scholarly journals Erratum: Autophagy and endosomal trafficking inhibition by Vibrio cholerae MARTX toxin phosphatidylinositol-3-phosphate-specific phospholipase A1 activity

2015 ◽  
Vol 6 (1) ◽  
Author(s):  
Shivani Agarwal ◽  
Hyunjin Kim ◽  
Robin B. Chan ◽  
Shivangi Agarwal ◽  
Rebecca Williamson ◽  
...  
Keyword(s):  
Vibrio Cholerae ◽  
Endosomal Trafficking ◽  
Phospholipase A1 ◽  
Phosphatidylinositol 3

scholarly journals Autophagy and endosomal trafficking inhibition by Vibrio cholerae MARTX toxin phosphatidylinositol-3-phosphate-specific phospholipase A1 activity

2015 ◽  
Vol 6 (1) ◽  
Author(s):  
Shivani Agarwal ◽  
Hyunjin Kim ◽  
Robin B. Chan ◽  
Shivangi Agarwal ◽  
Rebecca Williamson ◽  
...  
Keyword(s):  
Vibrio Cholerae ◽  
Host Immune System ◽  
Endosomal Trafficking ◽  
Phospholipase A1 ◽  
Effector Domains ◽  
Pla1 Activity ◽  
Phosphatidylinositol 3

Abstract Vibrio cholerae, responsible for acute gastroenteritis secretes a large multifunctional-autoprocessing repeat-in-toxin (MARTX) toxin linked to evasion of host immune system, facilitating colonization of small intestine. Unlike other effector domains of the multifunctional toxin that target cytoskeleton, the function of alpha-beta hydrolase (ABH) remained elusive. This study demonstrates that ABH is an esterase/lipase with catalytic Ser–His–Asp triad. ABH binds with high affinity to phosphatidylinositol-3-phosphate (PtdIns3P) and cleaves the fatty acid in PtdIns3P at the sn1 position in vitro making it the first PtdIns3P-specific phospholipase A1 (PLA1). Expression of ABH in vivo reduces intracellular PtdIns3P levels and its PtdIns3P-specific PLA1 activity blocks endosomal and autophagic pathways. In accordance with recent studies acknowledging the potential of extracellular pathogens to evade or exploit autophagy to prevent their clearance and facilitate survival, this is the first report highlighting the role of ABH in inhibiting autophagy and endosomal trafficking induced by extracellular V. cholerae.

scholarly journals Rabenosyn-5, a Novel Rab5 Effector, Is Complexed with Hvps45 and Recruited to Endosomes through a Fyve Finger Domain

2000 ◽  
Vol 151 (3) ◽  
pp. 601-612 ◽  
Author(s):  
Erik Nielsen ◽  
Savvas Christoforidis ◽  
Sandrine Uttenweiler-Joseph ◽  
Marta Miaczynska ◽  
Frederique Dewitte ◽  
...  
Keyword(s):  
Early Endosome ◽  
Effector Proteins ◽  
Endosomal Trafficking ◽  
Membrane Domains ◽  
Phosphatidylinositol 3 Kinase ◽  
Early Endosomes ◽  
Site Of Action ◽  
Endosomal Membranes ◽  
Novel Protein ◽  
Phosphatidylinositol 3

Rab5 regulates endocytic membrane traffic by specifically recruiting cytosolic effector proteins to their site of action on early endosomal membranes. We have characterized a new Rab5 effector complex involved in endosomal fusion events. This complex includes a novel protein, Rabenosyn-5, which, like the previously characterized Rab5 effector early endosome antigen 1 (EEA1), contains an FYVE finger domain and is recruited in a phosphatidylinositol-3-kinase–dependent fashion to early endosomes. Rabenosyn-5 is complexed to the Sec1-like protein hVPS45. hVPS45 does not interact directly with Rab5, therefore Rabenosyn-5 serves as a molecular link between hVPS45 and the Rab5 GTPase. This property suggests that Rabenosyn-5 is a closer mammalian functional homologue of yeast Vac1p than EEA1. Furthermore, although both EEA1 and Rabenosyn-5 are required for early endosomal fusion, only overexpression of Rabenosyn-5 inhibits cathepsin D processing, suggesting that the two proteins play distinct roles in endosomal trafficking. We propose that Rab5-dependent formation of membrane domains enriched in phosphatidylinositol-3-phosphate has evolved as a mechanism for the recruitment of multiple effector proteins to mammalian early endosomes, and that these domains are multifunctional, depending on the differing activities of the effector proteins recruited.

scholarly journals Ca2+-regulated Pool of Phosphatidylinositol-3-phosphate Produced by Phosphatidylinositol 3-Kinase C2α on Neurosecretory Vesicles

2008 ◽  
Vol 19 (12) ◽  
pp. 5593-5603 ◽  
Author(s):  
Peter J. Wen ◽  
Shona L. Osborne ◽  
Isabel C. Morrow ◽  
Robert G. Parton ◽  
Jan Domin ◽  
...  
Keyword(s):  
Critical Role ◽  
Neurosecretory Cells ◽  
Secretory Vesicles ◽  
Endosomal Trafficking ◽  
Class Iii ◽  
Phosphatidylinositol 3 Kinase ◽  
Lipid Product ◽  
Phosphatidylinositol 3

Phosphatidylinositol-3-phosphate [PtdIns(3)P] is a key player in early endosomal trafficking and is mainly produced by class III phosphatidylinositol 3-kinase (PI3K). In neurosecretory cells, class II PI3K-C2α and its lipid product PtdIns(3)P have recently been shown to play a critical role during neuroexocytosis, suggesting that two distinct pools of PtdIns(3)P might coexist in these cells. However, the precise characterization of this additional pool of PtdIns(3)P remains to be established. Using a selective PtdIns(3)P probe, we have identified a novel PtdIns(3)P-positive pool localized on secretory vesicles, sensitive to PI3K-C2α knockdown and relatively resistant to wortmannin treatment. In neurosecretory cells, stimulation of exocytosis promoted a transient albeit large increase in PtdIns(3)P production localized on secretory vesicles sensitive to PI3K-C2α knockdown and expression of PI3K-C2α catalytically inactive mutant. Using purified chromaffin granules, we found that PtdIns(3)P production is controlled by Ca2+. We confirmed that PtdIns(3)P production from recombinantly expressed PI3K-C2α is indeed regulated by Ca2+. We provide evidence that a dynamic pool of PtdIns(3)P synthesized by PI3K-C2α occurs on secretory vesicles in neurosecretory cells, demonstrating that the activity of a member of the PI3K family is regulated by Ca2+ in vitro and in living neurosecretory cells.

scholarly journals Crystallization and preliminary X-ray crystallographic analysis of the PH-GRAM domain of human MTMR4

2014 ◽  
Vol 70 (9) ◽  
pp. 1280-1283
Author(s):  
Jee Un Lee ◽  
Ji Young Son ◽  
Ki-Young Yoo ◽  
Woori Shin ◽  
Dong-Won Im ◽  
...  
Keyword(s):  
Large Family ◽  
Crystallographic Analysis ◽  
Effector Proteins ◽  
Diffusion Method ◽  
Endosomal Trafficking ◽  
Cell Parameters ◽  
Lipid Kinases ◽  
Degradation Step ◽  
Related Proteins ◽  
Phosphatidylinositol 3

Phosphoinositide lipid molecules play critical roles in intracellular signalling pathways and are regulated by phospholipases, lipid kinases and phosphatases. In particular, phosphatidylinositol 3-phosphate and phosphatidylinositol 3,5-bisphosphate are related to endosomal trafficking events through the recruitment of effector proteins and are involved in the degradation step of autophagy. Myotubularin-related proteins (MTMRs) are a large family of phosphatases that catalyze the dephosphorylation of phosphatidylinositol 3-phosphate and phosphatidylinositol 3,5-bisphosphate at the D3 position, thereby regulating cellular phosphoinositide levels. In this study, the PH-GRAM domain of human MTMR4 was cloned, overexpressed inEscherichia coli, purified and crystallized by the vapour-diffusion method. The crystals diffracted to 3.20 Å resolution at a synchrotron beamline and belonged to either space groupP61orP65, with unit-cell parametersa=b= 109.10,c= 238.97 Å.

scholarly journals Sbf/MTMR13 coordinates PI(3)P and Rab21 regulation in endocytic control of cellular remodeling

2012 ◽  
Vol 23 (14) ◽  
pp. 2723-2740 ◽  
Author(s):  
Steve Jean ◽  
Sarah Cox ◽  
Eric J. Schmidt ◽  
Fred L. Robinson ◽  
Amy Kiger
Keyword(s):  
Endosomal Trafficking ◽  
Rab Gtpases ◽  
Nucleotide Exchange ◽  
Phosphatidylinositol 3 Kinase ◽  
Guanine Nucleotide Exchange ◽  
Nucleotide Exchange Factor ◽  
Membrane Compartment ◽  
Endosomal Pathway ◽  
Gtpase Activation ◽  
Phosphatidylinositol 3

Cells rely on the coordinated regulation of lipid phosphoinositides and Rab GTPases to define membrane compartment fates along distinct trafficking routes. The family of disease-related myotubularin (MTM) phosphoinositide phosphatases includes catalytically inactive members, or pseudophosphatases, with poorly understood functions. We found that Drosophila MTM pseudophosphatase Sbf coordinates both phosphatidylinositol 3-phosphate (PI(3)P) turnover and Rab21 GTPase activation in an endosomal pathway that controls macrophage remodeling. Sbf dynamically interacts with class II phosphatidylinositol 3-kinase and stably recruits Mtm to promote turnover of a PI(3)P subpool essential for endosomal trafficking. Sbf also functions as a guanine nucleotide exchange factor that promotes Rab21 GTPase activation associated with PI(3)P endosomes. Of importance, Sbf, Mtm, and Rab21 function together, along with Rab11-mediated endosomal trafficking, to control macrophage protrusion formation. This identifies Sbf as a critical coordinator of PI(3)P and Rab21 regulation, which specifies an endosomal pathway and cortical control.

In vivo Production of Soluble Inorganic Pyrophosphatases in Two Strains of Vibrio cholerae

1970 ◽  
Vol 24 (1) ◽  
pp. 38-41
Author(s):  
Taslima Taher Lina ◽  
Mohammad Ilias
Keyword(s):  
Vibrio Cholerae ◽  
Specific Activity ◽  
Experimental Conditions ◽  
Environmental Strain ◽  
Cell Extracts ◽  
Atcc Strain ◽  
The Family ◽  
Effects Of Ph ◽  
Vibrio Cholerae O1

The in vivo production of soluble inorganic pyrophosphatases (PPases) was investigated in two strains, namely, Vibrio cholerae EM 004 (environmental strain) and Vibrio cholerae O1 757 (ATCC strain). V. cholerae is known to contain both family I and family II PPase coding sequences. The production of family I and family II PPases were determined by measuring the enzyme activity in cell extracts. The effects of pH, temperature, salinity of the growth medium on the production of soluble PPases were studied. In case of family I PPase, V. cholerae EM 004 gave the highest specific activity at pH 9.0, with 2% NaCl + 0.011% NaF and at 37°C. The strain V. cholerae O1 757 gave the highest specific activity at pH 9.0, with media containing 0% NaCl and at 37°C. On the other hand, under all the conditions family II PPase did not give any significant specific activity, suggesting that the family II PPase was not produced in vivo in either strains of V. cholerae under different experimental conditions. Keywords: Vibrio cholerae, Pyrophosphatases (PPases), Specific activityDOI: http://dx.doi.org/10.3329/bjm.v24i1.1235 Bangladesh J Microbiol, Volume 24, Number 1, June 2007, pp 38-41

Exemplar Abstract for Vibrio cholerae Pacini 1854 (Approved Lists 1980).

2003 ◽  
Author(s):  
Charles Thomas Parker ◽  
Dorothea Taylor ◽  
George M Garrity
Keyword(s):  
Vibrio Cholerae

Exemplar Abstract for Vibrio cholerae Pacini 1854 (Approved Lists 1980).

2003 ◽  
Author(s):  
Charles Thomas Parker ◽  
Dorothea Taylor ◽  
George M Garrity
Keyword(s):  
Vibrio Cholerae
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