scholarly journals Global Regulation of the Salmonella enterica Serovar Typhimurium Major Porin, OmpD

2003 ◽  
Vol 185 (19) ◽  
pp. 5901-5905 ◽  
Author(s):  
Carlos A. Santiviago ◽  
Cecilia S. Toro ◽  
Alejandro A. Hidalgo ◽  
Philip Youderian ◽  
Guido C. Mora
Keyword(s):  
Outer Membrane ◽  
Salmonella Enterica ◽  
Catabolite Repression ◽  
Salmonella Enterica Serovar Typhimurium ◽  
Low Ph ◽  
Total Cell ◽  
Cell Protein ◽  
Global Regulation ◽  
Serovar Typhimurium ◽  
Ph Conditions

ABSTRACT The OmpD porin is the most abundant outer membrane protein in Salmonella enterica serovar Typhimurium and represents about 1% of total cell protein. Unlike the case with the less abundant OmpC and OmpF porins, the stoichiometry of OmpD in the outer membrane does not change in response to changes in osmolarity. The abundance of OmpD increases in response to anaerobiosis and decreases in response to low pH, conditions encountered by serovar Typhimurium during the infection of its murine host. By constructing an operon fusion of the lacZY genes with the ompD promoter, we show that the abundance of OmpD in the outer membrane is regulated primarily at the level of transcription and is subject to catabolite repression. In response to anaerobiosis, the abundance of OmpD in the outer membrane also appears to be controlled posttranscriptionally by a function dependent on Fnr.

scholarly journals Inhibition of Salmonella enterica Serovar Typhimurium Lipopolysaccharide Deacylation by Aminoarabinose Membrane Modification

2005 ◽  
Vol 187 (7) ◽  
pp. 2448-2457 ◽  
Author(s):  
Kiyoshi Kawasaki ◽  
Robert K. Ernst ◽  
Samuel I. Miller
Keyword(s):  
Outer Membrane ◽  
Salmonella Enterica ◽  
Lipid A ◽  
Bacterial Resistance ◽  
Salmonella Enterica Serovar Typhimurium ◽  
Host Recognition ◽  
Membrane Modification ◽  
Serovar Typhimurium ◽  
Nonionic Detergent

ABSTRACT Salmonella enterica serovar Typhimurium remodels the lipid A component of lipopolysaccharide, a major component of the outer membrane, to survive within animals. The activation of the sensor kinase PhoQ in host environments increases the synthesis of enzymes that deacylate, palmitoylate, hydroxylate, and attach aminoarabinose to lipid A, also known as endotoxin. These modifications promote bacterial resistance to antimicrobial peptides and reduce the host recognition of lipid A by Toll-like receptor 4. The Salmonella lipid A 3-O-deacylase, PagL, is an outer membrane protein whose expression is regulated by PhoQ. In S. enterica serovar Typhimurium strains that had the ability to add aminoarabinose to lipid A, 3-O-deacylated lipid A species were not detected, despite the PhoQ induction of PagL protein expression. In contrast, strains defective for the aminoarabinose modification of lipid A demonstrated in vivo PagL activity, indicating that this membrane modification inhibited PagL's enzymatic activity. Since not all lipid A molecules are modified with aminoarabinose upon PhoQ activation, these results cannot be ascribed to the substrate specificity of PagL. PagL-dependent deacylation was detected in sonically disrupted membranes and membranes treated with the nonionic detergent n-octyl-β-d-glucopyranoside, suggesting that perturbation of the intact outer membrane releases PagL from posttranslational inhibition by aminoarabinose-containing membranes. Taken together, these results suggest that PagL enzymatic deacylation is posttranslationally inhibited by membrane environments, which either sequester PagL from its substrate or alter its conformation.

scholarly journals The apeE Gene of Salmonella enterica Serovar Typhimurium Is Induced by Phosphate Limitation and Regulated by phoBR

2001 ◽  
Vol 183 (5) ◽  
pp. 1784-1786 ◽  
Author(s):  
Christopher A. Conlin ◽  
Seng L. Tan ◽  
Huajun Hu ◽  
Todd Segar
Keyword(s):  
Outer Membrane ◽  
Salmonella Enterica ◽  
Salmonella Enterica Serovar Typhimurium ◽  
Regulatory System ◽  
Phosphate Transport ◽  
Phosphate Limitation ◽  
Regulatory Locus ◽  
High Affinity ◽  
Serovar Typhimurium ◽  
Operon Expression

ABSTRACT Mutations in apeR, a regulatory locus of the outer membrane esterase apeE from Salmonella entericaserovar Typhimurium, were shown to be alleles of thepstSCAB-phoU high-affinity phosphate transport operon. Expression of apeE was induced by phosphate limitation, and this induction required the phoBR phosphate regulatory system.

Sign in / Sign up

Export Citation Format

Share Document