Outer membrane proteome and its regulation networks in response to glucose concentration changes in Escherichia coli

Abstract

Escherichia coli growth is a complicated process involved in many factors including the utilization of glucose. It has been reported that E. coli cell growth rate is closely related with glucose concentrations in the cell culture medium. However, the protein regulation networks in response to glucose concentration changes are largely unknown. In the present study, a sub-proteomic methodology has been utilized to characterize alterations of E. coli OM proteins in response to 0.02, 0.2 and 2% concentrations of glucose. In comparison with E. coli cells treated with 0.2% glucose concentration, downregulation of FhuE, FepA, CirA, TolC and OmpX and upregulation of LamB, FadL, OmpF, OmpT and Dps were detected in the E. coli cells treated with 0.02% glucose, and a decrease of TolC, LamB, OmpF, OmpT, OmpX, Dps and elevation of FhuE, FepA, CirA, YncD, FadL and MipA were found in 2% glucose. TolC, LamB and OmpT showed more important roles than other altered OM proteins. Furthermore, the interaction among these altered OM proteins was investigated, and protein interaction networks were characterized. In the networks, all proteins were interacted and regulated by others. TolC, LamB and Dps were the top three proteins that regulated more proteins than others, whereas CirA and OmpT were the top two proteins that were regulated by others. The protein networks could be modified correspondingly with the changes of glucose concentrations. The modifications included the addition of new OM proteins or the change of regulation direction. These findings suggest the important roles of the bacterial OM protein network in E. coli's responses to glucose concentration changes and other environment stresses.

Improvement of n-butanol tolerance in Escherichia coliby membrane-targeted tilapia metallothionein

“…It was also observed that the growth rate of the TMT strain in M9 medium was 1.65 times lower when compared to the rate observed in PYG medium cultured TMT strain. Previous reports have observed that the porins OmpF and OmpC are differentially regulated by glucose concentrations because the two porins constitute the main glucose entry channels into the periplasm when the carbon source is present at a higher concentration of 0.2 mM (0.036 g/l) [38]. Cellular growth rate has been correlated to the uptake of glucose via OmpF and OmpC.…”

Altered Outer Membrane Transcriptome Balance with AmpC Overexpression in Carbapenem-Resistant Enterobacter cloacae

“…Various regulatory cascades can be launched in response to changing environmental conditions. Among possible mechanisms involved in decreasing OM permeability due to OmpC-directed OM porin balance, we can mention the increased expression of bolA morphogene responsible for adaptive stress response in Enterobacteriaceae (Freire et al, 2006), and the TolC, LamB, and Dps proteins which can significantly influence OM protein network (Yang et al, 2011). Handling of the OM protein balance according to environmental factors may also be conditioned by the two-component regulatory system OmpR-EnvZ (Chhabra et al, 2012; Shimada et al, 2015).…”

“…Moreover, the authors proved that mutations within histidine kinase CpxA showed the possible fixation of OmpC-directed OM polarization. It can be assumed that factors disturbing the physiological regulatory cascade may be associated with consistent OM protein balance polarization toward OmpC with restrictive channel or abnormal expression of both major porins (Malickbasha et al, 2010; Yang et al, 2011; Tängdén et al, 2013). …”

Bioinformatic study of the relationship between protein regulation and sequence properties

“…The investigation of the correlation between the protein regulation, amino acid composition and codon usage pattern may thus help us to better understand the cell regulatory mechanisms and in many cases how protein regulation is involved in the (often poorly understood) protein networks [21]. However, an efficient bioinformatic method to systematically explore such relationships in the context of high-throughput proteomics has not yet been developed.…”