Proteomic analysis of the copper resistance of Streptococcus pneumoniae

Abstract

Streptococcus pneumoniae is a Gram-positive bacterial pathogen causing a variety of diseases, including otitis media, bacteraemia and meningitis. Although copper is an essential trace metal for bacterial growth, high intracellular levels of free-copper are toxic. Copper resistance has emerged as an important virulence determinant of microbial pathogens. In this study, we determined the minimum inhibition concentration of copper for the growth inhibition of S. pneumoniae. Two-dimensional-electrophoresis coupled with mass spectrometry was applied to identify proteins involved in copper resistance of S. pneumoniae. In total, forty-four proteins with more than 1.5-fold alteration in expression (p < 0.05) were identified. Quantitative reverse transcription PCR was used to confirm the proteomic results. Bioinformatics analysis showed that the differentially expressed proteins were mainly involved in the cell wall biosynthesis, protein biosynthesis, purine biosynthesis, pyrimidine biosynthesis, primary metabolic process, and the nitrogen compound metabolic process. Many up-regulated proteins in response to the copper treatment directly or indirectly participated in the cell wall biosynthesis, indicating that the cell wall is a critical determinant in copper resistance of S. pneumoniae.

Identification of key proteins and pathways in cadmium tolerance of Lactobacillus plantarum strains by proteomic analysis

“…As shown in Fig. 1, the dose of Cd at 5 mg/L (1/2 MIC value of the Cd-sensitive strain CCFM191) was selected for modeling a moderate and sublethal Cd exposure in the following experiments based on the previous related study 33, 34 .…”

“…As it is normally to incubate the bacteria in liquid medium for proteomic analysis 33, 61 , twenty L . plantarum strains were inoculated (2% v/v) into MRS broth containing Cd 2+ ranging from 0 mg/L to 50 mg/L and then incubated at 37 °C.…”

“…The OD 600 values were measured at different time points until the stationary phase of the strains. The relative growth rate of each strain was expressed as a percentage of that of the control culture (without Cd exposure) which was assigned a value of 100% 33, 61 . The MIC value of each strain was determined as the lowest Cd concentration that completely inhibited the growth rate of the strains.…”

“…The strains were grown in the Cd containing MRS broth at 37 °C and the Cd concentration was set as the 1/2 MIC value of the sensitive strain (5 mg/L) as that was established previously 33, 34 . The strains were also incubated in Cd-free media as a control.…”

Caracterização da comunidade bacteriana de uma área de processamento de cobre e estudo do mecanismo de resistência a este metal.

“…O STRING é uma ferramenta que vêm sendo muito utilizada (CRESTANI, 2011;GUO et al, 2015;ZOU et al, 2015), pois se conecta a vários outros bancos de dados permitindo a visualização da interação direta entre as proteínas e associações funcionais (interação proteína-proteína, vias biológicas e funções moleculares).…”