scholarly journals De NovoEmergence of Peptides That Confer Antibiotic Resistance

mBio ◽  
2019 ◽  
Vol 10 (3) ◽  
Author(s):  
Michael Knopp ◽  
Jonina S. Gudmundsdottir ◽  
Tobias Nilsson ◽  
Finja König ◽  
Omar Warsi ◽  
...  
Keyword(s):  
Membrane Potential ◽  
Comparative Genomics ◽  
Dna Sequences ◽  
De Novo ◽  
Drug Uptake ◽  
Aminoglycoside Resistance ◽  
Noncoding Dna ◽  
Ancestral Gene ◽  
New Genes

ABSTRACTThe origin of novel genes and beneficial functions is of fundamental interest in evolutionary biology. New genes can originate from different mechanisms, including horizontal gene transfer, duplication-divergence, andde novofrom noncoding DNA sequences. Comparative genomics has generated strong evidence forde novoemergence of genes in various organisms, but experimental demonstration of this process has been limited to localized randomization in preexisting structural scaffolds. This bypasses the basic requirement ofde novogene emergence, i.e., lack of an ancestral gene. We constructed highly diverse plasmid libraries encoding randomly generated open reading frames and expressed them inEscherichia colito identify short peptides that could confer a beneficial and selectable phenotypein vivo(in a living cell). Selections on antibiotic-containing agar plates resulted in the identification of three peptides that increased aminoglycoside resistance up to 48-fold. Combining genetic and functional analyses, we show that the peptides are highly hydrophobic, and by inserting into the membrane, they reduce membrane potential, decrease aminoglycoside uptake, and thereby confer high-level resistance. This study demonstrates that randomized DNA sequences can encode peptides that confer selective benefits and illustrates how expression of random sequences could spark the origination of new genes. In addition, our results also show that this question can be addressed experimentally by expression of highly diverse sequence libraries and subsequent selection for specific functions, such as resistance to toxic compounds, the ability to rescue auxotrophic/temperature-sensitive mutants, and growth on normally nonused carbon sources, allowing the exploration of many different phenotypes.IMPORTANCEDe novogene origination from nonfunctional DNA sequences was long assumed to be implausible. However, recent studies have shown that large fractions of genomic noncoding DNA are transcribed and translated, potentially generating new genes. Experimental validation of this process so far has been limited to comparative genomics,in vitroselections, or partial randomizations. Here, we describe selection of novel peptidesin vivousing fully random synthetic expression libraries. The peptides confer aminoglycoside resistance by inserting into the bacterial membrane and thereby partly reducing membrane potential and decreasing drug uptake. Our results show that beneficial peptides can be selected from random sequence poolsin vivoand support the idea that expression of noncoding sequences could spark the origination of new genes.

scholarly journals Synthesis of Signals for De Novo DNA Methylation in Neurospora crassa

2003 ◽  
Vol 23 (7) ◽  
pp. 2379-2394 ◽  
Author(s):  
Hisashi Tamaru ◽  
Eric U. Selker
Keyword(s):  
Dna Methylation ◽  
Neurospora Crassa ◽  
Point Mutation ◽  
Dna Sequences ◽  
De Novo ◽  
Test Site ◽  
Minor Groove ◽  
Binding Motif ◽  
Repeat Induced Point Mutation

ABSTRACT Most 5-methylcytosine in Neurospora crassa occurs in A:T-rich sequences high in TpA dinucleotides, hallmarks of repeat-induced point mutation. To investigate how such sequences induce methylation, we developed a sensitive in vivo system. Tests of various 25- to 100-bp synthetic DNA sequences revealed that both T and A residues were required on a given strand to induce appreciable methylation. Segments composed of (TAAA) n or (TTAA) n were the most potent signals; 25-mers induced robust methylation at the special test site, and a 75-mer induced methylation elsewhere. G:C base pairs inhibited methylation, and cytosines 5′ of ApT dinucleotides were particularly inhibitory. Weak signals could be strengthened by extending their lengths. A:T tracts as short as two were found to cooperate to induce methylation. Distamycin, which, like the AT-hook DNA binding motif found in proteins such as mammalian HMG-I, binds to the minor groove of A:T-rich sequences, suppressed DNA methylation and gene silencing. We also found a correlation between the strength of methylation signals and their binding to an AT-hook protein (HMG-I) and to activities in a Neurospora extract. We propose that de novo DNA methylation in Neurospora cells is triggered by cooperative recognition of the minor groove of multiple short A:T tracts. Similarities between sequences subjected to repeat-induced point mutation in Neurospora crassa and A:T-rich repeated sequences in heterochromatin in other organisms suggest that related mechanisms control silent chromatin in fungi, plants, and animals.

scholarly journals Glucocorticoids Regulate Plasma Membrane Potential During Rat Thymocyte Apoptosis in Vivo and in Vitro

Endocrinology ◽  
2001 ◽  
Vol 142 (1) ◽  
pp. 421-429 ◽  
Author(s):  
Cynthia L. Mann ◽  
John A. Cidlowski
Keyword(s):  
Plasma Membrane ◽  
Membrane Potential ◽  
Glucocorticoid Receptors ◽  
De Novo ◽  
Strong Association ◽  
Glucocorticoid Treatment ◽  
Plasma Membrane Potential ◽  
Induced Apoptosis

Abstract Glucocorticoids induce a series of profound biochemical changes in thymocytes that initiate apoptosis; however, the pathways beyond receptor transactivation that lead to this form of cell death are not fully understood. In this study, we report a novel site of action for glucocorticoids at the site of the plasma membrane. Specifically, we find that glucocorticoids induce the loss of plasma membrane potential both in vivo and in vitro. The glucocorticoid-induced loss of plasma membrane potential in cultured primary isolated rat thymocytes was both dose and time dependent. Other steroid hormones, including progesterone, estrogen, and testosterone, fail to alter the depolarization state of the thymocyte plasma membrane. Interestingly, other nonsteroid stimuli that also activate apoptosis in thymocytes also lead to cellular depolarization. In contrast, HeLa cells, which contain functional glucocorticoid receptors but do not die in response to hormone, do not alter their plasma membrane potential in response to glucocorticoids, indicating a strong association between depolarization and apoptosis. Furthermore, the ability of glucocorticoids to depolarize the plasma membrane of thymocytes required the interaction of glucocorticoids with their cognate receptor, because RU486 failed to depolarize thymocytes and antagonized the effect of glucocorticoids. Finally, experiments using inhibitors of transcription and translation indicated that the loss of plasma membrane potential in thymocytes following glucocorticoid treatment required de novo gene expression. The results of these studies establish that the loss of plasma membrane potential is an early important feature of glucocorticoid-induced apoptosis of thymocytes.

scholarly journals Model system identification of novel congenital heart disease gene candidates: focus on RPL13

2019 ◽  
Vol 28 (23) ◽  
pp. 3954-3969 ◽  
Author(s):  
Analyne M Schroeder ◽  
Massoud Allahyari ◽  
Georg Vogler ◽  
Maria A Missinato ◽  
Tanja Nielsen ◽  
...  
Keyword(s):  
Congenital Heart Disease ◽  
Heart Disease ◽  
High Throughput ◽  
Heart Development ◽  
Congenital Heart ◽  
De Novo ◽  
Model Systems ◽  
New Genes ◽  
Cardiac Model

Abstract Genetics is a significant factor contributing to congenital heart disease (CHD), but our understanding of the genetic players and networks involved in CHD pathogenesis is limited. Here, we searched for de novo copy number variations (CNVs) in a cohort of 167 CHD patients to identify DNA segments containing potential pathogenic genes. Our search focused on new candidate disease genes within 19 deleted de novo CNVs, which did not cover known CHD genes. For this study, we developed an integrated high-throughput phenotypical platform to probe for defects in cardiogenesis and cardiac output in human induced pluripotent stem cell (iPSC)-derived multipotent cardiac progenitor (MCPs) cells and, in parallel, in the Drosophila in vivo heart model. Notably, knockdown (KD) in MCPs of RPL13, a ribosomal gene and SON, an RNA splicing cofactor, reduced proliferation and differentiation of cardiomyocytes, while increasing fibroblasts. In the fly, heart-specific RpL13 KD, predominantly at embryonic stages, resulted in a striking ‘no heart’ phenotype. KD of Son and Pdss2, among others, caused structural and functional defects, including reduced or abolished contractility, respectively. In summary, using a combination of human genetics and cardiac model systems, we identified new genes as candidates for causing human CHD, with particular emphasis on ribosomal genes, such as RPL13. This powerful, novel approach of combining cardiac phenotyping in human MCPs and in the in vivo Drosophila heart at high throughput will allow for testing large numbers of CHD candidates, based on patient genomic data, and for building upon existing genetic networks involved in heart development and disease.

scholarly journals DanQ: a hybrid convolutional and recurrent deep neural network for quantifying the function of DNA sequences

2015 ◽  
Author(s):  
Daniel Quang ◽  
Xiaohui Xie
Keyword(s):  
Neural Network ◽  
Dna Sequences ◽  
Short Term Memory ◽  
De Novo ◽  
Short Term ◽  
Noncoding Dna ◽  
Regulatory Motifs ◽  
Precision Recall Curve ◽  
Long Short Term Memory

Modeling the properties and functions of DNA sequences is an important, but challenging task in the broad field of genomics. This task is particularly difficult for noncoding DNA, the vast majority of which is still poorly understood in terms of function. A powerful predictive model for the function of noncoding DNA can have enormous benefit for both basic science and translational research because over 98% of the human genome is noncoding and 93% of disease-associated variants lie in these regions. To address this need, we propose DanQ, a novel hybrid convolutional and bi-directional long short-term memory recurrent neural network framework for predicting noncoding function de novo from sequence. In the DanQ model, the convolution layer captures regulatory motifs, while the recurrent layer captures long-term dependencies between the motifs in order to learn a regulatory "grammar" to improve predictions. DanQ improves considerably upon other models across several metrics. For some regulatory markers, DanQ can achieve over a 50% relative improvement in the area under the precision-recall curve metric compared to related models.

Search for mutations of the interferon-induced transmembrane protein 5 (IFITM5) gene in patients with osteogenesis imperfecta

2019 ◽  
pp. 21-29
Author(s):  
А.Р. Зарипова ◽  
Л.Р. Нургалиева ◽  
А.В. Тюрин ◽  
И.Р. Минниахметов ◽  
Р.И. Хусаинова
Keyword(s):  
Osteogenesis Imperfecta ◽  
De Novo ◽  
Transmembrane Protein ◽  
Clinical Signs ◽  
Clinical Manifestations ◽  
Heterozygous Mutation ◽  
Type I ◽  
New Genes ◽  
Wide Range ◽  
Type V

Проведено исследование гена интерферон индуцированного трансмембранного белка 5 (IFITM5) у 99 пациентов с несовершенным остеогенезом (НО) из 86 неродственных семей. НО - клинически и генетически гетерогенное наследственное заболевание соединительной ткани, основное клиническое проявление которого - множественные переломы, начиная с неонатального периода жизни, зачастую приводящие к инвалидизации с детского возраста. К основным клиническим признакам НО относятся голубые склеры, потеря слуха, аномалия дентина, повышенная ломкость костей, нарушения роста и осанки с развитием характерных инвалидизирующих деформаций костей и сопутствующих проблем, включающих дыхательные, неврологические, сердечные, почечные нарушения. НО встречается как у мужчин, так и у женщин. До сих пор не определена степень генетической гетерогенности заболевания. На сегодняшний день известно 20 генов, вовлеченных в патогенез НО, и исследователи разных стран продолжают искать новые гены. В последнее десятилетие стало известно, что аутосомно-рецессивные, аутосомно-доминантные и Х-сцепленные мутации в широком спектре генов, кодирующих белки, которые участвуют в синтезе коллагена I типа, его процессинге, секреции и посттрансляционной модификации, а также в белках, которые регулируют дифференцировку и активность костеобразующих клеток, вызывают НО. Мутации в гене IFITM5, также называемом BRIL (bone-restricted IFITM-like protein), участвующем в формировании остеобластов, приводят к развитию НО типа V. До 5% пациентов имеют НО типа V, который характеризуется образованием гиперпластического каллуса после переломов, кальцификацией межкостной мембраны предплечья и сетчатым рисунком ламелирования, наблюдаемого при гистологическом исследовании кости. В 2012 г. гетерозиготная мутация (c.-14C> T) в 5’-нетранслируемой области (UTR) гена IFITM5 была идентифицирована как основная причина НО V типа. В представленной работе проведен анализ гена IFITM5 и идентифицирована мутация c.-14C>T, возникшая de novo, у одного пациента с НО, которому впоследствии был установлен V тип заболевания. Также выявлены три известных полиморфных варианта: rs57285449; c.80G>C (p.Gly27Ala) и rs2293745; c.187-45C>T и rs755971385 c.279G>A (p.Thr93=) и один ранее не описанный вариант: c.128G>A (p.Ser43Asn) AGC>AAC (S/D), которые не являются патогенными. В статье уделяется внимание особенностям клинических проявлений НО V типа и рекомендуется определение мутации c.-14C>T в гене IFITM5 при подозрении на данную форму заболевания. A study was made of interferon-induced transmembrane protein 5 gene (IFITM5) in 99 patients with osteogenesis imperfecta (OI) from 86 unrelated families and a search for pathogenic gene variants involved in the formation of the disease phenotype. OI is a clinically and genetically heterogeneous hereditary disease of the connective tissue, the main clinical manifestation of which is multiple fractures, starting from the natal period of life, often leading to disability from childhood. The main clinical signs of OI include blue sclera, hearing loss, anomaly of dentin, increased fragility of bones, impaired growth and posture, with the development of characteristic disabling bone deformities and associated problems, including respiratory, neurological, cardiac, and renal disorders. OI occurs in both men and women. The degree of genetic heterogeneity of the disease has not yet been determined. To date, 20 genes are known to be involved in the pathogenesis of OI, and researchers from different countries continue to search for new genes. In the last decade, it has become known that autosomal recessive, autosomal dominant and X-linked mutations in a wide range of genes encoding proteins that are involved in the synthesis of type I collagen, its processing, secretion and post-translational modification, as well as in proteins that regulate the differentiation and activity of bone-forming cells cause OI. Mutations in the IFITM5 gene, also called BRIL (bone-restricted IFITM-like protein), involved in the formation of osteoblasts, lead to the development of OI type V. Up to 5% of patients have OI type V, which is characterized by the formation of a hyperplastic callus after fractures, calcification of the interosseous membrane of the forearm, and a mesh lamellar pattern observed during histological examination of the bone. In 2012, a heterozygous mutation (c.-14C> T) in the 5’-untranslated region (UTR) of the IFITM5 gene was identified as the main cause of OI type V. In the present work, the IFITM5 gene was analyzed and the de novo c.-14C> T mutation was identified in one patient with OI who was subsequently diagnosed with type V of the disease. Three known polymorphic variants were also identified: rs57285449; c.80G> C (p.Gly27Ala) and rs2293745; c.187-45C> T and rs755971385 c.279G> A (p.Thr93 =) and one previously undescribed variant: c.128G> A (p.Ser43Asn) AGC> AAC (S / D), which were not pathogenic. The article focuses on the features of the clinical manifestations of OI type V, and it is recommended to determine the c.-14C> T mutation in the IFITM5 gene if this form of the disease is suspected.

scholarly journals DNA thermodynamics shape chromosome organization and topology

2013 ◽  
Vol 41 (2) ◽  
pp. 548-553 ◽  
Author(s):  
Andrew A. Travers ◽  
Georgi Muskhelishvili
Keyword(s):  
Dna Sequence ◽  
Dna Sequences ◽  
Chromosome Organization ◽  
Topological Properties ◽  
Genetic Organization ◽  
And Topology ◽  
Dna Translocases

How much information is encoded in the DNA sequence of an organism? We argue that the informational, mechanical and topological properties of DNA are interdependent and act together to specify the primary characteristics of genetic organization and chromatin structures. Superhelicity generated in vivo, in part by the action of DNA translocases, can be transmitted to topologically sensitive regions encoded by less stable DNA sequences.

scholarly journals Review of T-2307, an Investigational Agent That Causes Collapse of Fungal Mitochondrial Membrane Potential

2021 ◽  
Vol 7 (2) ◽  
pp. 130
Author(s):  
Nathan P. Wiederhold
Keyword(s):  
Membrane Potential ◽  
Mitochondrial Membrane Potential ◽  
Candida Species ◽  
Mammalian Cells ◽  
Mitochondrial Membrane ◽  
Fungal Infections ◽  
Published Data ◽  
Candida Auris

Invasive infections caused by Candida that are resistant to clinically available antifungals are of increasing concern. Increasing rates of fluconazole resistance in non-albicans Candida species have been documented in multiple countries on several continents. This situation has been further exacerbated over the last several years by Candida auris, as isolates of this emerging pathogen that are often resistant to multiple antifungals. T-2307 is an aromatic diamidine currently in development for the treatment of invasive fungal infections. This agent has been shown to selectively cause the collapse of the mitochondrial membrane potential in yeasts when compared to mammalian cells. In vitro activity has been demonstrated against Candida species, including C. albicans, C. glabrata, and C. auris strains, which are resistant to azole and echinocandin antifungals. Activity has also been reported against Cryptococcus species, and this has translated into in vivo efficacy in experimental models of invasive candidiasis and cryptococcosis. However, little is known regarding the clinical efficacy and safety of this agent, as published data from studies involving humans are not currently available.

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