scholarly journals Overexpression of O‐polysaccharide chain length regulators in Gram‐negative bacteria using the Wzx‐/Wzy‐dependent pathway enhances production of defined modal length O‐polysaccharide polymers for use as haptens in glycoconjugate vaccines

2018 ◽  
Vol 125 (2) ◽  
pp. 575-585 ◽  
Author(s):  
N. Hegerle ◽  
J. Bose ◽  
G. Ramachandran ◽  
J.E. Galen ◽  
M.M. Levine ◽  
...  
Keyword(s):  
Chain Length ◽  
Gram Negative Bacteria ◽  
Gram Negative ◽  
Modal Length ◽  
Polysaccharide Chain ◽  
Glycoconjugate Vaccines ◽  
Dependent Pathway

scholarly journals New insights in caspase-11 functions in noncanonical inflammasome signalling

Inflammasome ◽  
2014 ◽  
Vol 1 (1) ◽  
Author(s):  
Mélanie Bodnar ◽  
Virginie Petrilli
Keyword(s):  
Cell Death ◽  
Inflammatory Cell ◽  
Protein Complexes ◽  
Inflammasome Activation ◽  
Gram Negative Bacteria ◽  
Nucleotide Binding Domain ◽  
Gram Negative ◽  
Caspase 1 ◽  
Nlrp3 Inflammasome Activation ◽  
Dependent Pathway

AbstractInflammasomes are multi-protein complexes that play a crucial role in innate immunity. They are assembled by cytosolic sensors of the Nucleotide-binding domain and Leucine-rich repeat containing Receptor (NLR) and PYrin and HIN (PYHIN) domain-containing protein families upon sensing various pathogens and danger signals. Inflammasome formation culminates in caspase-1 activation, which causes the cleavage of pro-IL-1β and pro- IL-18 into active cytokines; this eventually results in the induction of an inflammatory cell death called pyroptosis. Recent data using Gram-negative bacteria suggests a role for caspase-11 not only in NLRP3 inflammasome activation but also in a caspase-1- and inflammasome-independent cell death. This novel caspase-11-dependent pathway is critical to control infection by Gram-negative bacteria and has been named the noncanonical inflammasome.

scholarly journals Structural Determination and Genetic Identification of the O-Antigen from an Escherichia coli Strain, LL004, Representing a Novel Serogroup

2021 ◽  
Vol 22 (23) ◽  
pp. 12746
Author(s):  
Jing Wang ◽  
Yujuan Xu ◽  
Chunjun Qin ◽  
Jing Hu ◽  
Jian Yin ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Nmr Spectra ◽  
Coli Strain ◽  
Genetic Identification ◽  
Gram Negative Bacteria ◽  
Gram Negative ◽  
E Coli ◽  
O Antigen ◽  
Antigen Structure ◽  
Dependent Pathway

The O-antigen is the outermost component of the lipopolysaccharide layer in Gram-negative bacteria, and the variation of O-antigen structure provides the basis for bacterial serological diversity. Here, we determined the O-antigen structure of an Escherichia coli strain, LL004, which is totally different from all of the E. coli serogroups. The tetrasaccharide repeating unit was determined as →4)-β-d-Galp-(1→3)-β-d-GlcpNAc6OAc(~70%)-(1→3)-β-d-GalpA-(1→3)-β-d-GalpNAc-(1→ with monosaccharide analysis and NMR spectra. We also characterized the O-antigen gene cluster of LL004, and sequence analysis showed that it correlated well with the O-antigen structure. Deletion and complementation testing further confirmed its role in O-antigen biosynthesis, and indicated that the O-antigen of LL004 is assembled via the Wzx/Wzy dependent pathway. Our findings, in combination, suggest that LL004 should represent a novel serogroup of E. coli.

scholarly journals Reconstitution of surface lipoprotein translocation reveals Slam as an outer membrane translocon in Gram-negative bacteria

2021 ◽  
Author(s):  
Minh Sang Huynh ◽  
Yogesh Hooda ◽  
Yuzi Raina Li ◽  
Maciej Jagielnicki ◽  
Christine Chieh-Lin Lai ◽  
...  
Keyword(s):  
Outer Membrane ◽  
Gram Negative Bacteria ◽  
Gram Negative ◽  
Bacterial Surface ◽  
Outer Leaflet ◽  
Translocation Efficiency ◽  
Translocation Assay ◽  
Periplasmic Chaperone ◽  
Dependent Pathway

Surface lipoproteins (SLPs) are peripherally attached to the outer leaflet of the outer membrane in many Gram-negative bacteria, playing significant roles in nutrient acquisition and immune evasion in the host. While the factors that are involved in the synthesis and delivery of SLPs in the inner membrane are well characterized, the molecular machineries required for the movement of SLPs to the surface are still not fully elucidated. In this study, we investigated the translocation of a surface lipoprotein TbpB through a Slam1-dependent pathway. Using purified components, we developed an in vitro translocation assay where unfolded TbpB is transported through Slam1 containing proteoliposomes, confirming Slam1 as an outer membrane translocon. While looking to identify factors to increase translocation efficiency, we discovered the periplasmic chaperone Skp interacted with TbpB in the periplasm of Escherichia coli. The presence of Skp was found to increase the translocation efficiency of TbpB in the reconstituted translocation assays. A knockout of Skp in Neisseria meningitidis revealed that Skp is essential for functional translocation of TbpB to the bacterial surface. Taken together, we propose a pathway for surface destined lipoproteins, where Skp acts as a holdase for Slam-mediated TbpB translocation across the outer membrane.

scholarly journals The Net Charge of the First 18 Residues of the Mature Sequence Affects Protein Translocation across the Cytoplasmic Membrane of Gram-Negative Bacteria

2000 ◽  
Vol 182 (8) ◽  
pp. 2163-2169 ◽  
Author(s):  
Andrey V. Kajava ◽  
Sergey N. Zolov ◽  
Andrey E. Kalinin ◽  
Marina A. Nesmeyanova
Keyword(s):  
Cytoplasmic Membrane ◽  
Protein Translocation ◽  
Signal Sequence ◽  
Gram Negative Bacteria ◽  
Net Charge ◽  
Gram Negative ◽  
Hybrid Proteins ◽  
Almost All ◽  
Dependent Pathway ◽  
Practical Recommendations

ABSTRACT This statistical study shows that in proteins of gram-negative bacteria exported by the Sec-dependent pathway, the first 14 to 18 residues of the mature sequences have the highest deviation between the observed and expected net charge distributions. Moreover, almost all sequences have either neutral or negative net charge in this region. This rule is restricted to gram-negative bacteria, since neither eukaryotic nor gram-positive bacterial exported proteins have this charge bias. Subsequent experiments performed with a series ofEscherichia coli alkaline phosphatase mutants confirmed that this charge bias is associated with protein translocation across the cytoplasmic membrane. Two consecutive basic residues inhibit translocation effectively when placed within the first 14 residues of the mature protein but not when placed in positions 19 and 20. The sensitivity to arginine partially reappeared again 30 residues away from the signal sequence. These data provide new insight into the mechanism of protein export in gram-negative bacteria and lead to practical recommendations for successful secretion of hybrid proteins.

scholarly journals Unique Regions of the Polysaccharide Copolymerase Wzz2fromPseudomonas aeruginosaAre Essential for O-Specific Antigen Chain Length Control

2019 ◽  
Vol 201 (15) ◽  
Author(s):  
Steven M. Huszczynski ◽  
Chelsea Coumoundouros ◽  
Phi Pham ◽  
Joseph S. Lam ◽  
Cezar M. Khursigara
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Amino Acid ◽  
Chain Length ◽  
Virulence Factor ◽  
Gram Negative Bacteria ◽  
Gram Negative ◽  
Content Type ◽  
O Antigen ◽  
Chain Lengths ◽  
Insight Into

ABSTRACTThe outer leaflet of the outer membrane of nearly all Gram-negative bacteria contains lipopolysaccharide (LPS). The distal end of LPS may be capped with O antigen, a long polysaccharide that can range from a few to hundreds of sugars in length. The chain length of the polysaccharide has many implications for bacterial survival and consequently is tightly controlled. In the Wzx/Wzy-dependent route of O antigen synthesis, one or more Wzz proteins determine the chain length via an unknown mechanism. To gain insight into this mechanism, we identified and characterized important regions of two Wzz proteins inPseudomonas aeruginosaserotype O13, which confer the production of “long” (Wzz1) and “very long” (Wzz2) chain lengths, respectively. We found that compared to Wzz1, Wzz2has distinct amino acid insertions in the central α-helices (insα6and insα7) and in membrane-distal (insL4) and -proximal (insIL) loops. When these regions were deleted in Wzz2, the mutant proteins conferred drastically shortened chain lengths. Within these regions we identified several conserved amino acid residues that were then targeted for site-directed mutagenesis. Our results implicate an RTE motif in loop 4 and a “hot spot” of charged and polar residues in insα7in the function of Wzz2. We present evidence that the functionally important residues of insα7are likely involved in stabilizing Wzz through coiled-coil interactions.IMPORTANCEO antigen is an important virulence factor presented on the cell surface of Gram-negative bacteria that is critical for bacterial physiology and pathogenesis. However, some aspects of O antigen biosynthesis, such as the mechanisms for determining polysaccharide chain length, are poorly understood. In this study, we identified unique regions in the O antigen chain length regulators (termed Wzz) of the problematic opportunistic pathogenPseudomonas aeruginosa. We show that these regions are critical for determining O antigen chain length, which provides new insight into the model of the Wzz mechanism. Ultimately, our work adds knowledge toward understanding an important step in the biosynthesis of this virulence factor, which is applicable to a wide range of Gram-negative pathogens.

Bacterial-Mucosal Cell Junctional Complexes

1974 ◽  
Vol 32 ◽  
pp. 144-145
Author(s):  
Roger C. Wagner
Keyword(s):  
Intestinal Wall ◽  
Rat Colon ◽  
Mucosal Cell ◽  
Gram Negative Bacteria ◽  
Gram Negative ◽  
Mucosal Cells ◽  
Mucosal Lining ◽  
Degenerative Alterations ◽  
Junctional Complexes ◽  
Intestinal Mucosal Cells

Bacteria exhibit the ability to adhere to the apical surfaces of intestinal mucosal cells. These attachments either precede invasion of the intestinal wall by the bacteria with accompanying inflammation and degeneration of the mucosa or represent permanent anchoring sites where the bacteria never totally penetrate the mucosal cells.Endemic gram negative bacteria were found attached to the surface of mucosal cells lining the walls of crypts in the rat colon. The bacteria did not intrude deeper than 0.5 urn into the mucosal cells and no degenerative alterations were detectable in the mucosal lining.

Rapid demonstration of septic or infectious arthritis due to Gram-negative bacteria

1992 ◽  
Vol 50 (1) ◽  
pp. 686-687
Author(s):  
Jacob S. Hanker ◽  
Paul R. Gross ◽  
Beverly L. Giammara
Keyword(s):  
Chronic Arthritis ◽  
Blood Cultures ◽  
Gram Negative Bacteria ◽  
Infectious Arthritis ◽  
Bacterial Arthritis ◽  
Gram Positive ◽  
Gram Negative ◽  
Gram Positive Bacteria

Blood cultures are positive in approximately only 50 per cent of the patients with nongonococcal bacterial infectious arthritis and about 20 per cent of those with gonococcal arthritis. But the concept that gram-negative bacteria could be involved even in chronic arthritis is well-supported. Gram stains are more definitive in staphylococcal arthritis caused by gram-positive bacteria than in bacterial arthritis due to gram-negative bacteria. In the latter situation where gram-negative bacilli are the problem, Gram stains are helpful for 50% of the patients; they are only helpful for 25% of the patients, however, where gram-negative gonococci are the problem. In arthritis due to gram-positive Staphylococci. Gramstained smears are positive for 75% of the patients.

Ultrastructure of periplasmic bodies in gram-negative bacteria

1990 ◽  
Vol 48 (3) ◽  
pp. 640-641
Author(s):  
Xie Nianming ◽  
Ding Shaoqing ◽  
Wang Luping ◽  
Yuan Zenglin ◽  
Zhan Guolai ◽  
...  
Keyword(s):  
Electron Microscope ◽  
Campylobacter Jejuni ◽  
Proteus Mirabilis ◽  
Shigella Flexneri ◽  
Morphological Description ◽  
Gram Negative Bacteria ◽  
Periplasmic Space ◽  
Clostridium Tetani ◽  
Gram Negative ◽  
Brucella Canis

Perhaps the data about periplasmic enzymes are obtained through biochemical methods but lack of morphological description. We have proved the existence of periplasmic bodies by electron microscope and described their ultrastructures. We hope this report may draw the attention of biochemists and mrophologists to collaborate on researches in periplasmic enzymes or periplasmic bodies with each other.One or more independent bodies may be seen in the periplasmic space between outer and inner membranes of Gram-negative bacteria, which we called periplasmic bodies. The periplasmic bodies have been found in seven species of bacteria at least, including the Pseudomonas aeroginosa. Shigella flexneri, Echerichia coli. Yersinia pestis, Campylobacter jejuni, Proteus mirabilis, Clostridium tetani. Vibrio cholerae and Brucella canis.

Dual stain kit for the microscopic gram classification of ocular infection bacteria

1993 ◽  
Vol 51 ◽  
pp. 248-249
Author(s):  
Jacob S. Hanker ◽  
Dale N. Holdren ◽  
Kenneth L. Cohen ◽  
Beverly L. Giammara
Keyword(s):  
Contact Lenses ◽  
Ocular Infection ◽  
Gram Negative Bacteria ◽  
Gram Negative ◽  
Gram Staining ◽  
Ocular Infections ◽  
Different Types ◽  
Culture Positive ◽  
Increased Susceptibility

Keratitis and conjunctivitis (infections of the cornea or conjunctiva) are ocular infections caused by various bacteria, fungi, viruses or parasites; bacteria, however, are usually prominent. Systemic conditions such as alcoholism, diabetes, debilitating disease, AIDS and immunosuppressive therapy can lead to increased susceptibility but trauma and contact lens use are very important factors. Gram-negative bacteria are most frequently cultured in these situations and Pseudomonas aeruginosa is most usually isolated from culture-positive ulcers of patients using contact lenses. Smears for staining can be obtained with a special swab or spatula and Gram staining frequently guides choice of a therapeutic rinse prior to the report of the culture results upon which specific antibiotic therapy is based. In some cases staining of the direct smear may be diagnostic in situations where the culture will not grow. In these cases different types of stains occasionally assist in guiding therapy.

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