The role of the periplasmic maltose-binding protein and the outer-membrane phage λ receptor in maltodextrin transport of Escherichia coli

1980 ◽  
Vol 8 (6) ◽  
pp. 680-681 ◽  
Author(s):  
THOMAS FERENCI ◽  
JOHANNES BRASS ◽  
WINFRIED BOOS
Keyword(s):  
Escherichia Coli ◽  
Outer Membrane ◽  
Binding Protein ◽  
Maltose Binding Protein

scholarly journals MexAB-OprM Efflux Pump Interaction with the Peptidoglycan of Escherichia coli and Pseudomonas aeruginosa

2021 ◽  
Vol 22 (10) ◽  
pp. 5328
Author(s):  
Miao Ma ◽  
Margaux Lustig ◽  
Michèle Salem ◽  
Dominique Mengin-Lecreulx ◽  
Gilles Phan ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Pseudomonas Aeruginosa ◽  
Cell Division ◽  
Membrane Proteins ◽  
Outer Membrane ◽  
Efflux Pump ◽  
Gram Negative Bacteria ◽  
Gram Negative ◽  
Active Efflux

One of the major families of membrane proteins found in prokaryote genome corresponds to the transporters. Among them, the resistance-nodulation-cell division (RND) transporters are highly studied, as being responsible for one of the most problematic mechanisms used by bacteria to resist to antibiotics, i.e., the active efflux of drugs. In Gram-negative bacteria, these proteins are inserted in the inner membrane and form a tripartite assembly with an outer membrane factor and a periplasmic linker in order to cross the two membranes to expulse molecules outside of the cell. A lot of information has been collected to understand the functional mechanism of these pumps, especially with AcrAB-TolC from Escherichia coli, but one missing piece from all the suggested models is the role of peptidoglycan in the assembly. Here, by pull-down experiments with purified peptidoglycans, we precise the MexAB-OprM interaction with the peptidoglycan from Escherichia coli and Pseudomonas aeruginosa, highlighting a role of the peptidoglycan in stabilizing the MexA-OprM complex and also differences between the two Gram-negative bacteria peptidoglycans.

scholarly journals The Maltodextrin System of Escherichia coli: Metabolism and Transport

2005 ◽  
Vol 187 (24) ◽  
pp. 8322-8331 ◽  
Author(s):  
Renate Dippel ◽  
Winfried Boos
Keyword(s):  
Escherichia Coli ◽  
Abc Transporter ◽  
Binding Protein ◽  
Glycogen Synthesis ◽  
Equilibrium Conditions ◽  
Per Se ◽  
Maltodextrin Phosphorylase ◽  
Internal Level

ABSTRACT The maltose/maltodextrin regulon of Escherichia coli consists of 10 genes which encode a binding protein-dependent ABC transporter and four enzymes acting on maltodextrins. All mal genes are controlled by MalT, a transcriptional activator that is exclusively activated by maltotriose. By the action of amylomaltase, we prepared uniformly labeled [14C]maltodextrins from maltose up to maltoheptaose with identical specific radioactivities with respect to their glucosyl residues, which made it possible to quantitatively follow the rate of transport for each maltodextrin. Isogenic malQ mutants lacking maltodextrin phosphorylase (MalP) or maltodextrin glucosidase (MalZ) or both were constructed. The resulting in vivo pattern of maltodextrin metabolism was determined by analyzing accumulated [14C]maltodextrins. MalP− MalZ+ strains degraded all dextrins to maltose, whereas MalP+ MalZ− strains degraded them to maltotriose. The labeled dextrins were used to measure the rate of transport in the absence of cytoplasmic metabolism. Irrespective of the length of the dextrin, the rates of transport at a submicromolar concentration were similar for the maltodextrins when the rate was calculated per glucosyl residue, suggesting a novel mode for substrate translocation. Strains lacking MalQ and maltose transacetylase were tested for their ability to accumulate maltose. At 1.8 nM external maltose, the ratio of internal to external maltose concentration under equilibrium conditions reached 106 to 1 but declined at higher external maltose concentrations. The maximal internal level of maltose at increasing external maltose concentrations was around 100 mM. A strain lacking malQ, malP, and malZ as well as glycogen synthesis and in which maltodextrins are not chemically altered could be induced by external maltose as well as by all other maltodextrins, demonstrating the role of transport per se for induction.

scholarly journals Solution NMR assignment of LpoB, an outer-membrane anchored Penicillin-Binding Protein activator from Escherichia coli

2014 ◽  
Vol 9 (1) ◽  
pp. 123-127 ◽  
Author(s):  
Nicolas L. Jean ◽  
Catherine M. Bougault ◽  
Alexander J. F. Egan ◽  
Waldemar Vollmer ◽  
Jean-Pierre Simorre
Keyword(s):  
Escherichia Coli ◽  
Outer Membrane ◽  
Nmr Assignment ◽  
Binding Protein ◽  
Solution Nmr ◽  
Penicillin Binding Protein ◽  
Protein Activator
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