scholarly journals 40S ribosome profiling reveals distinct roles for Tma20/Tma22 (MCT-1/DENR) and Tma64 (eIF2D) in 40S subunit recycling

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
David J. Young ◽  
Sezen Meydan ◽  
Nicholas R. Guydosh
Keyword(s):  
Protein Synthesis ◽  
Neurological Disease ◽  
Ribosome Profiling ◽  
Minor Role ◽  
Stop Codons ◽  
Genes Encoding ◽  
Ribosome Footprinting ◽  
A Minor ◽  
And Control ◽  
In Cells

AbstractThe recycling of ribosomes at stop codons for use in further rounds of translation is critical for efficient protein synthesis. Removal of the 60S subunit is catalyzed by the ATPase Rli1 (ABCE1) while removal of the 40S is thought to require Tma64 (eIF2D), Tma20 (MCT-1), and Tma22 (DENR). However, it remains unclear how these Tma proteins cause 40S removal and control reinitiation of downstream translation. Here we used a 40S ribosome footprinting strategy to directly observe intermediate steps of ribosome recycling in cells. Deletion of the genes encoding these Tma proteins resulted in broad accumulation of unrecycled 40S subunits at stop codons, directly establishing their role in 40S recycling. Furthermore, the Tma20/Tma22 heterodimer was responsible for a majority of 40S recycling events while Tma64 played a minor role. Introduction of an autism-associated mutation into TMA22 resulted in a loss of 40S recycling activity, linking ribosome recycling and neurological disease.

scholarly journals Diversity, Epidemiology, and Genetics of Class D β-Lactamases

2009 ◽  
Vol 54 (1) ◽  
pp. 24-38 ◽  
Author(s):  
Laurent Poirel ◽  
Thierry Naas ◽  
Patrice Nordmann
Keyword(s):  
Natural Resistance ◽  
Minor Role ◽  
Insertion Sequences ◽  
Class 1 Integron ◽  
Gram Negative ◽  
Class D ◽  
Class 1 ◽  
Great Heterogeneity ◽  
Genes Encoding ◽  
A Minor

ABSTRACT Class D β-lactamase-mediated resistance to β-lactams has been increasingly reported during the last decade. Those enzymes also known as oxacillinases or OXAs are widely distributed among Gram negatives. Genes encoding class D β-lactamases are known to be intrinsic in many Gram-negative rods, including Acinetobacter baumannii and Pseudomonas aeruginosa, but play a minor role in natural resistance phenotypes. The OXAs (ca. 150 variants reported so far) are characterized by an important genetic diversity and a great heterogeneity in terms of β-lactam hydrolysis spectrum. The acquired OXAs possess either a narrow spectrum or an expanded spectrum of hydrolysis, including carbapenems in several instances. Acquired class D β-lactamase genes are mostly associated to class 1 integron or to insertion sequences.

ENCI

1980 ◽  
Vol 22 (4) ◽  
pp. 441-462 ◽  
Author(s):  
Alfred H. Saulniers
Keyword(s):  
Public Sector ◽  
Regional Development ◽  
Minor Role ◽  
Economic Evolution ◽  
Steel Mill ◽  
The Public ◽  
Domestic Trade ◽  
A Minor ◽  
And Control ◽  
State Enterprises

Until 1968, state enterprises played a minor role in the Peruvian economy. The list of public sector enterprises was relatively small. It included the Central and sectoral banks, a merchant fleet, railways, a minor petroleum producer, hyroelectric power companies, a steel mill, monopolies over salt, tobacco, and guano, a few tourism projects, and a set of regional development corporations. From 1968 to 1974 the state moved swiftly to expand its role in order to direct and control the course of the country's economic evolution. The public sector increased both in size and scope to include most banking, basic industries, and most international and some domestic trade.

scholarly journals Relative Contribution of the ABC Transporters Cdr1, Pdh1, and Snq2 to Azole Resistance inCandida glabrata

2018 ◽  
Vol 62 (10) ◽  
Author(s):  
Sarah G. Whaley ◽  
Qing Zhang ◽  
Kelly E. Caudle ◽  
P. David Rogers
Keyword(s):  
Multidrug Resistance ◽  
Minor Role ◽  
Azole Resistance ◽  
Content Type ◽  
Azole Antifungals ◽  
Zinc Cluster ◽  
Relative Contribution ◽  
Genes Encoding ◽  
High Level ◽  
A Minor

ABSTRACTThe utility of the azole antifungals for the treatment of invasive candidiasis is severely hampered by azole resistance inCandida glabrata. This resistance is mediated almost exclusively by activating mutations in the zinc cluster transcription factor Pdr1, which controls the genes encoding the multidrug resistance transporters Cdr1, Pdh1, and Snq2. However, the specific relative contributions of these transporters to resistance are not known. To address this question, theSAT1flipper method was used to deleteCDR1,PDH1, andSNQ2in a strain ofC. glabrataengineered to carry a clinically relevant activating mutation inPDR1. Susceptibility testing was performed according to the CLSI guidelines, with minor modifications, and confirmed with Etest strips. Of the single-transporter-deletion strains, only theCDR1deletion resulted in a decreased azole MIC. The deletion ofPDH1in combination withCDR1resulted in a moderate decrease in MIC compared to that observed with the deletion ofCDR1alone.SNQ2deletion only decreased the MIC in the triple-deletion strain in the absence of bothCDR1andPDH1. The deletion of all three transporters in combination decreased the MIC to the level observed in thePDR1deletion strains for some, but not all, azoles tested, which indicates that additional Pdr1 targets likely play a minor role in this process. These results indicate that while Cdr1 is the most important Pdr1-mediated multidrug resistance transporter for azole resistance in this clinical isolate, all three of these transporters contribute to its high-level resistance to the azole antifungals.

scholarly journals Genetic Analysis of the TOR Pathway in Aspergillus nidulans

2005 ◽  
Vol 4 (9) ◽  
pp. 1595-1598 ◽  
Author(s):  
Gregory J. Fitzgibbon ◽  
Igor Y. Morozov ◽  
Meriel G. Jones ◽  
Mark X. Caddick
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Genetic Analysis ◽  
Aspergillus Nidulans ◽  
Minor Role ◽  
Tor Signaling ◽  
Tor Pathway ◽  
Genes Encoding ◽  
Tor Kinase ◽  
Mutant Phenotypes ◽  
A Minor

ABSTRACT We identified five genes encoding components of the TOR signaling pathway within Aspergillus nidulans. Unlike the situation in Saccharomyces cerevisiae, there is only a single Tor kinase, as in plant and animal systems, and mutant phenotypes suggest that the TOR pathway plays only a minor role in regulating nitrogen metabolism.

Blocking eukaryotic initiation factor 4F complex formation does not inhibit the mTORC1-dependent activation of protein synthesis in cardiomyocytes

2009 ◽  
Vol 296 (2) ◽  
pp. H505-H514 ◽  
Author(s):  
Brandon P. H. Huang ◽  
Yanni Wang ◽  
Xuemin Wang ◽  
Zhuren Wang ◽  
Christopher G. Proud
Keyword(s):  
Protein Synthesis ◽  
Complex Formation ◽  
Mammalian Target Of Rapamycin ◽  
Initiation Factor ◽  
Minor Role ◽  
Eukaryotic Initiation Factor ◽  
Eukaryotic Initiation Factor 4E ◽  
Mtorc1 Signaling ◽  
A Minor ◽  
Rapid Activation

Activation of the mammalian target of rapamycin complex 1 (mTORC1) causes the dissociation of eukaryotic initiation factor 4E complex (eIF4E)-binding protein 1 (4E-BP1) from eIF4E, leading to increased eIF4F complex formation. mTORC1 positively regulates protein synthesis and is implicated in several diseases including cardiac hypertrophy, a potentially fatal disorder involving increased cardiomyocyte size. The importance of 4E-BP1 in mTORC1-regulated protein synthesis was investigated by overexpressing 4E-BP1, which blocks eIF4F formation in isolated primary cardiomyocytes without affecting other targets for mTORC1 signaling. Interestingly, blocking eIF4F formation did not impair the degree of activation of overall protein synthesis by the hypertrophic agent phenylephrine (PE), which, furthermore, remained dependent on mTORC1. Overexpressing 4E-BP1 also only had a small effect on PE-induced cardiomyocyte growth. Overexpressing 4E-BP1 did diminish the PE-stimulated synthesis of luciferase encoded by structured mRNAs, confirming that such mRNAs do require eIF4F for their translation in cardiomyocytes. These data imply that the substantial inhibition of cardiomyocyte protein synthesis and growth caused by inhibiting mTORC1 cannot be attributed to the activation of 4E-BP1 or loss of eIF4F complexes. Our data indicate that increased eIF4F formation plays, at most, only a minor role in the mTORC1-dependent activation of overall protein synthesis in these primary cells but is required for the translation of structured mRNAs. Therefore, other mTORC1 targets are more important in the inhibition by rapamycin of the rapid activation of protein synthesis and of cell growth.

Effects of endotoxin on iron uptake by the hepatocyte

1989 ◽  
Vol 257 (4) ◽  
pp. G524-G531 ◽  
Author(s):  
B. J. Potter ◽  
B. Blades ◽  
T. A. McHugh ◽  
R. M. Nunes ◽  
O. Beloqui ◽  
...  
Keyword(s):  
Protein Synthesis ◽  
Iron Uptake ◽  
Isolated Hepatocytes ◽  
Iron Storage ◽  
Sterile Saline ◽  
Significant Difference ◽  
Previously Treated ◽  
And Control ◽  
In Cells

Administration of endotoxins is often followed within 12-24 h by marked hypoferremia. Because the hepatocyte is the major site of both iron storage and transferrin synthesis, we have investigated the effects of an Escherichia coli endotoxin (lipopolysaccharide, LPS) on these parameters on isolated hepatocytes from normal Wistar rats (ND), rats previously treated intraperitoneally with 2.5 mg/kg (LD) or 25 mg/kg (HD) LPS, and control rats injected intraperitoneally with sterile saline (CD). No effects were observed on iron uptake from transferrin by ND cells incubated in vitro with up to 350 micrograms LPS/10(7) hepatocytes. There was also no significant difference in iron uptake between CD, HD, and LD hepatocytes 1 h after LPS injection. However, hepatocytes isolated 24 h after LPS administration took up iron significantly faster than controls. The uptake of non-transferrin-bound iron was also increased in HD and LD hepatocytes at 24 h but only in HD cells at 1 h. Transferrin binding was not altered in LPS-treated cells from ND rats but was depressed in cells from LPS-treated rats both at 1 h and at 24 h after injection. Transferrin receptor recycling was significantly increased at 24 h in cells from both LD and HD rats. Transferrin and total protein synthesis were also depressed at 1 h in LPS-treated rats, returning to normal values at 24 h. Direct preincubation of ND cells, however, failed to increase synthesis except at the highest concentrations of LPS. We conclude that LPS has an immediate (although indirect) effect on protein synthesis by the hepatocyte but not on iron uptake.(ABSTRACT TRUNCATED AT 250 WORDS)

scholarly journals Decoding Viral Infection by Ribosome Profiling

2015 ◽  
Vol 89 (12) ◽  
pp. 6164-6166 ◽  
Author(s):  
Noam Stern-Ginossar
Keyword(s):  
Protein Synthesis ◽  
Viral Infection ◽  
Human Cytomegalovirus ◽  
Deep Sequencing ◽  
Kaposi's Sarcoma ◽  
Ribosome Profiling ◽  
Translation Regulation ◽  
Live Cells ◽  
Coding Capacity ◽  
In Cells

Ribosome profiling is an emerging technique that uses deep sequencing to monitor translation in live cells. Studies using ribosome profiling have already provided novel insights into the identities and amounts of the proteins being produced in cells, as well as novel insights into the mechanism of protein synthesis and translation regulation. Application of ribosome profiling to cells infected with human cytomegalovirus and Kaposi's sarcoma-associated herpesvirus revealed unanticipated complexity in the coding capacity of herpesviruses. Here, I discuss these results and how the application of ribosome profiling to cells infected with other viruses can reveal novel insights into the process of infection.

scholarly journals Specific Osmolyte Transporters Mediate Bile Tolerance in Listeria monocytogenes

2009 ◽  
Vol 77 (11) ◽  
pp. 4895-4904 ◽  
Author(s):  
Debbie Watson ◽  
Roy D. Sleator ◽  
Pat G. Casey ◽  
Colin Hill ◽  
Cormac G. M. Gahan
Keyword(s):  
Listeria Monocytogenes ◽  
Oral Infection ◽  
Infection Model ◽  
Minor Role ◽  
Uptake System ◽  
Systematic Analysis ◽  
Bile Tolerance ◽  
Genes Encoding ◽  
A Minor

ABSTRACT The food-borne pathogenic bacterium Listeria monocytogenes has the potential to adapt to an array of suboptimal growth environments encountered within the host. The pathogen is relatively bile tolerant and has the capacity to survive and grow within both the small intestine and the gallbladder in murine models of oral infection. We have previously demonstrated a role for the principal carnitine transport system of L. monocytogenes (OpuC) in gastrointestinal survival of the pathogen (R. Sleator, J. Wouters, C. G. M. Gahan, T. Abee, and C. Hill, Appl. Environ. Microbiol. 67:2692-2698, 2001). However, the mechanisms by which OpuC, or indeed carnitine, protects the pathogen in this environment are unclear. In the current study, systematic analysis of strains with mutations in osmolyte transporters revealed a role for OpuC in resisting the acute toxicity of bile, with a minor role also played by BetL, a secondary betaine uptake system which also exhibits a low affinity for carnitine. In addition, the toxic effects of bile on wild-type L. monocytogenes cells were ameliorated when carnitine (but not betaine) was added to the medium. lux-promoter fusions to the promoters of the genes encoding the principal osmolyte uptake systems Gbu, BetL, and OpuC and the known bile tolerance system BilE were constructed. Promoter activity for all systems was significantly induced in the presence of bile, with the opuC and bilE promoters exhibiting the highest levels of bile-dependent expression in vitro and the betL and bilE promoters showing the highest expression levels in the intestines of orally inoculated mice. A direct comparison of all osmolyte transporter mutants in a murine oral infection model confirmed a major role for OpuC in intestinal persistence and systemic invasion and a minor role for the BetL transporter in fecal carriage. This study therefore demonstrates a previously unrecognized function for osmolyte uptake systems in bile tolerance in L. monocytogenes.

scholarly journals Zinc transporter-2 (ZnT2) variants are localized to distinct subcellular compartments and functionally transport zinc

2009 ◽  
Vol 422 (1) ◽  
pp. 43-52 ◽  
Author(s):  
Veronica Lopez ◽  
Shannon L. Kelleher
Keyword(s):  
Secretory Vesicle ◽  
Zinc Transporter ◽  
Minor Role ◽  
Zinc Transport ◽  
Cellular Functions ◽  
Gene Encoding ◽  
Endogenous Expression ◽  
A Minor ◽  
And Function ◽  
In Cells

ZnT2 (zinc transporter-2) expression is restricted to tissues with unique zinc requirements such as mammary and prostate glands. We previously determined that ZnT2 plays a major role in zinc export from mammary glands, as women with a mutation in the gene encoding ZnT2 (SLC30A2) had an ∼75% reduction in milk zinc concentration. Two distinct human ZnT2 isoforms (∼42 and 35 kDa) are predicted to result from alternative splicing of SLC30A2. We examined the localization and function of each ZnT2 isoform, in cells generated to express ZnT2–HA (haemagglutinin) fusion proteins. The 42 kDa isoform was localized primarily to the endosomal/secretory compartment and overexpression resulted in increased zinc vesicularization. In contrast, the 35 kDa isoform is associated with the plasma membrane. Importantly, zinc transport was higher in cells over-expressing each isoform, indicating that both proteins are functional. Endogenous expression of the secretory vesicle-associated ZnT2 isoform predominates in mammary cells and expression is higher in secreting cells, whereas the smaller isoform plays a minor role in zinc export, directly reflecting the secretory function of the mammary gland. Together our data shed further light on the complex integration of cellular zinc transport mechanisms, which may be facilitated by multiple isoforms of specific zinc transporters with unique cellular functions.

scholarly journals Lysine metabolism across the hindquarters of sheep; effect of intake on transfers from plasma and red blood cells

2001 ◽  
Vol 85 (5) ◽  
pp. 565-573 ◽  
Author(s):  
Isabelle C. Savary ◽  
Simone O. Hoskin ◽  
Ngaire Dennison ◽  
Gerald E. Lobley
Keyword(s):  
Protein Synthesis ◽  
Red Blood Cells ◽  
Blood Cells ◽  
Vena Cava ◽  
Whole Body ◽  
Minor Role ◽  
Four Levels ◽  
Arterial Plasma ◽  
A Minor ◽  
Linear Manner

Both plasma and red blood cells contain amino acids (AA), but the relative amount of AA transferred from each vascular compartment to the tissues remains unclear. For splanchnic tissues, the relative transfers between the plasma, the red blood cells and the tissues may vary with nutritional state, but whether the same situation pertains for other tissues is not known. The current study focused on the transfer of lysine from plasma and red blood cells across the hindquarters of sheep offered four levels of intakes (0.5, 1.0, 1.5 and 2.5×maintenance energy). This design, coupled with use of [U-13C]lysine as tracer, also allowed the effect of intake on protein kinetics to be examined. At all intakes, the concentration of lysine in the sheep’ red blood cells exceeded that in plasma by 50 % (P<0.001), while the distribution of labelled lysine between the plasma and the red blood cells was 0.71:0.29. Net lysine uptake by the hindquarters increased in a linear manner (P<0.001) with intake, with more than 90 % extracted from the plasma. Free lysine enrichments in plasma from the posterior vena cava were less than that from the artery (P<0.001), but those in red blood cells were not different between the artery and vein. The red blood cells thus play a minor role in the transfers to and from the hindquarter tissues, regardless of intake. Based on plasma transfers and the enrichment of lysine in arterial plasma, hindquarter protein synthesis increased linearly with intake (P<0.001). In contrast, protein breakdown was unaffected by intake. The contribution of hindquarter protein synthesis to whole-body lysine flux remained unchanged with intake (18–20 %).

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