scholarly journals Double Knockout Mutants of Arabidopsis Grown under Normal Conditions Reveal that the Plastidial Phosphorylase Isozyme Participates in Transitory Starch Metabolism

2013 ◽  
Vol 164 (2) ◽  
pp. 907-921 ◽  
Author(s):  
Irina Malinova ◽  
Sebastian Mahlow ◽  
Saleh Alseekh ◽  
Tom Orawetz ◽  
Alisdair R. Fernie ◽  
...  
Keyword(s):  
Starch Metabolism ◽  
Double Knockout ◽  
Knockout Mutants ◽  
Transitory Starch

Characterization of CAP1 and ECA4 adaptors participating in clathrin-mediated endocytosis

2022 ◽  
Author(s):  
Maciek Adamowski ◽  
Ivana Matijević ◽  
Jiří Friml
Keyword(s):  
Fluorescent Protein ◽  
Phosphorylation Site ◽  
Large Family ◽  
Adaptor Proteins ◽  
Serine Phosphorylation ◽  
Binding Motif ◽  
Double Knockout ◽  
Coated Pits ◽  
Knockout Mutants ◽  
Golgi Network

Formation of endomembrane vesicles is crucial in all eukaryotic cells and relies on vesicle coats such as clathrin. Clathrin-coated vesicles form at the plasma membrane and the trans-Golgi Network. They contain adaptor proteins, which serve as binding bridges between clathrin, vesicle membranes, and cargoes. A large family of monomeric ANTH/ENTH/VHS adaptors is present in A. thaliana. Here, we characterize two homologous ANTH-type clathrin adaptors, CAP1 and ECA4, in clathrin-mediated endocytosis (CME). CAP1 and ECA4 are recruited to sites at the PM identified as clathrin-coated pits (CCPs), where they occasionally exhibit early bursts of high recruitment. Subcellular binding preferences of N- and C-terminal fluorescent protein fusions of CAP1 identified a functional adaptin-binding motif in the unstructured tails of CAP1 and ECA4. In turn, no function can be ascribed to a double serine phosphorylation site conserved in these proteins. Double knockout mutants do not exhibit deficiencies in general development or CME, but a contribution of CAP1 and ECA4 to these processes is revealed in crosses into sensitized endocytic mutant backgrounds. Overall, our study documents a contribution of CAP1 and ECA4 to CME in A. thaliana and opens questions about functional redundancy among non-homologous vesicle coat components.

scholarly journals Attenuation of Salmonella enterica Serovar Typhimurium by Altering Biological Functions of Murein Lipoprotein and Lipopolysaccharide

2005 ◽  
Vol 73 (12) ◽  
pp. 8433-8436 ◽  
Author(s):  
A. A. Fadl ◽  
J. Sha ◽  
G. R. Klimpel ◽  
J. P. Olano ◽  
C. L. Galindo ◽  
...  
Keyword(s):  
Salmonella Enterica ◽  
Salmonella Enterica Serovar Typhimurium ◽  
Biological Functions ◽  
Double Knockout ◽  
In Vivo Models ◽  
Background Strain ◽  
Knockout Mutants ◽  
Serovar Typhimurium

ABSTRACT We constructed Salmonella enterica serovar Typhimurium double-knockout mutants in which either the lipoprotein A (lppA) or the lipoprotein B (lppB) gene was deleted from an msbB-negative background strain by marker exchange mutagenesis. These mutants were highly attenuated when tested with in vitro and in vivo models of Salmonella pathogenesis.

scholarly journals Two DHH Subfamily 1 Proteins Contribute to Pneumococcal Virulence and Confer Protection against Pneumococcal Disease

2011 ◽  
Vol 79 (9) ◽  
pp. 3697-3710 ◽  
Author(s):  
L. E. Cron ◽  
K. Stol ◽  
P. Burghout ◽  
S. van Selm ◽  
E. R. Simonetti ◽  
...  
Keyword(s):  
Otitis Media ◽  
Pneumococcal Disease ◽  
Capsular Polysaccharide ◽  
Pneumococcal Infection ◽  
Bacterial Pathogen ◽  
Protein Vaccine ◽  
Double Knockout ◽  
Content Type ◽  
Knockout Mutants ◽  
Different Strains

ABSTRACTStreptococcus pneumoniaeis an important human bacterial pathogen, causing such infections as pneumonia, meningitis, septicemia, and otitis media. Current capsular polysaccharide-based conjugate vaccines protect against a fraction of the over 90 serotypes known, whereas vaccines based on conserved pneumococcal proteins are considered promising broad-range alternatives. The pneumococcal genome encodes two conserved proteins of an as yet unknown function, SP1298 and SP2205, classified as DHH (Asp-His-His) subfamily 1 proteins. Here we examined their contribution to pneumococcal pathogenesis using single and double knockout mutants in three different strains: D39, TIGR4, and BHN100. Mutants lacking both SP1298 and SP2205 were severely impaired in adherence to human epithelial Detroit 562 cells. Importantly, the attenuated phenotypes were restored upon genetic complementation of the deleted genes. Single and mixed mouse models of colonization, otitis media, pneumonia, and bacteremia showed that bacterial loads in the nasopharynx, middle ears, lungs, and blood of mice infected with the mutants were significantly reduced from those of wild-type-infected mice, with an apparent additive effect upon deletion of both genes. Minor strain-specific phenotypes were observed, i.e., deletion of SP1298 affected host-cell adherence in BHN100 only, and deletion of SP2205 significantly attenuated virulence in lungs and blood in D39 and BHN100 but not TIGR4. Finally, subcutaneous vaccination with a combination of both DHH subfamily 1 proteins conferred protection to nasopharynx, lungs, and blood of mice infected with TIGR4. We conclude that SP1298 and SP2205 play a significant role at several stages of pneumococcal infection, and importantly, these proteins are potential candidates for a multicomponent protein vaccine.

scholarly journals A Helicobacter pylori TolC Efflux Pump Confers Resistance to Metronidazole

2005 ◽  
Vol 49 (4) ◽  
pp. 1477-1482 ◽  
Author(s):  
Karin van Amsterdam ◽  
Aldert Bart ◽  
Arie van der Ende
Keyword(s):  
Helicobacter Pylori ◽  
Efflux Pump ◽  
Sodium Deoxycholate ◽  
Loss Of Function ◽  
Knockout Mutant ◽  
Double Knockout ◽  
Active Efflux ◽  
Knockout Mutants ◽  
H Pylori ◽  
Susceptibility Profiles

ABSTRACT In Helicobacter pylori, the contribution of efflux proteins to antibiotic resistance is not well established. As translocases that act in parallel may have overlapping substrate specificities, the loss of function of one such translocase may be compensated for by that of another translocase with no effect on susceptibilities to antibiotics. The genome of H. pylori 26695 was assessed for the presence of putative translocases and outer membrane efflux or TolC-like proteins which could interact to form efflux systems involved in drug resistance. Twenty-seven translocases were identified, of which HP1184 was the sole representative of the multidrug and toxic compound extrusion family of translocases and which could thus have a unique substrate specificity. In addition, four TolC-like proteins (HP0605, HP0971, HP1327, and HP1489) were identified. Thus, it is feasible that inactivation of a TolC-like protein would affect the functions of multiple translocases. We aimed to determine whether efflux systems contribute to antimicrobial susceptibility by evaluation of the susceptibility profiles of an HP1184-knockout mutant, four mutants in which one of the four TolC homologs was inactivated, as well as a mutant in which both HP0605 and HP0971 were inactivated. The HP1184- and HP1489-knockout mutants both showed increased susceptibilities to ethidium bromide, while the HP0605-knockout mutant exhibited increased susceptibilities to novobiocin and sodium deoxycholate. The HP0605 and HP0971 double-knockout mutant was also more susceptible to metronidazole, in addition to being susceptible to novobiocin and sodium deoxycholate. Thus, active efflux is an eminent means of resistance to antimicrobials in H. pylori and resembles the situation in other bacteria.

scholarly journals Isolation and Analysis of Donor Chromosomal Genes Whose Deficiency Is Responsible for Accelerating Bacterial and Trans-Kingdom Conjugations by IncP1 T4SS Machinery

2021 ◽  
Vol 12 ◽  
Author(s):  
Fatin Iffah Rasyiqah Mohamad Zoolkefli ◽  
Kazuki Moriguchi ◽  
Yunjae Cho ◽  
Kazuya Kiyokawa ◽  
Shinji Yamamoto ◽  
...  
Keyword(s):  
Host Range ◽  
Gene Knockout ◽  
Synergistic Effects ◽  
Conjugal Transfer ◽  
Homologous Gene ◽  
Broad Host Range ◽  
Double Knockout ◽  
E Coli ◽  
Knockout Mutants ◽  
A Genome

Conjugal transfer is a major driving force of genetic exchange in eubacteria, and the system in IncP1-type broad-host-range plasmids transfers DNA even to eukaryotes and archaea in a process known as trans-kingdom conjugation (TKC). Although conjugation factors encoded on plasmids have been extensively analyzed, those on the donor chromosome have not. To identify the potential conjugation factor(s), a genome-wide survey on a comprehensive collection of Escherichia coli gene knockout mutants (Keio collection) as donors to Saccharomyces cerevisiae recipients was performed using a conjugal transfer system mediated by the type IV secretion system (T4SS) of the IncP1α plasmid. Out of 3,884 mutants, three mutants (ΔfrmR, ΔsufA, and ΔiscA) were isolated, which showed an increase by one order of magnitude in both E. coli–E. coli and E. coli–yeast conjugations without an increase in the mRNA accumulation level for the conjugation related genes examined. The double-knockout mutants for these genes (ΔfrmRΔsufA and ΔiscAΔfrmR) did not show synergistic effects on the conjugation efficiency, suggesting that these factors affect a common step in the conjugation machinery. The three mutants demonstrated increased conjugation efficiency in IncP1β-type but not in IncN- and IncW-type broad-host-range plasmid transfers, and the homologous gene knockout mutants against the three genes in Agrobacterium tumefaciens also showed increased TKC efficiency. These results suggest the existence of a specific regulatory system in IncP1 plasmids that enables the control of conjugation efficiency in different hosts, which could be utilized for the development of donor strains as gene introduction tools into bacteria, eukaryotes, and archaea.

Developmental defects and seedling lethality in apyrase AtAPY1 and AtAPY2 double knockout mutants

2007 ◽  
Vol 64 (6) ◽  
pp. 657-672 ◽  
Author(s):  
Carolin Wolf ◽  
Maria Hennig ◽  
Dwight Romanovicz ◽  
Iris Steinebrunner
Keyword(s):  
Double Knockout ◽  
Developmental Defects ◽  
Knockout Mutants ◽  
Seedling Lethality

scholarly journals Major Role of NAD-Dependent Lactate Dehydrogenases in Aerobic Lactate Utilization in Lactobacillus plantarum during Early Stationary Phase

2004 ◽  
Vol 186 (19) ◽  
pp. 6661-6666 ◽  
Author(s):  
Philippe Goffin ◽  
Frédérique Lorquet ◽  
Michiel Kleerebezem ◽  
Pascal Hols
Keyword(s):  
Lactate Dehydrogenase ◽  
Stationary Phase ◽  
Lactobacillus Plantarum ◽  
Aerobic Growth ◽  
Early Stationary Phase ◽  
Double Knockout ◽  
Knockout Mutants ◽  
Lactate Utilization ◽  
Lactate Dehydrogenases

ABSTRACT NAD-independent lactate dehydrogenases are commonly thought to be responsible for lactate utilization during the stationary phase of aerobic growth in Lactobacillus plantarum. To substantiate this view, we constructed single and double knockout mutants for the corresponding genes, loxD and loxL. Lactate-to-acetate conversion was not impaired in these strains, while it was completely blocked in mutants deficient in NAD-dependent lactate dehydrogenase activities, encoded by the ldhD and ldhL genes. We conclude that NAD-dependent but not NAD-independent lactate dehydrogenases are involved in this process.

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