Quantitative analysis of proton-linked transport systems. The lactose permease of <i>Escherichia coli</i>

Booth, Ian R.; Mitchell, W.J.; Hamilton, W. Allan

doi:10.1042/bj1820687

Cited by 143 publications

(138 citation statements)

References 40 publications

(49 reference statements)

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“…Increasing the external pH is known to simultaneously decrease ApH and increase At (15,16). Table 1 shows that At changes occurred in a similar manner between pH 6.9 and 8.2.…”

Section: "mentioning

confidence: 63%

Membrane potential changes during the first steps of coliphage infection.

Labedan¹,

Letellìer²

1981

Proc. Natl. Acad. Sci. U.S.A.

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Immediately after adsorption, phages T4 and T5 induce a partial depolarization ofthe host cytoplasmic membrane. Infected bacteria respond to this phage-induced effect by a repolarization that leads to a new steady state of reduced membrane potential. The rate and extent ofrepolarization are adjusted to the intensity of depolarization, which depends on the number of adsorbed phages. Consequently, the new steady state membrane potential is attained in the same interval of time regardless of the maximum depolarization. These membrane potential changes appear to be independent of phage-specific properties (type of phage, presence of DNA and internal proteins, injection process) and of several membrane-related parameters (temperature, external pH, preinfectious level of membrane potential). We propose that phage adsorption to the outer membrane triggers the emission of a signal that is transmitted to the cytoplasmic membrane. Additivity of independent signals is possible when stimuli (phages) are added at the same time. Additional adsorption of phages has no further depolarizing effect as soon as the repolarization begins. We propose that this refractoriness to secondary depolarization and the shut-offofthe first depolarization are induced by the same chemical modification also initiated by adsorption of the first phage.The first steps ofmany coliphage infections involve interactions of different phage organelles with successive levels of the hostcell envelope and finally lead to release of the DNA, which is then transported through the cytoplasmic membrane (1). Though the early stages ofadsorption are relatively well known, the steps immediately preceding DNA injection and the injection process itself are poorly understood. Nevertheless, it was recently shown that phage T4 DNA is not injected in the absence ofa protonmotive force established across the cytoplasmic membrane of the host (2). This protonmotive force (3) is composed ofa membrane potential difference (AT) and ofa chemical difference in proton concentration (ApH). It was recently demonstrated that T4 injection is independent of ApH (2) and occurs above a threshold ofAT (4).To specify which step ofDNA injection depends upon AT we monitored AT continuously after infection by using a cyanine dye as a specific probe (5,6). Cyanine dyes are fluorescent permeant cations whose distribution between cells and medium reflects the membrane potential and whose intracellular accumulation leads to the formation of nonfluorescent dimers or aggregates (6). Thus, the amplitude ofthe fluorescence quenching is qualitatively related to AT. Moreover, a quantitative estimate ofAT can be obtained by using an external calibration (to be published).In this paper we show-that phage infection induces a rapid but partial depolarization of the host cytoplasmic membrane followed by a repolarization, leading to a new steady state reduced potential.MATERIALS AND METHODS Strains. Escherichia coli B and F (from our collection) are hosts which adsorb T4 and T5 phages rapidly. T4 g...

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“…Increasing the external pH is known to simultaneously decrease ApH and increase At (15,16). Table 1 shows that At changes occurred in a similar manner between pH 6.9 and 8.2.…”

Section: "mentioning

confidence: 63%

Membrane potential changes during the first steps of coliphage infection.

Labedan¹,

Letellìer²

1981

Proc. Natl. Acad. Sci. U.S.A.

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“…Further study of the presumed sucrose permease showed that it is most likely a sucrose/H+ syn-transporter as shown by similar stoichiometric ratios of H+ to [14C]sucrose uptake (0.83) to those of other syn-transporters such as the lactose permease of E. coli (West and Mitchell, 1973;Booth et al, 1979;Brooker et al, 1985) or the sucrose permease of Saccharomyces (Santos et al, 1982). Such a nearly stoichiometric ratio of H+ to sucrose transport further corroborates transport of sucrose by an active process, such as by a H+/sucrose syn-transporter.…”

Section: Discussionmentioning

confidence: 99%

Role of maltase in the utilization of sucrose by Candida albicans

Williamson

Huber

Bennett

1993

Biochemical Journal

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Two isoenzymes of maltase (EC 3.2.1.20) were purified to homogeneity from Candida albicans. Isoenzymes I and II were found to have apparent molecular masses of 63 and 66 kDa on SDS/PAGE with isoelectric points of 5.0 and 4.6 respectively. Both isoenzymes resembled each other in similar N-terminal sequence, specificity for the a(l -a4) glycosidic linkage and immune cross-reactivity on Western blots using a maltase II antigen-purified rabbit antibody. Maltase was induced by growth on sucrose whereas 8-fructofuranosidase activity could not be detected under similar conditions. Maltase I and II were shown to be unglycosylated enzymes by neutral sugar assay, and more than 90 % of ac-glucosidase activity was recoverable from spheroplasts. These data, in combination with other results from this INTRODUCTION

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“…Internal pH was estimated by measuring the distribution of a weak acid (radiolabeled salicylic acid) across the membrane (4,8,23). Salicylate has been used by us and others as a reliable indicator of internal pH (13,24,26,34,47).…”

Section: Methodsmentioning

confidence: 99%

Escherichia coli Glutamate- and Arginine-Dependent Acid Resistance Systems Increase Internal pH and Reverse Transmembrane Potential

2004

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Due to the acidic nature of the stomach, enteric organisms must withstand extreme acid stress for colonization and pathogenesis. Escherichia coli contains several acid resistance systems that protect cells to pH 2. One acid resistance system, acid resistance system 2 (AR2), requires extracellular glutamate, while another (AR3) requires extracellular arginine. Little is known about how these systems protect cells from acid stress. AR2 and AR3 are thought to consume intracellular protons through amino acid decarboxylation. Antiport mechanisms then exchange decarboxylation products for new amino acid substrates. This form of proton consumption could maintain an internal pH (pH i ) conducive to cell survival. The model was tested by estimating the pH i and transmembrane potential (⌬⌿) of cells acid stressed at pH 2.5. During acid challenge, glutamate-and arginine-dependent systems elevated pH i from 3.6 to 4.2 and 4.7, respectively. However, when pH i was manipulated to 4.0 in the presence or absence of glutamate, only cultures challenged in the presence of glutamate survived, indicating that a physiological parameter aside from pH i was also important. Measurements of ⌬⌿ indicated that amino acid-dependent acid resistance systems help convert membrane potential from an inside negative to inside positive charge, an established acidophile strategy used to survive extreme acidic environments. Thus, reversing ⌬⌿ may be a more important acid resistance strategy than maintaining a specific pH i value.

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Quantitative analysis of proton-linked transport systems. The lactose permease of Escherichia coli

Cited by 143 publications

References 40 publications

Membrane potential changes during the first steps of coliphage infection.

Membrane potential changes during the first steps of coliphage infection.

Role of maltase in the utilization of sucrose by Candida albicans

Escherichia coli Glutamate- and Arginine-Dependent Acid Resistance Systems Increase Internal pH and Reverse Transmembrane Potential

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