A Cycling<i>cis</i>-Golgi Protein Mediates Endosome-to-Golgi Traffic

Natarajan, Rajalaxmi; Linstedt, Adam D.

doi:10.1091/mbc.e04-05-0366

Cited by 55 publications

(64 citation statements)

References 36 publications

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“…This unique trafficking pathway may prevent these holotoxins from being exposed to the degradative environment of the late endosome/prelysosome compartment. Acidification of the endosomal compartment apparently is required for these vesicles to access this bypass pathway [45]. Therefore, the reduced stability of the Stx1 and Stx2 B subunits at pH 4, as observed in the nano-ES/MS experiments may be functionally important if disassembly of the holotoxins also is a necessary step in the cellular intoxication process.…”

Section: ϩ9mentioning

confidence: 97%

“…On binding to their cell surface Gb3 receptors, Stx1 and Stx2 are believed to be internalized into endosomes, which then transport the toxins, via a unique Golgi- directed bypass pathway, to their intracellular destination, the endoplasmic reticulum [45]. This unique trafficking pathway may prevent these holotoxins from being exposed to the degradative environment of the late endosome/prelysosome compartment.…”

Section: ϩ9mentioning

confidence: 99%

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Stability of the homopentameric b subunits of shiga toxins 1 and 2 in solution and the gas phase as revealed by nanoelectrospray fourier transform ion cyclotron resonance mass spectrometry

Kitova

Daneshfar

Marcato

et al. 2005

J. Am. Soc. Mass Spectrom.

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The assembly of the B subunits of Shiga toxins (Stx) 1 and 2 and the influence of solution conditions (protein concentration, temperature, pH, and ionic strength) on it are investigated using temperature-controlled nanoflow electrospray (nano-ES) ionization and Fourier-transform ion cyclotron resonance mass spectrometry. Despite the similar higher order structure predicted by X-ray crystallography analysis, the B 5 homopentamers of Stx1 and Stx2 exhibit differences in stability under the solution conditions investigated. At solution temperatures ranging from 0 to 60°C and subunit concentrations ranging from 5 to 85 M, the Stx1 B subunit exists almost entirely as the homopentamer in aqueous solutions, independent of the ionic strength. In contrast, the degree of assembly of Stx2 B subunit is strongly dependent on temperature, subunit concentration, and ionic strength. At subunit concentrations of more than 50 M, the Stx2 B subunit exists predominantly as a pentamer, although smaller multimers (dimer, trimer, and tetramer) are also evident. At lower concentrations, the Stx2 B subunit exists predominantly as monomer and dimer. The relative abundance of multimeric species of the Stx2 B subunit was insensitive to the ion source conditions, suggesting that gas-phase dissociation of the pentamer ions in the source does not influence the mass spectrum. Blackbody infrared radiative dissociation of the protonated B 5 ions of Stx2 at the ϩ12 and ϩ13 charge states proceeds, at reaction temperatures of 120 to 180°C, predominantly by the ejection of a single subunit from the complex. Dissociation into dimer and trimer ions constitutes a minor pathway. It follows that the dimer and trimer ions and, likely, the monomer ions observed in the nano-ES mass spectra of Stx2 B subunit originated in solution and not from gas-phase reactions. It is concluded that, under the solution conditions investigated, the homopentamer of Stx2 B subunit is thermodynamically less stable than that of Stx1 B subunit. Arrhenius activation parameters determined for the protonated Stx2 B 5 ions at the ϩ12 and ϩ13 charge states were compared with values reported for the corresponding B 5 ions of Stx1 B subunit. In contrast to the differential stability of the Stx1 and Stx2 B pentamers in solution, the dissociation activation energies (E a ) determined for the gaseous complexes are indistinguishable at a given charge state. The similarity in the E a values suggests that the protonated pentamer ions of both toxins are stabilized by similar intersubunit interactions in the gas phase, a result that is in agreement with the X-ray crystal structures of the holotoxins. (J Am Soc Mass Spectrom 2005, 16, 1957

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Section: ϩ9mentioning

confidence: 97%

Section: ϩ9mentioning

confidence: 99%

Stability of the homopentameric b subunits of shiga toxins 1 and 2 in solution and the gas phase as revealed by nanoelectrospray fourier transform ion cyclotron resonance mass spectrometry

Kitova

Daneshfar

Marcato

et al. 2005

J. Am. Soc. Mass Spectrom.

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“…3B). Both Ab uptake and internalization rate assays (8,23) determined that WT, TGN4mut, and ER4mut behaved similarly, demonstrating these activities were not affected by the extra cytoplasmic sequences ( Fig. 3 and data not shown).…”

Section: Creation and Localization Of Redirected Prebcr Complexesmentioning

confidence: 78%

“…An anti-Ig Ab uptake assay was used to further characterize any surface expression of redirected preBCRs (23). In this assay, the relative total amount of a conjugated anti-Ig Ab internalized over a given time period is measured.…”

Section: Creation and Localization Of Redirected Prebcr Complexesmentioning

confidence: 99%

Precursor B Cell Receptor Signaling Activity Can Be Uncoupled from Surface Expression

Güloğlu¹,

Roman

2006

The Journal of Immunology

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Signals from the precursor BCR (preBCR) cause proliferation and differentiation of progenitor (pro-) B cells into pre-B cells. Given the very low amounts of surface preBCRs and the demonstrated cell autonomy of preBCR signaling, we examined the possible occurrence of preBCR signal propagation from intracellular membranes such as the endoplasmic reticulum (ER) and the trans-Golgi network (TGN) in transformed and primary pro-B cells. PreBCRs composed of normal Ig μ or truncated Dμ heavy chains (HCs) were redirected to intracellular sites via localization sequences appended to the HC cytoplasmic tail. PreBCR complexes retained in the TGN or shunted from the TGN to lysosomes were as or 50% as active as the corresponding wild-type preBCRs in directing preBCR-dependent events, including CD2 and CD22 expression and proliferation in primary pro-B cells. This occurred despite their low to undetectable surface expression in transformed cells, which otherwise allowed significant surface accumulation of wild-type preBCRs. In contrast, ER-retained preBCRs were inactive. These results suggest that preBCR signaling is remarkably tolerant of dramatic changes in its subcellular distribution within post-ER compartments and support the possibility that the preBCR can activate signaling pathways in the TGN as well as the plasma membrane.

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“…Stx has been shown to utilize the direct pathway to the TGN, and not the Rab9-dependent pathway via late endosomes that transports amongst others, furin and a fraction of Pseudomonas exotoxin A [48,[52][53][54][55]. However, based on the differential requirements for retrograde transport of Stx, ricin and TGN38, it seems that more than one parallel pathway between early endosomes and the TGN may exist [32,33,[56][57][58][59][60][61][62].…”

Section: Endosome-to-golgi Transport Of Stxmentioning

confidence: 99%

The Intracellular Journey of Shiga Toxins

Torgersen¹

2013

TOTNJ

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Abstract:The Shiga toxin family consists of Shiga toxin (Stx) that is produced as a virulence factor by Shigella dysenteriae, and the Shiga-like toxins produced by certain strains of enterohemorrhagic E. coli as well as by some other types of bacteria. Infection with bacteria producing these toxins is a threat to human health even in industrialized countries, as the initial diarrhea caused by the infection might be followed by a complication named hemolytic uremic syndrome. The Shiga toxins consist of a binding moiety that in most cases binds to the glycosphingolipid Gb3 on the surface of susceptible cells, and an A-moiety responsible for the toxic effect in the cytosol. In order to reach its cytosolic target, the toxin must be internalized and then transported via the retrograde pathway to the Golgi complex and further to the endoplasmic reticulum. From the endoplasmic reticulum the enzymatically active part of the A-moiety is translocated to the cytosol, and cellular protein synthesis is inhibited. Although the Shiga toxins are involved in disease, they may also be exploited for medical diagnosis and treatment. Interestingly, the toxin receptor, Gb3, has a limited expression in normal tissues, but is overexpressed in several types of cancer. Thus, the use of Shiga toxin, or the binding part of the toxin, has great potential in cancer diagnostics and treatment. Furthermore, studies of the various uptake mechanisms and intracellular transport pathways exploited by the toxins, provide important insight in basic cell biology processes.

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A Cyclingcis-Golgi Protein Mediates Endosome-to-Golgi Traffic

Cited by 55 publications

References 36 publications

Stability of the homopentameric b subunits of shiga toxins 1 and 2 in solution and the gas phase as revealed by nanoelectrospray fourier transform ion cyclotron resonance mass spectrometry

Stability of the homopentameric b subunits of shiga toxins 1 and 2 in solution and the gas phase as revealed by nanoelectrospray fourier transform ion cyclotron resonance mass spectrometry

Precursor B Cell Receptor Signaling Activity Can Be Uncoupled from Surface Expression

The Intracellular Journey of Shiga Toxins

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