scholarly journals Functional characterisation of substrate-binding proteins to address nutrient uptake in marine picocyanobacteria

2021 ◽  
Author(s):  
Benjamin A. Ford ◽  
Geraldine J. Sullivan ◽  
Lisa Moore ◽  
Deepa Varkey ◽  
Hannah Zhu ◽  
...  
Keyword(s):  
Nutrient Uptake ◽  
Abc Transporters ◽  
Substrate Binding ◽  
Transport Systems ◽  
Receptor Protein ◽  
Abc Transport ◽  
Functional Characterisation ◽  
Large Numbers ◽  
Nutrient Profiles ◽  
Almost All

Marine cyanobacteria are key primary producers, contributing significantly to the microbial food web and biogeochemical cycles by releasing and importing many essential nutrients cycled through the environment. A subgroup of these, the picocyanobacteria (Synechococcus and Prochlorococcus), have colonised almost all marine ecosystems, covering a range of distinct light and temperature conditions, and nutrient profiles. The intra-clade diversities displayed by this monophyletic branch of cyanobacteria is indicative of their success across a broad range of environments. Part of this diversity is due to nutrient acquisition mechanisms, such as the use of high-affinity ATP-binding cassette (ABC) transporters to competitively acquire nutrients, particularly in oligotrophic (nutrient scarce) marine environments. The specificity of nutrient uptake in ABC transporters is primarily determined by the peripheral substrate-binding protein (SBP), a receptor protein that mediates ligand recognition and initiates translocation into the cell. The recent availability of large numbers of sequenced picocyanobacterial genomes indicates both Synechococcus and Prochlorococcus apportion >50% of their transport capacity to ABC transport systems. However, the low degree of sequence homology among the SBP family limits the reliability of functional assignments using sequence annotation and prediction tools. This review highlights the use of known SBP structural representatives for the uptake of key nutrient classes by cyanobacteria to compare with predicted SBP functionalities within sequenced marine picocyanobacteria genomes. This review shows the broad range of conserved biochemical functions of picocyanobacteria and the range of novel and hypothetical ABC transport systems that require further functional characterisation.

A structural and functional analysis of type III periplasmic and substrate binding proteins: their role in bacterial siderophore and heme transport

2011 ◽  
Vol 392 (1-2) ◽  
Author(s):  
Byron C.H. Chu ◽  
Hans J. Vogel
Keyword(s):  
Binding Proteins ◽  
Substrate Binding ◽  
Transport Systems ◽  
Complex Structures ◽  
Type Iii ◽  
Heme Transport ◽  
Periplasmic Binding Proteins ◽  
Outer Membrane Transporter ◽  
Α Helix ◽  
Carboxy Terminal

AbstractInEscherichia colithe Fhu, Fep and Fec transport systems are involved in the uptake of chelated ferric iron-siderophore complexes, whereas in pathogenic strains heme can also be used as an iron source. An essential step in these pathways is the movement of the ferric-siderophore complex or heme from the outer membrane transporter across the periplasm to the cognate cytoplasmic membrane ATP-dependent transporter. This is accomplished in each case by a dedicated periplasmic binding protein (PBP). Ferric-siderophore binding PBPs belong to the PBP protein superfamily and adopt a bilobal type III structural fold in which the two independently folded amino and carboxy terminal domains are linked together by a single long α-helix of approximately 20 amino acids. Recent structural studies reveal how the PBPs of the Fhu, Fep, Fec and Chu systems are able to bind their corresponding ligands. These complex structures will be discussed and placed in the context of our current understanding of the entire type III family of Gram-negative periplasmic binding proteins and related Gram-positive substrate binding proteins.

scholarly journals A Molecular Basis for Tungstate Selectivity in Prokaryotic ABC Transport Systems

2011 ◽  
Vol 193 (18) ◽  
pp. 4999-5001 ◽  
Author(s):  
L. E. Bevers ◽  
G. Schwarz ◽  
W. R. Hagen
Keyword(s):  
Molecular Basis ◽  
Transport Systems ◽  
Abc Transport

Host-mediated RNAi of a Notch-like receptor gene inMeloidogyne incognitainduces nematode resistance

Parasitology ◽  
2018 ◽  
Vol 145 (14) ◽  
pp. 1896-1906
Author(s):  
Deshika Kohli ◽  
Parameswaran Chidambaranathan ◽  
J. Prasanth Tej Kumar ◽  
Ashish Kumar Singh ◽  
Anil Kumar ◽  
...  
Keyword(s):  
Transmembrane Domain ◽  
Receptor Gene ◽  
Nematode Resistance ◽  
Receptor Protein ◽  
Binding Motifs ◽  
C Elegans ◽  
Transgenic Lines ◽  
Germline Proliferation ◽  
Epidermal Growth ◽  
Almost All

AbstractGLP-1 (abnormal germline proliferation) is a Notch-like receptor protein that plays an essential role in pharyngeal development. In this study, an orthologue ofCaenorhabditis elegans glp-1was identified inMeloidogyne incognita. A computational analysis revealed that the orthologue contained almost all the domains present in theC. elegansgene: specifically, the LIN-12/Notch repeat, the ankyrin repeat, a transmembrane domain and different ligand-binding motifs were present in orthologue, but the epidermal growth factor-like motif was not observed. An expression analysis showed differential expression ofglp-1throughout the life cycle ofM. incognita, with relatively higher expression in the egg stage. To evaluate the silencing efficacy ofMi-glp-1, transgenicArabidopsisplants carrying double-stranded RNA constructs ofglp-1were generated, and infection of these plants withM. incognitaresulted in a 47–50% reduction in the numbers of galls, females and egg masses. Females obtained from the transgenic RNAi lines exhibited 40–60% reductions in the transcript levels of the targetedglp-1gene compared with females isolated from the control plants. Second-generation juveniles (J2s), which were descendants of the infected females from the transgenic lines, showed aberrant phenotypes. These J2s exhibited a significant decrease in the overall distance from the stylet to the metacorpus region, and this effect was accompanied by disruption around the metacorporeal bulb of the pharynx. The present study suggests a role for this gene in organ (pharynx) development during embryogenesis inM. incognitaand its potential use as a target in the management of nematode infestations in plants.

scholarly journals The number of bacilli harboured by enteric carriers

1954 ◽  
Vol 52 (1) ◽  
pp. 67-70 ◽  
Author(s):  
Scott Thomson
Keyword(s):  
Pure Culture ◽  
Medical Officer ◽  
Salmonella Typhi ◽  
Enrichment Medium ◽  
Mental Hospitals ◽  
Culture Plate ◽  
Large Numbers ◽  
Paratyphi B ◽  
Almost All

Salmonella typhi or S. paratyphi B were found in very large numbers in the faeces of enteric carriers. Of twenty-four carriers, four were found negative by the fullest examination. Of the twenty found positive almost all harboured many millions of bacilli per gram of faeces.A minute inoculum of one drop (1/50 ml.) of a 1:1000 dilution of faeces on a culture plate only rarely failed to reveal all the positives without the use of an ‘enrichment’ medium and the result of such a procedure was a culture plate with virtually a pure culture of the pathogen.I am grateful to the Medical Superintendents of the Mental Hospitals at Cardiff, Bridgend and Denbigh, and the Medical Officer of Health for Brecon for submitting specimens for examination.

A discussion on ship technology in the 1980s - Shipyards of the future: possibilities and prospects

1972 ◽  
Vol 273 (1231) ◽  
pp. 173-181
Keyword(s):  
Social Influence ◽  
Ship Design ◽  
Transport Systems ◽  
Trade Patterns ◽  
Large Numbers ◽  
The Social ◽  
The Future ◽  
High Level ◽  
Investment Patterns ◽  
Trade And Investment

Some comments are made on the effect of world trends, economic and social influence on future trade and investment patterns, and the growing influence of the emergent nations. The attractions of shipbuilding as an employer of large numbers, embodying a high level of technology and its national value are reviewed. Developments in transport systems and the future of ships as the main form of bulk transport are discussed, together with some of the considerations and restrictions which may affect ship design in the future. The trend towards specialized ship types is reviewed. The siting and design of future shipyards is discussed in the light of advances in technology. Consideration will be given to the changes in trade patterns and transport systems and their influence on shipyards. Mention will be made of the social and economic facets involved in the choice of the site and the design of the shipyard.

A Dispersal of Larvae of the Colorado Potato Beetle, Leptinotarsa decemlineata (Say) (Coleoptera: Chrysomelidae)

1957 ◽  
Vol 89 (12) ◽  
pp. 581-582 ◽  
Author(s):  
L. M. Cass
Keyword(s):  
Plant Resistance ◽  
Colorado Potato Beetle ◽  
Leptinotarsa Decemlineata ◽  
Large Scale ◽  
Potato Beetle ◽  
Large Numbers ◽  
Leptinotarsa Decemlineata Say ◽  
The One ◽  
Almost All

In July, 1952, during studies on the Colorado potato beetle, Leptinotarsa decemlineata (Say), at Merivale, Ontario, a large-scale dispersal of the larvae was observed. A field of early potatoes consisting of seven 100-foot rows, which was to be used as a source of supply of the insect for plant resistance studies, had been artifically infested on June 30 by placing an overwintered adult on each plant. The beetles laid eggs in largc numbers and by the second week of July the plants were overpopulated wit11 larvae. By July 14 the plants were stripped of foliage and the larvae were forced to feed on the stalks. On the morning of July 16 the starving larvae began to leave the plants in large numbers. Almost all left on the one day, some of them travelling considerable distances.

scholarly journals ATP-binding Cassette Transporters Are Required for Efficient RNA Interference in Caenorhabditis elegans

2006 ◽  
Vol 17 (8) ◽  
pp. 3678-3688 ◽  
Author(s):  
Prema Sundaram ◽  
Benjamin Echalier ◽  
Wang Han ◽  
Dawn Hull ◽  
Lisa Timmons
Keyword(s):  
Rna Interference ◽  
Caenorhabditis Elegans ◽  
Abc Transporters ◽  
Transport Systems ◽  
Atp Binding ◽  
C Elegans ◽  
Steep Concentration Gradient ◽  
Conserved Gene ◽  
Membrane Transport Systems ◽  
Atp Binding Cassette

RNA interference (RNAi) is a conserved gene-silencing phenomenon that can be triggered by delivery of double-stranded RNA (dsRNA) to cells and is a widely exploited technology in analyses of gene function. Although a number of proteins that facilitate RNAi have been identified, current descriptions of RNAi and interrelated mechanisms are far from complete. Here, we report that the Caenorhabditis elegans gene haf-6 is required for efficient RNAi. HAF-6 is a member of the ATP-binding cassette (ABC) transporter gene superfamily. ABC transporters use ATP to translocate small molecule substrates across the membranes in which they reside, often against a steep concentration gradient. Collectively, ABC transporters are involved in a variety of activities, including protective or barrier mechanisms that export drugs or toxins from cells, organellar biogenesis, and mechanisms that protect against viral infection. HAF-6 is expressed predominantly in the intestine and germline and is localized to intracellular reticular organelles. We further demonstrate that eight additional ABC genes from diverse subfamilies are each required for efficient RNAi in C. elegans. Thus, the ability to mount a robust RNAi response to dsRNA depends upon the deployment of two ancient systems that respond to environmental assaults: RNAi mechanisms and membrane transport systems that use ABC proteins.

Pollination services provided by various size classes of flower visitors to Eucalyptus globulus ssp. globulus (Myrtaceae)

2004 ◽  
Vol 52 (3) ◽  
pp. 353 ◽  
Author(s):  
A. B. Hingston ◽  
B. M. Potts ◽  
P. B. McQuillan
Keyword(s):  
Seed Production ◽  
Eucalyptus Globulus ◽  
Seed Set ◽  
Pollen Limitation ◽  
Pollination Services ◽  
Flower Visitors ◽  
Large Numbers ◽  
Introduced Honeybee ◽  
Commercially Important ◽  
Almost All

Flowers of the commercially important tree Eucalyptus globulus Labill. ssp. globulus were visited by a wide variety of insects and birds within its natural distribution. Flowers were visited so frequently that most available nectar was consumed, but seed production within 5 m of the ground was consistently far less than the maximum possible, indicating the presence of large numbers of inefficient pollinators and few efficient pollinators. Pollen limitation was more severe on fully self-incompatible trees than on partially self-compatible trees, demonstrating that pollinator inefficiency resulted from infrequent outcrossing rather than inability to deposit pollen on stigmas. The flower visitors that were responsible for almost all nectar consumption from flowers within 5 m of the ground were insects that were able to permeate cages with 5-mm apertures but not cages with 1-mm apertures, the most abundant of which was the introduced honeybee Apis mellifera L. These insects contributed less than 20% of the maximum possible seed set, indicating that they were inefficient pollinators. Birds and smaller insects made lesser contributions to seed production, but consumed little nectar within 5 m of the ground. However, anthophilous birds appeared to mostly forage higher in the trees and probably consumed more nectar from, and provided more pollination services to, flowers higher in the trees.

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