Secretion of the overproduced periplasmic PhoA protein into the medium and accumulation of its precursor in phoA-transformed Escherichia coli strains: involvement of outer membrane vesicles

Nesmeyanova, M. A.; Tsfasman, I. M.; Karamyshev, A. L.; Сузина, Н. Е.

doi:10.1007/bf00329408

Cited by 23 publications

(11 citation statements)

References 31 publications

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“…The periplasmic nonspecific acid phosphatases are known to concentrate at cell poles in Gram-negative bacteria (41)(42)(43). In accordance with this, the E. coli(pPN1) cells under GC1 displayed a periplasmic location of the precipitate at the poles (within the cells).…”

Section: Discussionmentioning

confidence: 58%

Interaction of Uranium with Bacterial Cell Surfaces: Inferences from Phosphatase-Mediated Uranium Precipitation

Kulkarni

Misra

Gupta

et al. 2016

Appl Environ Microbiol

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Deinococcus radiodurans and Escherichia coli expressing either PhoN, a periplasmic acid phosphatase, or PhoK, an extracellular alkaline phosphatase, were evaluated for uranium (U) bioprecipitation under two specific geochemical conditions (GCs): (i) a carbonate-deficient condition at near-neutral pH (GC1), and (ii) a carbonate-abundant condition at alkaline pH (GC2). Transmission electron microscopy revealed that recombinant cells expressing PhoN/PhoK formed cell-associated uranyl phosphate precipitate under GC1, whereas the same cells displayed extracellular precipitation under GC2. These results implied that the cell-bound or extracellular location of the precipitate was governed by the uranyl species prevalent at that particular GC, rather than the location of phosphatase. MINTEQ modeling predicted the formation of predominantly positively charged uranium hydroxide ions under GC1 and negatively charged uranyl carbonate-hydroxide complexes under GC2. Both microbes adsorbed 6-to 10-fold more U under GC1 than under GC2, suggesting that higher biosorption of U to the bacterial cell surface under GC1 may lead to cell-associated U precipitation. In contrast, at alkaline pH and in the presence of excess carbonate under GC2, poor biosorption of negatively charged uranyl carbonate complexes on the cell surface might have resulted in extracellular precipitation. The toxicity of U observed under GC1 being higher than that under GC2 could also be attributed to the preferential adsorption of U on cell surfaces under GC1. This work provides a vivid description of the interaction of U complexes with bacterial cells. The findings have implications for the toxicity of various U species and for developing biological aqueous effluent waste treatment strategies. IMPORTANCEThe present study provides illustrative insights into the interaction of uranium (U) complexes with recombinant bacterial cells overexpressing phosphatases. This work demonstrates the effects of aqueous speciation of U on the biosorption of U and the localization pattern of uranyl phosphate precipitated as a result of phosphatase action. Transmission electron microscopy revealed that location of uranyl phosphate (cell associated or extracellular) was primarily influenced by aqueous uranyl species present under the given geochemical conditions. The data would be useful for understanding the toxicity of U under different geochemical conditions. Since cell-associated precipitation of metal facilitates easy downstream processing by simple gravitybased settling down of metal-loaded cells, compared to cumbersome separation techniques, the results from this study are of considerable relevance to effluent treatment using such cells. Bioremediation strategies, such as bioreduction (1-3), biosorption (4-8), bioaccumulation (9, 10), and bioprecipitation (5, 11, 12, 13), have been studied for their potential to immobilize U from solutions. There is also a large body of work on microbial interactions with uranium relevant to environmental in situ bioremediation. The...

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Section: Discussionmentioning

confidence: 58%

Interaction of Uranium with Bacterial Cell Surfaces: Inferences from Phosphatase-Mediated Uranium Precipitation

Kulkarni

Misra

Gupta

et al. 2016

Appl Environ Microbiol

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“…The phosphate ligand originates from the product of the phosphohydrolytic reaction; the mediating phosphatase, homologous to the phoN product of various other enterobacteria (Macaskie et al 1994b), was identified as atypical in preliminary (Hambling et al 1987) and comparative (Montgomery et al 1995) studies. The possible biotechnological application of this class of phosphatase prompted this fundamental study of the properties of the Citrobacter enzyme and its comparison to that described in Salmonella typhimurium (Kier et al 1977a(Kier et al ,b, 1979Weppelman et al 1977) and alkaline phosphatase processing-related phenomena described in Escherichia coli (Nesmeyanova et al 1991(Nesmeyanova et al , 1994.…”

Section: Introductionmentioning

confidence: 96%

Purification and chacterization of acid-type phosphatases from a heavy-metal-accumulating Citrobacter sp.

Jeong

Poole

Willis

et al. 1998

Archives of Microbiology

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An acid phosphatase from a heavy-metal-accumulating strain of a Citrobacter sp. was resolved into two forms on the basis of their nonbinding (phosphatase I) or binding (phosphatase II) behaviour on the cation-exchange resin SP-Sephadex C50. Both holoenzymes had a molecular mass of 103-108 kDa as determined by Superose Q-6 column chromatography in the presence of 150 mM KCl and a subunit molecular mass of 27 kDa as determined by SDS-PAGE; the enzyme was tetrameric. Both enzymes had a pI approximately 9.0 and were immunologically cross-reactive. There were minor differences in amino acid composition and in peptide maps following tryptic digest. The pH optimum for phosphatases I and II was 5.5 and 6.25, respectively; phosphatase II alone retained activity at pH values up to 9.0. Phosphatase I was more resistant to mechanical shear, gamma-irradiation, high temperature, and toxins (F- and formaldehyde). Glycerol increased the thermostability of both enzymes, particularly the more thermosensitive phosphatase II. Phosphatase II had a lower Km and a lower Vmax for glycerol 2-phosphate hydrolysis. The production of enzyme isoforms is a phenomenon similar to that described previously for the alkaline phosphatase of Escherichia coli, where the isoforms relate to precursive and final processed forms of the enzyme. Acid phosphatase is physiologically distinct, with a role that is still obscure but that may relate to cellular stress responses.

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“…Recognition of signal sequences by a targeting factor is a very well coordinated and balanced process. When this balance is disrupted by overproduction of secretory proteins their precursors are accumulated in the cytoplasm in bacteria [21, 22]. In mammals, inability of a mutated protein to interact with SRP triggers a specific quality control mechanism, RAPP [23].…”

Section: Introductionmentioning

confidence: 99%

The Code for Directing Proteins for Translocation across ER Membrane: SRP Cotranslationally Recognizes Specific Features of a Signal Sequence

Nilsson

Lara

Hessa

et al. 2015

Journal of Molecular Biology

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The signal recognition particle (SRP) cotranslationally recognizes signal sequences of secretory proteins and targets ribosome-nascent chain complexes (RNCs) to the SRP receptor in the endoplasmic reticulum membrane, initiating translocation of the nascent chain through the Sec61 translocon. Although signal sequences do not have homology they have similar structural regions: a positively charged N-terminus, a hydrophobic core and a more polar C-terminal region that contains the cleavage site for the signal peptidase. Here, we have used site-specific photocrosslinking to study SRP-signal sequence interactions. A photoreactive probe was incorporated into the middle of wild-type or mutated signal sequences of the secretory protein preprolactin by in vitro translation of mRNAs containing an amber stop codon in the signal peptide in the presence of the Nε-(5-azido-2 nitrobenzoyl)-Lys-tRNAamb amber suppressor. A homogeneous population of SRP-ribosome-nascent chain complexes was obtained by the use of truncated mRNAs in translations performed in the presence of purified canine SRP. Quantitative analysis of the photoadducts revealed that charged residues at the N-terminus of the signal sequence or in the early part of the mature protein have only a mild effect on the SRP-signal sequence association. However, deletions of amino acid residues in the hydrophobic portion of the signal sequence severely affect SRP binding. The photocrosslinking data correlate with targeting efficiency and translocation across the membrane. Thus, the hydrophobic core of the signal sequence is primarily responsible for its recognition and binding by SRP, while positive charges fine-tune the SRP-signal sequence affinity and targeting to the translocon.

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Secretion of the overproduced periplasmic PhoA protein into the medium and accumulation of its precursor in phoA-transformed Escherichia coli strains: involvement of outer membrane vesicles

Cited by 23 publications

References 31 publications

Interaction of Uranium with Bacterial Cell Surfaces: Inferences from Phosphatase-Mediated Uranium Precipitation

Interaction of Uranium with Bacterial Cell Surfaces: Inferences from Phosphatase-Mediated Uranium Precipitation

Purification and chacterization of acid-type phosphatases from a heavy-metal-accumulating Citrobacter sp.

The Code for Directing Proteins for Translocation across ER Membrane: SRP Cotranslationally Recognizes Specific Features of a Signal Sequence

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