belonging to the functional categories "replication", "DNA synthesis and repair factors", "lipid and carbohydrate biosynthesis" and "vitamin synthesis, metabolism, cofactor biosynthesis". The relative up-expression of proteins with chaperone function at 37°C in comparison to 42°C after 12 h incubation indicates a temporary lower-temperature adaptation response. Additionally the up-expression of factors for DNA uptake at 37°C compared to 42°C indicate a higher competence for the acquisition of extraneous DNA at human body temperature.