scholarly journals Modulation of Host Lipid Pathways by Pathogenic Intracellular Bacteria

Pathogens ◽  
2020 ◽  
Vol 9 (8) ◽  
pp. 614
Author(s):  
Paige E. Allen ◽  
Juan J. Martinez
Keyword(s):  
Host Cell ◽  
Mammalian Cells ◽  
Membrane Integrity ◽  
Membrane Microdomains ◽  
Intracellular Bacteria ◽  
Intracellular Pathogens ◽  
Cell Infection ◽  
Lipid Species ◽  
Host Plasma Membrane ◽  
Plasma Membrane Microdomains

Lipids are a broad group of molecules required for cell maintenance and homeostasis. Various intracellular pathogens have developed mechanisms of modulating and sequestering host lipid processes for a large array of functions for both bacterial and host cell survival. Among the host cell lipid functions that intracellular bacteria exploit for infection are the modulation of host plasma membrane microdomains (lipid rafts) required for efficient bacterial entry; the recruitment of specific lipids for membrane integrity of intracellular vacuoles; and the utilization of host lipid droplets for the regulation of immune responses and for energy production through fatty acid β-oxidation and oxidative phosphorylation. The majority of published studies on the utilization of these host lipid pathways during infection have focused on intracellular bacterial pathogens that reside within a vacuole during infection and, thus, have vastly different requirements for host lipid metabolites when compared to those intracellular pathogens that are released into the host cytosol upon infection. Here we summarize the mechanisms by which intracellular bacteria sequester host lipid species and compare the modulation of host lipid pathways and metabolites during host cell infection by intracellular pathogens residing in either a vacuole or within the cytosol of infected mammalian cells. This review will also highlight common and unique host pathways necessary for intracellular bacterial growth that could potentially be targeted for therapeutic intervention.

scholarly journals Characterization of Sec-Translocon-Dependent Extracytoplasmic Proteins of Rickettsia typhi

2008 ◽  
Vol 190 (18) ◽  
pp. 6234-6242 ◽  
Author(s):  
Nicole C. Ammerman ◽  
M. Sayeedur Rahman ◽  
Abdu F. Azad
Keyword(s):  
Host Cell ◽  
Mammalian Cells ◽  
Molecular Mechanisms ◽  
Host Cells ◽  
Transcriptional Analysis ◽  
Mammalian Host ◽  
Signal Peptides ◽  
Cell Infection ◽  
Rickettsia Typhi ◽  
Sec Translocon

ABSTRACT As obligate intracellular, vector-borne bacteria, rickettsiae must adapt to both mammalian and arthropod host cell environments. Deciphering the molecular mechanisms of the interactions between rickettsiae and their host cells has largely been hindered by the genetic intractability of these organisms; however, research in other gram-negative pathogens has demonstrated that many bacterial determinants of attachment, entry, and pathogenesis are extracytoplasmic proteins. The annotations of several rickettsial genomes indicate the presence of homologs of the Sec translocon, the major route for bacterial protein secretion from the cytoplasm. For Rickettsia typhi, the etiologic agent of murine typhus, homologs of the Sec-translocon-associated proteins LepB, SecA, and LspA have been functionally characterized; therefore, the R. typhi Sec apparatus represents a mechanism for the secretion of rickettsial proteins, including virulence factors, into the extracytoplasmic environment. Our objective was to characterize such Sec-dependent R. typhi proteins in the context of a mammalian host cell infection. By using the web-based programs LipoP, SignalP, and Phobius, a total of 191 R. typhi proteins were predicted to contain signal peptides targeting them to the Sec translocon. Of these putative signal peptides, 102 were tested in an Escherichia coli-based alkaline phosphatase (PhoA) gene fusion system. Eighty-four of these candidates exhibited signal peptide activity in E. coli, and transcriptional analysis indicated that at least 54 of the R. typhi extracytoplasmic proteins undergo active gene expression during infections of HeLa cells. This work highlights a number of interesting proteins possibly involved in rickettsial growth and virulence in mammalian cells.

scholarly journals Identification of a Gene That Affects the Efficiency of Host Cell Infection by Legionella pneumophila in a Temperature-Dependent Fashion

2003 ◽  
Vol 71 (11) ◽  
pp. 6256-6263 ◽  
Author(s):  
Dennis A. Ridenour ◽  
Suat L. G. Cirillo ◽  
Sheng Feng ◽  
Mustapha M. Samrakandi ◽  
Jeffrey D. Cirillo
Keyword(s):  
Host Cell ◽  
Legionella Pneumophila ◽  
Mammalian Cells ◽  
Growth Conditions ◽  
Host Cells ◽  
Secretion Systems ◽  
Cell Infection ◽  
Type Iv ◽  
Low Copy Number ◽  
Type Gene

ABSTRACT The ability to infect host cells is critical for the survival and replication of intracellular pathogens in humans. We previously found that many genes involved in the ability of Legionella pneumophila to infect macrophages are not expressed efficiently under standard laboratory growth conditions. We have developed an approach using expression of L. pneumophila genes from an exogenous constitutive promoter on a low-copy-number vector that allows identification of genes involved in host cell infection. Through the use of this strategy, we found that expression of a gene, lvhB2, enhances the efficiency of L. pneumophila infection of mammalian cells. The putative protein encoded by lvhB2 has similarity to structural pilin subunits of type IV secretion systems. We confirmed that this gene plays a role in host cell infection by the construction of an in-frame deletion in the L. pneumophila lvhB2 gene and complementation of this mutant with the wild-type gene. The lvhB2 mutant does not display a very obvious defect in interactions with host cells when the bacteria are grown at 37°C, but it has an approximately 100-fold effect on entry and intracellular replication when grown at 30°C. These data suggest that lvhB2 plays an important role in the efficiency of host cell infection by L. pneumophila grown at lower temperatures.

scholarly journals Molecular Characterization of Serine-, Alanine-, and Proline-Rich Proteins of Trypanosoma cruzi and Their Possible Role in Host Cell Infection

2006 ◽  
Vol 74 (3) ◽  
pp. 1537-1546 ◽  
Author(s):  
Renata C. P. Baida ◽  
Márcia R. M. Santos ◽  
Mirian S. Carmo ◽  
Nobuko Yoshida ◽  
Danielle Ferreira ◽  
...  
Keyword(s):  
Trypanosoma Cruzi ◽  
Host Cell ◽  
Mammalian Cells ◽  
Receptor Interaction ◽  
Cell Infection ◽  
Extracellular Medium ◽  
Metacyclic Trypomastigotes ◽  
A Cell

ABSTRACT We previously reported the isolation of a novel protein gene family, termed SAP (serine-, alanine-, and proline-rich protein), from Trypanosoma cruzi. Aided by the availability of the completed genome sequence of T. cruzi, we have now identified 39 full-length sequences of SAP, six pseudogenes and four partial genes. SAPs share a central domain of about 55 amino acids and can be divided into four groups based on their amino (N)- and carboxy (C)-terminal sequences. Some SAPs have conserved N- and C-terminal domains encoding a signal peptide and a glycosylphosphatidylinositol anchor addition site, respectively. Analysis of the expression of SAPs in metacyclic trypomastigotes by two-dimensional electrophoresis and immunoblotting revealed that they are likely to be posttranslationally modified in vivo. We have also demonstrated that some SAPs are shed into the extracellular medium. The recombinant SAP exhibited an adhesive capacity toward mammalian cells, where binding was dose dependent and saturable, indicating a possible ligand-receptor interaction. SAP triggered the host cell Ca2+ response required for parasite internalization. A cell invasion assay performed in the presence of SAP showed inhibition of internalization of the metacyclic forms of the CL strain. Taken together, these results show that SAP is involved in the invasion of mammalian cells by metacyclic trypomastigotes, and they confirm the hypothesis that infective trypomastigotes exploit an arsenal of surface glycoproteins and shed proteins to induce signaling events required for their internalization.

scholarly journals Engineered endosymbionts capable of directing mammalian cell gene expression

2021 ◽  
Author(s):  
Cody S. Madsen ◽  
Ashley V. Makela ◽  
Emily M. Greeson ◽  
Jonathan W. Hardy ◽  
Christopher H. Contag
Keyword(s):  
Gene Expression ◽  
Transcription Factors ◽  
Immune Responses ◽  
Host Cell ◽  
Mammalian Cells ◽  
Intracellular Bacteria ◽  
Cell Fates ◽  
Cell Gene Expression ◽  
Cell Gene ◽  
Mammalian Gene Expression

SummaryModular methods for directing mammalian gene expression would enable advances in tissue regeneration, enhance cell-based therapeutics and improve modulation of immune responses. To address this challenge, engineered endosymbionts (EES) that escape endosomal destruction, reside in the cytoplasm of mammalian cells, and secrete proteins that are transported to the nucleus to control host cell gene expression were developed. Microscopy confirmed that EES escape phagosomes, replicate within the cytoplasm, and can secrete reporter proteins into the cytoplasm that were then transported to the nucleus. Synthetic operons encoding the mammalian transcription factors, Stat-1 and Klf6 or Klf4 and Gata-3 were recombined into the EES genome. Using controlled induction, these EES were shown to direct gene expression in J774A.1 macrophage/monocyte cells and modulate the host cell fates. Expressing mammalian transcription factors from engineered intracellular bacteria as endosymbionts comprises a new tool for directing host cell gene expression for therapeutic and research purposes.Graphical abstract

The Infection of Cells by Bullet-Shaped Viruses

1969 ◽  
Vol 27 ◽  
pp. 372-373
Author(s):  
Frederick A. Murphy ◽  
Alyne K. Harrison ◽  
Sylvia G. Whitfield
Keyword(s):  
Electron Microscopy ◽  
Physical Properties ◽  
Host Cell ◽  
Thin Section ◽  
Cultured Cells ◽  
Cell Infection ◽  
Thin Section Electron Microscopy ◽  
Section Electron ◽  
Section Electron Microscopy

The bullet-shaped viruses are currently classified together on the basis of similarities in virion morphology and physical properties. Biologically and ecologically the member viruses are extremely diverse. In searching for further bases for making comparisons of these agents, the nature of host cell infection, both in vivo and in cultured cells, has been explored by thin-section electron microscopy.

COVID 19 – Eye Issues

2020 ◽  
Vol 5 (Special) ◽  
Keyword(s):  
Host Cell ◽  
Target Cell ◽  
Cell Receptor ◽  
Human Tissues ◽  
Type Ii ◽  
Cell Infection ◽  
Host Cell Receptor ◽  
Infected Cells ◽  
Cellular Entry

The coronavirus illness (COVID-19) is caused by a new recombinant SARS-CoV (SARS-CoV) virus (SARS-CoV-2). Target cell infection by SARS-CoV is mediated by the prickly protein of the coronavirus and host cell receptor, enzyme 2 converting angiotensin (ACE2) [3]. Similarly, a recent study suggests that cellular entry by SARS-CoV-2 is dependent on both ACE2 as well as type II transmembrane axial protease (TMPRSS2) [4]. This means that detection of ACE2 and PRSS2 expression in human tissues can predict potential infected cells and their respective effects in COVID-19 patients [1].

scholarly journals Neutralizing aptamers block S/RBD‐ACE2 interactions and prevent host cell infection

2021 ◽  
Author(s):  
Xiaohui Liu ◽  
Yi-ling Wang ◽  
Jacky Wu ◽  
Jianjun Qi ◽  
Zihua Zeng ◽  
...  
Keyword(s):  
Host Cell ◽  
Cell Infection

Eimeria tenella microneme protein EtMIC3: identification, localisation and role in host cell infection

2005 ◽  
Vol 140 (1) ◽  
pp. 43-53 ◽  
Author(s):  
M. Labbé ◽  
P. de Venevelles ◽  
F. Girard-Misguich ◽  
C. Bourdieu ◽  
A. Guillaume ◽  
...  
Keyword(s):  
Host Cell ◽  
Eimeria Tenella ◽  
Cell Infection ◽  
Microneme Protein

scholarly journals Flotillin microdomains interact with the cortical cytoskeleton to control uropod formation and neutrophil recruitment

2010 ◽  
Vol 191 (4) ◽  
pp. 771-781 ◽  
Author(s):  
Alexander Ludwig ◽  
Grant P. Otto ◽  
Kirsi Riento ◽  
Emily Hams ◽  
Padraic G. Fallon ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Ex Vivo ◽  
Neutrophil Migration ◽  
Neutrophil Recruitment ◽  
Membrane Microdomains ◽  
Neutrophil Chemotaxis ◽  
Myosin Iia ◽  
Plasma Membrane Microdomains ◽  
Cortical Cytoskeleton

We studied the function of plasma membrane microdomains defined by the proteins flotillin 1 and flotillin 2 in uropod formation and neutrophil chemotaxis. Flotillins become concentrated in the uropod of neutrophils after exposure to chemoattractants such as N-formyl-Met-Leu-Phe (fMLP). Here, we show that mice lacking flotillin 1 do not have flotillin microdomains, and that recruitment of neutrophils toward fMLP in vivo is reduced in these mice. Ex vivo, migration of neutrophils through a resistive matrix is reduced in the absence of flotillin microdomains, but the machinery required for sensing chemoattractant functions normally. Flotillin microdomains specifically associate with myosin IIa, and spectrins. Both uropod formation and myosin IIa activity are compromised in flotillin 1 knockout neutrophils. We conclude that the association between flotillin microdomains and cortical cytoskeleton has important functions during neutrophil migration, in uropod formation, and in the regulation of myosin IIa.

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