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The article cites a research study that examines the association between quorum sensing, a bacterial process that regulates population-scale behavior, and sugar metabolism in Escherichia coli. It found that HPr, a phosphocarrier protein key to the sugar phosphotransferase system of Escherichia coli, copurifies with kinase LsrK, establishing linkages between quorum sensing activity and sugar metabolism.

Antibacterial resistance is an issue of increasing severity as current antibiotics are losing their effectiveness and fewer antibiotics are being developed. New methods for combating bacterial virulence are required. Modulating molecular communication among bacteria can alter phenotype, including attachment to epithelia, biofilm formation, and even toxin production. Intercepting and modulating communication networks provide a means to attenuate virulence without directly interacting with the bacteria of interest. In this work, we target communication mediated by the quorum sensing (QS) bacterial autoinducer-2, AI-2. We have assembled a capsule of biological polymers alginate and chitosan, attached an AI-2 processing kinase, LsrK, and provided substrate, ATP, for enzymatic alteration of AI-2 in culture fluids. Correspondingly, AI-2 mediated QS activity is diminished. All components of this system are 'biofabricated'-they are biologically derived and their assembly is accomplished using biological means. Initially, component quantities and kinetics were tested as assembled in microtiter plates. Subsequently, the identical components and assembly means were used to create the 'artificial cell' capsules. The functionalized capsules, when introduced into populations of bacteria, alter the dynamics of the AI-2 bacterial communication, attenuating QS activated phenotypes. We envision the assembly of these and other capsules or similar materials, as means to alter QS activity in a biologically compatible manner and in many environments, including in humans. [ABSTRACT FROM AUTHOR]

ABSTRACT The Na+/Ca2+ exchanger provides a major Ca2+ extrusion pathway in excitable cells and plays a key role in the control of intracellular Ca2+ concentrations. In Canis familiaris, Na+/Ca2+ exchanger (NCX) activity is regulated by the binding of Ca2+ to two cytosolic Ca2+-binding domains, CBD1 and CBD2, such that Ca2+-binding activates the exchanger. Despite its physiological importance, little is known about the exchanger's global structure, and the mechanism of allosteric Ca2+-regulation remains unclear. It was found previously that for NCX in the absence of Ca2+ the two domains CBD1 and CBD2 of the cytosolic loop are flexibly linked, while after Ca2+-binding they adopt a rigid arrangement that is slightly tilted. A realistic model for the mechanism of the exchanger's allosteric regulation should not only address this property, but also it should explain the distinctive behavior of Drosophila melanogaster's sodium/calcium exchanger, CALX, for which Ca2+-binding to CBD1 inhibits Ca2+ exchange. Here, NMR spin relaxation and residual dipolar couplings were used to show that Ca2+ modulates CBD1 and CBD2 interdomain flexibility of CALX in an analogous way as for NCX. A mechanistic model for the allosteric Ca2+ regulation of the Na+/Ca2+ exchanger is proposed. In this model, the intracellular loop acts as an entropic spring whose strength is modulated by Ca2+-binding to CBD1 controlling ion transport across the plasma membrane. Proteins 2016; 84:580-590. © 2016 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

LipL32 is a major surface protein that is expressed during infection by pathogenic Leptospira. Here, the crystallization of recombinant LipL3221-272, which corresponds to the mature LipL32 protein minus its N-terminal lipid-anchored cysteine residue, is described. Selenomethionine-labelled LipL3221-272 crystals diffracted to 2.25 Å resolution at a synchrotron source. The space group was P3121 or P3221 and the unit-cell parameters were a = b = 126.7, c = 96.0 Å. [ABSTRACT FROM AUTHOR]

In addition to engineering new pathways for synthesis, synthetic biologists rewire cells to carry out "programmable" functions, an example being the creation of wound‐healing probiotics. Engineering regulatory circuits and synthetic machinery, however, can be deleterious to cell function, particularly if the "metabolic burden" is significant. Here, a synthetic regulatory circuit previously constructed to direct Escherichiacoli to swim toward hydrogen peroxide, a signal of wound generation, was shown to work even with coexpression of antibiotic resistance genes and genes associated with lactose utilization. We found, however, that cotransformation with a second vector constitutively expressing GFP (as a marker) and additionally conferring resistance to kanamycin and tetracycline resulted in slower velocity (Δ~6 μm/s) and dramatically reduced growth rate (Δ > 50%). The additional vector did not, however, alter the run‐and‐tumble ratio or directional characteristics of H2O2–dependent motility. The main impact of this additional burden was limited to slowing cell velocity and growth, suggesting that reprogrammed cell motility by minimally altering native regulatory circuits can be maintained even when extraneous burden is placed on the host cell. © 2019 American Institute of Chemical Engineers Biotechnol. Prog., 35: e2778, 2019. [ABSTRACT FROM AUTHOR]

The Na(+) /Ca(2+) exchanger provides a major Ca(2+) extrusion pathway in excitable cells and plays a key role in the control of intracellular Ca(2+) concentrations. In Canis familiaris, Na(+) /Ca(2+) exchanger (NCX) activity is regulated by the binding of Ca(2+) to two cytosolic Ca(2+) -binding domains, CBD1 and CBD2, such that Ca(2+) -binding activates the exchanger. Despite its physiological importance, little is known about the exchanger's global structure, and the mechanism of allosteric Ca(2+) -regulation remains unclear. It was found previously that for NCX in the absence of Ca(2+) the two domains CBD1 and CBD2 of the cytosolic loop are flexibly linked, while after Ca(2+) -binding they adopt a rigid arrangement that is slightly tilted. A realistic model for the mechanism of the exchanger's allosteric regulation should not only address this property, but also it should explain the distinctive behavior of Drosophila melanogaster's sodium/calcium exchanger, CALX, for which Ca(2+) -binding to CBD1 inhibits Ca(2+) exchange. Here, NMR spin relaxation and residual dipolar couplings were used to show that Ca(2+) modulates CBD1 and CBD2 interdomain flexibility of CALX in an analogous way as for NCX. A mechanistic model for the allosteric Ca(2+) regulation of the Na(+) /Ca(2+) exchanger is proposed. In this model, the intracellular loop acts as an entropic spring whose strength is modulated by Ca(2+) -binding to CBD1 controlling ion transport across the plasma membrane., (© 2016 Wiley Periodicals, Inc.)