Dependence of the superficial layers of Spirillum putridiconchylium on Ca2+ or Sr2+

1976 ◽  
Vol 22 (9) ◽  
pp. 1233-1244 ◽  
Author(s):  
T. J. Beveridge ◽  
R. G. E. Murray
Keyword(s):  
Cell Surface ◽  
Outer Membrane ◽  
Growth Medium ◽  
Chelating Agents ◽  
Membrane Surface ◽  
Superficial Layer ◽  
Cationized Ferritin ◽  
Membrane Component ◽  
Casamino Acids ◽  
Amorphous Precipitate

Chelating agents disrupted the superficial layers on Spirillum putridiconchylium and adsorption of cationized ferritin indicated that both upper and lower surfaces of superficial layer fragments, as well as the outer membrane surface, possessed areas which were negatively charged. Growth of the bacterium in 1% casamino acids (vitamin free) resulted in cells which were devoid of the superficial layers, and negative staining of these cells revealed an amorphous precipitate together with a vesicular outer membrane component extruding from their surfaces into the medium. Addition of either 1 mM Ca2+ or 1 mM Sr2+ to the growth medium produced the typical regularly structured cell surface, whereas addition of equal concentrations of Li+, Na+, K+, Mg2+, Ba2+, Mn2+, Fe3+, or three polyamines produced the structureless surface.

scholarly journals Nanoscale Visualization of a Fibrillar Array in the Cell Wall of Filamentous Cyanobacteria and Its Implications for Gliding Motility

2007 ◽  
Vol 189 (20) ◽  
pp. 7361-7366 ◽  
Author(s):  
Nicholas Read ◽  
Simon Connell ◽  
David G. Adams
Keyword(s):  
Cell Surface ◽  
Outer Membrane ◽  
Membrane Surface ◽  
Gliding Motility ◽  
Filamentous Cyanobacteria ◽  
Membrane Surface Area ◽  
Force Microscopy ◽  
Atomic Force ◽  
Generate Surface ◽  
Alternative Function

ABSTRACT Many filamentous cyanobacteria are motile by gliding, which requires attachment to a surface. There are two main theories to explain the mechanism of gliding. According to the first, the filament is pushed forward by small waves that pass along the cell surface. In the second, gliding is powered by the extrusion of slime through pores surrounding each cell septum. We have previously shown that the cell walls of several motile cyanobacteria possess an array of parallel fibrils between the peptidoglycan and the outer membrane and have speculated that the function of this array may be to generate surface waves to power gliding. Here, we report on a study of the cell surface topography of two morphologically different filamentous cyanobacteria, using field emission gun scanning electron microscopy (FEGSEM) and atomic force microscopy (AFM). FEGSEM and AFM images of Oscillatoria sp. strain A2 confirmed the presence of an array of fibrils, visible as parallel corrugations on the cell surface. These corrugations were also visualized by AFM scanning of fully hydrated filaments under liquid; this has not been achieved before for filamentous bacteria. FEGSEM images of Nostoc punctiforme revealed a highly convoluted, not parallel, fibrillar array. We conclude that an array of parallel fibrils, beneath the outer membrane of Oscillatoria, may function in the generation of thrust in gliding motility. The array of convoluted fibrils in N. punctiforme may have an alternative function, perhaps connected with the increase in outer membrane surface area resulting from the presence of the fibrils.

scholarly journals Burkholderia collagen-like protein 8, Bucl8, is a unique outer membrane component of a tetrapartite efflux pump in Burkholderia pseudomallei and Burkholderia mallei

2020 ◽  
Author(s):  
Megan E Grund ◽  
Soo J Choi ◽  
Dudley H McNitt ◽  
Mariette Barbier ◽  
Gangqing Hu ◽  
...  
Keyword(s):  
Outer Membrane ◽  
Burkholderia Pseudomallei ◽  
Triple Helix ◽  
Efflux Pump ◽  
Fusaric Acid ◽  
Efflux Pumps ◽  
Resistant Bacteria ◽  
Burkholderia Mallei ◽  
Membrane Component ◽  
Collagen Triple Helix

AbstractBacterial efflux pumps are an important pathogenicity trait because they extrude a variety of xenobiotics. Our laboratory previously identified in silico Burkholderia collagen-like protein 8 (Bucl8) in the Tier one select agents Burkholderia pseudomallei and Burkholderia mallei. We hypothesize that Bucl8, which contains two predicted tandem outer membrane efflux pump domains, is a component of a putative efflux pump. Unique to Bucl8, as compared to other outer membrane proteins, is the presence of an extended extracellular region containing a collagen-like (CL) domain and a non-collagenous C-terminus (Ct). Molecular modeling and circular dichroism spectroscopy with a recombinant protein, corresponding to this extracellular CL-Ct portion of Bucl8, demonstrated that it adopts a collagen triple helix, whereas functional assays screening for Bucl8 ligands identified binding to fibrinogen. Bioinformatic analysis of the bucl8 gene locus revealed it resembles a classical efflux-pump operon. The bucl8 gene is co-localized with downstream fusCDE genes encoding fusaric acid (FA) resistance, and with an upstream gene, designated as fusR, encoding a LysR-type transcriptional regulator. Using RT-qPCR, we defined the boundaries and transcriptional organization of the fusR-bucl8-fusCDE operon. We found exogenous FA induced bucl8 transcription over 80-fold in B. pseudomallei, while deletion of the entire bucl8 locus decreased the MIC of FA 4-fold in its isogenic mutant. We furthermore showed that the Bucl8 pump expressed in the heterologous Escherichia coli host confers FA resistance. On the contrary, the Bucl8 pump did not confer resistance to a panel of clinically-relevant antimicrobials in Burkholderia and E. coli. We finally demonstrated that deletion of the bucl8-locus drastically affects the growth of the mutant in L-broth. We determined that Bucl8 is a component of a novel tetrapartite efflux pump, which confers FA resistance, fibrinogen binding, and optimal growth.Author SummaryBurkholderia pseudomallei and Burkholderia mallei are highly infectious and multidrug resistant bacteria that are classified by the National Institute of Allergy and Infectious Diseases as Tier one select agents partly due to the intrinsic multidrug resistance associated with expression of the efflux pumps. To date, only few efflux pumps predicted in Burkholderia spp. have been studied in detail. In the current study we introduce Bucl8, an outer membrane component of an unreported putative efflux pump with a unique extended extracellular portion that forms a collagen triple helix and binds fibrinogen. We demonstrate Bucl8’s role in fusaric acid resistance by defining its operon via bioinformatic and transcriptional analyses, as well as by employing loss-of-function and gain-of-function genetic approaches. Our studies also implicate the Bucl8-associated pump in metabolic and physiologic homeostasis. Understanding how Bucl8 efflux pump contributes to Burkholderia pathology will foster development of pump inhibitors targeting transport mechanism or identifying potential surface-exposed vaccine targets.

scholarly journals THE EFFECT OF TEMPERATURE AND OF LYSIN CONCENTRATION ON THE ACCELERATION OF HEMOLYSIS

1941 ◽  
Vol 25 (2) ◽  
pp. 247-261
Author(s):  
Eric Ponder
Keyword(s):  
Cell Surface ◽  
Quantitative Description ◽  
Negative Temperature ◽  
Effect Of Temperature ◽  
Membrane Component ◽  
Temperature Coefficients ◽  
Rate Of Escape ◽  
Point To Point ◽  
Special Case ◽  
Do So

The acceleration of saponin hemolysis by benzene, indol, and nonyl alcohol has been investigated as a function of temperature, and it has been found that these accelerators have negative temperature coefficients. This points to their being concentrated at the cell surface, and to the surface being the seat of their accelerating action. It is shown that the accelerating power of indol (used as a typical accelerator) is constant so long as the lysin in the system is capable of producing lysis per se, but that the acceleration falls off when only sublytic concentrations are present. The relations are expressed in a series of equations, and explained in terms of the reactions among the accelerator, the lysin, and the membrane component, which breaks down in spots, rather than uniformly, when lysis occurs. The argument involves a consideration of the idea that a monolayer of lysin at the cell surface is necessary for hemolysis, of Abramson's hypothesis of "key spots" on the surface, of the rate of escape of hemoglobin from the hemolyzing cell, and of the results of electrophoretic and impedance measurements. The existing theory of the kinetics is extended by introducing the idea of a variation in resistance from point to point in the cell membrane; in this form it describes the situation so far as is at present known, and shows that the results of the various methods of investigation are consistent with each other. The only idea discussed which seems to have little foundation is that lysis is determined by the formation of a monolayer of lysin at the cell surface; when this occurs, it must do so only as a special case. Finally, a semi-quantitative description of the frequency distribution of the resistances in the membrane is derived from existing data. The variation in resistance which it is necessary to assume is quite small, as might be expected in the case of a membrane with a regular ultra-structure.

scholarly journals Cell Surface Engineering of a β-Galactosidase for Galactooligosaccharide Synthesis

2009 ◽  
Vol 75 (18) ◽  
pp. 5938-5942 ◽  
Author(s):  
Yumei Li ◽  
Lili Lu ◽  
Hongmei Wang ◽  
Xiaodong Xu ◽  
Min Xiao
Keyword(s):  
Cell Surface ◽  
Surface Engineering ◽  
Yeast Cells ◽  
Penicillium Expansum ◽  
Yeast Nitrogen Base ◽  
Gene Encoding ◽  
Nitrogen Base ◽  
Reading Frame ◽  
Acid Protein ◽  
Casamino Acids

ABSTRACT A novel gene encoding transglycosylating β-galactosidase (BGase) was cloned from Penicillium expansum F3. The sequence contained a 3,036-bp open reading frame encoding a 1,011-amino-acid protein. This gene was subsequently expressed on the cell surface of Saccharomyces cerevisiae EBY-100 by galactose induction. The BGase-anchored yeast could directly utilize lactose to produce galactooligosaccharide (GOS), as well as the by-products glucose and a small quantity of galactose. The glucose was consumed by the yeast, and the galactose was used for BGase expression, thus greatly facilitating GOS synthesis. The GOS yield reached 43.64% when the recombinant yeast was cultivated in yeast nitrogen base-Casamino Acids medium containing 100 g/liter initial lactose at 25°C for 5 days. The yeast cells were harvested and recycled for the next batch of GOS synthesis. During sequential operations, both oligosaccharide synthesis and BGase expression were maintained at high levels with GOS yields of over 40%, and approximately 8 U/ml of BGase was detected in each batch.

scholarly journals Cell Surface Filaments of the Gliding Bacterium Flavobacterium johnsoniae Revealed by Cryo-Electron Tomography

2007 ◽  
Vol 189 (20) ◽  
pp. 7503-7506 ◽  
Author(s):  
Jun Liu ◽  
Mark J. McBride ◽  
Sriram Subramaniam
Keyword(s):  
Cell Surface ◽  
Outer Membrane ◽  
Electron Tomography ◽  
Wild Type ◽  
Unknown Mechanism ◽  
Flavobacterium Johnsoniae ◽  
Atp Binding Cassette Transporter ◽  
Cryo Electron Tomography ◽  
Inner Surface ◽  
Gliding Bacterium

ABSTRACT Flavobacterium johnsoniae cells glide rapidly over surfaces by an as-yet-unknown mechanism. Using cryo-electron tomography, we show that wild-type cells display tufts of ∼5-nm-wide cell surface filaments that appear to be anchored to the inner surface of the outer membrane. These filaments are absent in cells of a nonmotile gldF mutant but are restored upon expression of plasmid-encoded GldF, a component of a putative ATP-binding cassette transporter.

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