Figure 1.
LPS structure and transport in Escherichia coli.
A) Chemical structure of LPS. O-antigen is indicated in parenthesis as it is not synthesized in E. coli K12 derivatives. B) LPS transport from IM to OM. The MsbA protein catalyzes LPS flipping across the IM that is then exported to the cell surface by the Lpt machinery.
Figure 2.
Venn diagram of proteins distribution across strains and growth conditions analysed.
Proteins are identified from total membrane samples. wt, (PS201); LptC+ (PS202, araBp-lptC) grown under permissive condition (0,2% arabinose); LptC-depleted, PS202 grown under non permissive condition (without arabinose).
Table 1.
Envelope proteins exhibiting a significant variation upon LptC depletion: peptidoglycan synthesis/remodeling and cell division.
Figure 3.
AsmA protein abundance and subcellular localization.
PS201 (asmA-SPA lptC+) and PS202 (asmA-SPA araBp-lptC) cells were grown with or without arabinose as indicated. Total membrane protein extracts prepared as described in Materials and Methods were analysed by immunoblotting (panel A) or fractionated by sucrose density gradient (panel B). A) 10 µg of total membrane proteins were loaded in each lane. 55-kDa protein was used as loading control. B) Fractions were collected from the top of the gradient and immunoblotted using antibodies recognizing the 55-kDa protein as IM marker, LamB as OM marker. α-Flag antibodies were used to detect AsmA-SPA protein. wt, PS201; LptC+, PS202 (araBp-lptC) grown under permissive condition (with 0,2% arabinose); LptC-depleted, PS202 grown under non permissive condition (without arabinose).
Table 2.
Envelope proteins exhibiting a significant variation upon LptC depletion: cell envelope biogenesis.
Table 3.
AsmA level in membrane fractions.
Table 4.
Envelope proteins exhibiting a significant variation upon LptC depletion: transport/assembly.
Figure 4.
List of proteins belonging to cell envelope stress response pathways whose level changes upon LptC depletion.
A. Relative abundance is calculated as the ratio beetween FL905 grown under permissive and non permissive conditions: ↑, increased; ↓, decreased (see Tables 1, 2. 4). B. Venn diagram showing functions whose regulations is shared by multiple envelope signaling systems.