Downregulation of Tsx and OmpW and upregulation of OmpX are required for iron homeostasis in Escherichia coli.
Upregulation of outer membrane (OM) proteins was systematically investigated in response to poor iron availability in the host and natural environments, but downregulation of OM proteins was ill-defined in this response. We utilized proteomic methodologies to characterize altered OM proteins in the sarcosine-insoluble fraction of Escherichia coli K12 cultured in LB medium with iron limitation. Notably, three novel proteins, Tsx, OmpW, and OmpX, related to iron homeostasis were identified; Tsx and OmpW were downregulated, and OmpX was upregulated. These alterations were functionally validated with the use of gene overexpression and deletion methods. Of the two downregulated proteins, Tsx was more sensitive to an iron-deficient environment than OmpW. In addition, the significantly negative correlation between Tsx with OmpW was achieved when overexpressed strains were used. These findings strongly indicate that the downregulation of Tsx and OmpW and the upregulation of OmpX are required for iron homeostasis in E. coli.
Lin
Xiang-min
XM
Center for Proteomics, State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou 510275, People's Republic of China.
Wu
Li-na
LN
Li
Hui
H
Wang
San-ying
SY
Peng
Xuan-xian
XX
D001425:Bacterial Outer Membrane Proteins / Q000378:metabolism*; D001483:Base Sequence; D017931:DNA Primers; D015536:Down-Regulation; D015180:Electrophoresis, Gel, Two-Dimensional; D004926:Escherichia coli / Q000378:metabolism*; D029968:Escherichia coli Proteins / Q000378:metabolism*; D006706:Homeostasis; D006867:Hydrolases / Q000378:metabolism*; D007501:Iron / Q000378:metabolism*; D016133:Polymerase Chain Reaction; D040901:Proteomics; D011991:Receptors, Virus / Q000378:metabolism*
D001425:Bacterial Outer Membrane Proteins; D017931:DNA Primers; D029968:Escherichia coli Proteins; D011991:Receptors, Virus; C064035:ompW protein, E coli; C066743:Tsx protein, E coli; C482905:OmpX protein, E coli; D007501:Iron; D006867:Hydrolases