Facilitated diffusion of p-nitrophenyl-alpha-D-maltohexaoside through the outer membrane of Escherichia coli. Characterization of LamB as a specific and saturable channel for maltooligosaccharides.

Freundlieb, Sabine; Ehmann, U; Boos, Winfried

doi:10.1016/s0021-9258(19)57394-x

Cited by 74 publications

(15 citation statements)

References 43 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

“…We further tested the specificity of TM-P with lamB mutant E. coli, which is a mutant strain that lacks the outer membrane maltodextrin transporter lamB and cannot internalize maltodextrins. 37,38 As shown in Figure 6C, the mutant strain had a 2.5-fold decrease in uptake compared to wild-type E. coli. A fluorescent image of TM-P treated E. coli was also obtained to further validate the ability of E. coli to internalize TM-P (see Supporting Information, Figure S11).…”

Section: Stability Of Thiomaltosementioning

confidence: 88%

“…Thiomaltose should be internalized by a wide variety of oligosaccharide transporters, such as the maltodextrin transporters (lamB and others) and other general pores (OmpF, OmpC, and others). 37 We compared the uptake of TM-P against maltohexaose conjugated to perylene (MH-P), 22 as it was previously reported that longer oligosaccharides were less effectively internalized by E. coli. 39 As shown in Figure 6D, the uptake of TM-P is about 4−5-fold higher than MH-P, which is consistent with previous studies demonstrating that maltose is internalized more efficiently than maltohexaose.…”

Section: Stability Of Thiomaltosementioning

confidence: 99%

See 3 more Smart Citations

A Trimethoprim Conjugate of Thiomaltose Has Enhanced Antibacterial Efficacy In Vivo

et al. 2018

View full text Add to dashboard Cite

Trimethoprim is one of the most widely used antibiotics in the world. However, its efficacy is frequently limited by its poor water solubility and dose limiting toxicity. Prodrug strategies based on conjugation of oligosaccharides to trimethoprim have great potential for increasing the solubility of trimethoprim and lowering its toxicity, but they have been challenging to develop due to the sensitivity of trimethoprim to chemical modifications, and the rapid degradation of oligosaccharides in serum. In this report, we present a trimethoprim conjugate of maltodextrin termed TM-TMP, which increased the water solubility of trimethoprim by over 100 times, was stable to serum enzymes, and was active against urinary tract infections in mice. TM-TMP is composed of thiomaltose conjugated to trimethoprim, via a self-immolative disulfide linkage, and releases 4′-OH-trimethoprim (TMP-OH) after disulfide cleavage, which is a known metabolic product of trimethoprim and is as potent as trimethoprim. TM-TMP also contains a new maltodextrin targeting ligand composed of thiomaltose, which is stable to hydrolysis by serum amylases and therefore has the metabolic stability needed for in vivo use. TM-TMP has the potential to significantly improve the treatment of a wide number of infections given its high water solubility and the widespread use of trimethoprim.

show abstract

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Stability Of Thiomaltosementioning

confidence: 88%

Section: Stability Of Thiomaltosementioning

confidence: 99%

See 2 more Smart Citations

A Trimethoprim Conjugate of Thiomaltose Has Enhanced Antibacterial Efficacy In Vivo

et al. 2018

View full text Add to dashboard Cite

show abstract

“…In addition, because of very high concentrations of the maltose binding protein MalE, which scavenges for maltose in the periplasm, the great majority of maltose in the periplasm is bound rather than free. Therefore, when maltose is present in micromolar concentrations in the environment, there are estimated to be significantly lower concentrations of free maltose within the periplasm (24,26,(30)(31)(32)(33)(34). Indeed, Tan and coworkers recently suggested that the periplasmic concentration of free maltose must be lower than the extracellular concentration, based on a discrepancy they found when fitting data of E. coli capillary assays to their population-level chemotaxis model, which accounted for indirect binding (35).…”

Section: Introductionmentioning

confidence: 99%

Bacterial chemotaxis to saccharides is governed by a trade-off between sensing and uptake

Norris

Alcolombri

et al. 2021

Preprint

View full text Add to dashboard Cite

To swim up gradients of nutrients, E. coli senses nutrient concentrations within its periplasm. For small nutrient molecules, periplasmic concentrations typically match extracellular concentrations. However, this is not necessarily the case for saccharides, such as maltose, which is transported into the periplasm via a specific porin. Previous observations have shown that under various conditions E. coli limits maltoporin abundance so that, for extracellular micromolar concentrations of maltose, there are predicted to be only nanomolar concentrations of free maltose in the periplasm. Thus, in the micromolar regime, the total uptake of maltose from the external environment into the cytoplasm is limited not by the abundance of cytoplasmic transport proteins but by the abundance of maltoporins. Here we present results from experiments and modeling showing that this porin-limited transport enables E. coli to sense micromolar gradients of maltose despite having a high-affinity ABC transport system that is saturated at these micromolar levels. We used microfluidic assays to study chemotaxis of E. coli in various gradients of maltose and methyl-aspartate and leveraged our experimental observations to develop a mechanistic transport-and-sensing chemotaxis model. Incorporating this model into agent-based simulations, we discover a trade-off between uptake and sensing: although high-affinity transport enables higher uptake rates at low nutrient concentrations, it severely limits dynamic sensing range. We thus propose that E. coli may limit periplasmic uptake to increase its chemotactic sensitivity, enabling it to use maltose as an environmental cue.Statement of SignificanceBacterial chemotaxis is among the best-studied systems in biology and is paradigmatic of the mechanisms used by cells to link sensory inputs with regulated responses, thus providing insight into the ecological basis of cellular physiology. Here we present a mechanistic chemotaxis model that describes how the regulation of the transport of a sugar into and out of the cell’s periplasm affects the cell’s motile response to that sugar. Based on observations from population-level chemotaxis assays, we uncover an ecologically relevant trade-off between sensing and uptake. The general finding of this work is that, while high-affinity transport allows for higher uptake rates, it can severely limit the cell’s dynamic sensing range.

show abstract

Purification and Characterization

Tsai

2006

Biomacromolecules

208

View full text Add to dashboard Cite

Idiomarina loihiensis was isolated from the salt works in Sfax (Tunisia), until now, the characterization of the GAPDH phosphorylante was never studied. Here, we report the isolation and the biochemical characterization of glyceralehyde-3-phosphate dehydrogenase (GAPDH) from I. loihiensis saline's bacteria on the basis of the apparent native and subunit molecular weights, physico-chemical and kinetic characterizations. The purification method consisted of two steps, ammonium sulfate fractionation followed by one chromatographic step, namely dye-affinity on Blue Sepharose CL-6B. Polyclonal antibodies against the purified enzyme were used to recognize the I. loihiensis GAPDH by Western blotting. The optimum pH of the purified enzyme was 8.5. Studies on the effect of temperatures revealed an enzyme increasing activity of about 45˚C. The molecular weight of the purified enzyme was 36 kDa determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Non-denaturing polyacrylamide gels yield a molecular weight of 147 kDa. The Michaelis constants for NAD + and D-glyceraldehyde-3-phosphate estimated was 19 μM and 3.1 μM, respectively. The maximal velocity of the purified enzyme was estimated to be 2.06 U/mg, approximately 6-fold increase in specific activity and a final yield of approximately 32.5%. The physicochemical properties of this GAPDH, being characterized, could be used in further studies.

show abstract

Facilitated diffusion of p-nitrophenyl-alpha-D-maltohexaoside through the outer membrane of Escherichia coli. Characterization of LamB as a specific and saturable channel for maltooligosaccharides.

Cited by 74 publications

References 43 publications

A Trimethoprim Conjugate of Thiomaltose Has Enhanced Antibacterial Efficacy In Vivo

A Trimethoprim Conjugate of Thiomaltose Has Enhanced Antibacterial Efficacy In Vivo

Bacterial chemotaxis to saccharides is governed by a trade-off between sensing and uptake

Purification and Characterization

Contact Info

Product

Resources

About