scholarly journals Oxidative Pathways of Deoxyribose and Deoxyribonate Catabolism

mSystems ◽  
2019 ◽  
Vol 4 (1) ◽  
Author(s):  
Morgan N. Price ◽  
Jayashree Ray ◽  
Anthony T. Iavarone ◽  
Hans K. Carlson ◽  
Elizabeth M. Ryan ◽  
...  

ABSTRACTUsing genome-wide mutant fitness assays in diverse bacteria, we identified novel oxidative pathways for the catabolism of 2-deoxy-d-ribose and 2-deoxy-d-ribonate. We propose that deoxyribose is oxidized to deoxyribonate, oxidized to ketodeoxyribonate, and cleaved to acetyl coenzyme A (acetyl-CoA) and glyceryl-CoA. We have genetic evidence for this pathway in three genera of bacteria, and we confirmed the oxidation of deoxyribose to ketodeoxyribonatein vitro. InPseudomonas simiae, the expression of enzymes in the pathway is induced by deoxyribose or deoxyribonate, while inParaburkholderia bryophilaand inBurkholderia phytofirmans, the pathway proceeds in parallel with the known deoxyribose 5-phosphate aldolase pathway. We identified another oxidative pathway for the catabolism of deoxyribonate, with acyl-CoA intermediates, inKlebsiella michiganensis. Of these four bacteria, onlyP. simiaerelies entirely on an oxidative pathway to consume deoxyribose. The deoxyribose dehydrogenase ofP. simiaeis either nonspecific or evolved recently, as this enzyme is very similar to a novel vanillin dehydrogenase fromPseudomonas putidathat we identified. So, we propose that these oxidative pathways evolved primarily to consume deoxyribonate, which is a waste product of metabolism.IMPORTANCEDeoxyribose is one of the building blocks of DNA and is released when cells die and their DNA degrades. We identified a bacterium that can grow with deoxyribose as its sole source of carbon even though its genome does not contain any of the known genes for breaking down deoxyribose. By growing many mutants of this bacterium together on deoxyribose and using DNA sequencing to measure the change in the mutants’ abundance, we identified multiple protein-coding genes that are required for growth on deoxyribose. Based on the similarity of these proteins to enzymes of known function, we propose a 6-step pathway in which deoxyribose is oxidized and then cleaved. Diverse bacteria use a portion of this pathway to break down a related compound, deoxyribonate, which is a waste product of metabolism. Our study illustrates the utility of large-scale bacterial genetics to identify previously unknown metabolic pathways.

2017 ◽  
Author(s):  
Morgan N. Price ◽  
Jayashree Ray ◽  
Anthony T. Iavarone ◽  
Hans K. Carlson ◽  
Elizabeth M. Ryan ◽  
...  

AbstractUsing genome-wide mutant fitness assays in diverse bacteria, we identified novel oxidative pathways for the catabolism of 2-deoxy-D-ribose and 2-deoxy-D-ribonate. We propose that deoxyribose is oxidized to deoxyribonate, oxidized to ketodeoxyribonate, and cleaved to acetyl-CoA and glyceryl-CoA. We have genetic evidence for this pathway in three genera of bacteria, and we confirmed the oxidation of deoxyribose to ketodeoxyribonatein vitro. InPseudomonas simiae, the expression of enzymes in the pathway is induced by deoxyribose or deoxyribonate, while inParaburkholderia bryophilaand inBurkholderia phytofirmans, the pathway proceeds in parallel with the known deoxyribose 5-phosphate aldolase pathway. We identified another oxidative pathway for the catabolism of deoxyribonate, with acyl-CoA intermediates, inKlebsiella michiganensis. Of these four bacteria, onlyP. simiaerelies entirely on an oxidative pathway to consume deoxyribose. The deoxyribose dehydrogenase ofP. simiaeis either non-specific or evolved recently, as this enzyme is very similar to a novel vanillin dehydrogenase fromPseudomonas putidathat we identified. So, we propose that these oxidative pathways evolved primarily to consume deoxyribonate, which is a waste product of metabolism.ImportanceDeoxyribose is one of the building blocks of DNA and is released when cells die and their DNA degrades. We identified a bacterium that can grow with deoxyribose as its sole source of carbon even though its genome does not encode any of the known genes for breaking down deoxyribose. By growing many mutants of this bacterium together on deoxyribose and using DNA sequencing to measure the change in the mutants’ abundance, we identified multiple protein-coding genes that are required for growth on deoxyribose. Based on the similarity of these proteins to enzymes of known function, we propose a 6-step pathway in which deoxyribose is oxidized and then cleaved. Diverse bacteria use a portion of this pathway to break down a related compound, deoxyribonate, which is a waste product of human metabolism and is present in urine. Our study illustrates the utility of large-scale bacterial genetics to identify previously unknown metabolic pathways.


2020 ◽  
Author(s):  
Shiyang Liu ◽  
Nathan Harmston ◽  
Trudy Lee Glaser ◽  
Yunka Wong ◽  
Zheng Zhong ◽  
...  

AbstractBackgroundWnt signaling is an evolutionarily conserved developmental pathway that is frequently hyperactivated in cancer. While multiple protein-coding genes regulated by Wnt signaling are known, the functional lncRNAs regulated by Wnt signaling have not been systematically characterized.ResultsWe comprehensively mapped lncRNAs from an orthotopic Wnt-addicted pancreatic cancer model, identifying 3,633 lncRNAs, of which 1,503 were regulated by Wnt signaling. We found lncRNAs were much more sensitive to changes in Wnt signaling in xenografts than in cultured cells. To functionally validate Wnt-regulated lncRNAs, we performed CRISPRi screens to assess their role in cancer cell proliferation. Consistent with previous genome-wide lncRNA CRISPRi screens, around 1% (13/1,503) of the Wnt-regulated lncRNAs could modify cancer cell growth in vitro. This included CCAT1 and LINC00263, previously reported to regulate cancer growth. Using an in vivo CRISPRi screen, we doubled the discovery rate, identifying twice as many Wnt-regulated lncRNAs (25/1,503) that had a functional effect on cancer cell growth.ConclusionsOur study demonstrates the value of studying lncRNA functions in vivo, provides a valuable resource of lncRNAs regulated by Wnt signaling and establishes a framework for systematic discovery of functional lncRNAs.


2019 ◽  
Vol 201 (17) ◽  
Author(s):  
Dragutin J. Savic ◽  
Scott V. Nguyen ◽  
Kimberly McCullor ◽  
W. Michael McShan

ABSTRACTA large-scale genomic inversion encompassing 0.79 Mb of the 1.816-Mb-longStreptococcus pyogenesserotype M49 strain NZ131 chromosome spontaneously occurs in a minor subpopulation of cells, and in this report genetic selection was used to obtain a stable lineage with this chromosomal rearrangement. This inversion, which drastically displaces theorisite relative to the terminus, changes the relative length of the replication arms so that one replichore is approximately 0.41 Mb while the other is about 1.40 Mb in length. Genomic reversion to the original chromosome constellation is not observed in PCR-monitored analyses after 180 generations of growth in rich medium. Compared to the parental strain, the inversion surprisingly demonstrates a nearly identical growth pattern in the first phase of the exponential phase, but differences do occur when resources in the medium become limited. When cultured separately in rich medium during prolonged stationary phase or in an experimental acute infection animal model (Galleria mellonella), the parental strain and the invertant have equivalent survival rates. However, when they are coincubated together, bothin vitroandin vivo, the survival of the invertant declines relative to the level for the parental strain. The accompanying aspect of the study suggests that inversions taking place nearoriCalways happen to secure the linkage oforiCto DNA sequences responsible for chromosome partition. The biological relevance of large-scale inversions is also discussed.IMPORTANCEBased on our previous work, we created to our knowledge the largest asymmetric inversion, covering 43.5% of theS. pyogenesgenome. In spite of a drastic replacement of origin of replication and the unbalanced size of replichores (1.4 Mb versus 0.41 Mb), the invertant, when not challenged with its progenitor, showed impressive vitality for growthin vitroand in pathogenesis assays. The mutant supports the existing idea that slightly deleterious mutations can provide the setting for secondary adaptive changes. Furthermore, comparative analysis of the mutant with previously published data strongly indicates that even large genomic rearrangements survive provided that the integrity of theoriCand the chromosome partition cluster is preserved.


2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Steve Noone ◽  
Alison Branch ◽  
Melissa Sherring

Purpose Positive behavioural support (PBS) as a framework for delivering quality services is recognised in important policy documents (CQC, 2020; NICE, 2018), yet there is an absence in the literature on how this could be implemented on a large scale. The purpose of this paper is to describe a recent implementation of a workforce strategy to develop PBS across social care and health staff and family carers, within the footprint of a large integrated care system. Design/methodology/approach A logic model describes how an initial scoping exercise led to the production of a regional workforce strategy based on the PBS Competence Framework (2015). It shows how the creation of a regional steering group was able to coordinate important developmental stages and integrate multiple agencies into a single strategy to implement teaching and education in PBS. It describes the number of people who received teaching and education in PBS and the regional impact of the project in promoting cultural change within services. Findings This paper demonstrates a proof of concept that it is possible to translate the PBS Competency Framework (2015) into accredited courses. Initial scoping work highlighted the ineffectiveness of traditional training in PBS. Using blended learning and competency-based supervision and assessment, it was possible to create a new way to promote large-scale service developments in PBS supported by the governance of a new organisational structure. This also included family training delivered by family trainers. This builds on the ideas by Denne et al. (2020) that many of the necessary building blocks of implementation already exist within a system. Social implications A co-ordinated teaching and education strategy in PBS may help a wide range of carers to become more effective in supporting the people they care for. Originality/value This is the first attempt to describe the implementation of a framework for PBS within a defined geographical location. It describes the collaboration of health and social care planners and a local university to create a suite of courses built around the PBS coalition competency framework.


2016 ◽  
Vol 61 (2) ◽  
Author(s):  
Jees Sebastian ◽  
Sharmada Swaminath ◽  
Rashmi Ravindran Nair ◽  
Kishor Jakkala ◽  
Atul Pradhan ◽  
...  

ABSTRACT Bacterial persisters are a subpopulation of cells that can tolerate lethal concentrations of antibiotics. However, the possibility of the emergence of genetically resistant mutants from antibiotic persister cell populations, upon continued exposure to lethal concentrations of antibiotics, remained unexplored. In the present study, we found that Mycobacterium tuberculosis cells exposed continuously to lethal concentrations of rifampin (RIF) or moxifloxacin (MXF) for prolonged durations showed killing, RIF/MXF persistence, and regrowth phases. RIF-resistant or MXF-resistant mutants carrying clinically relevant mutations in the rpoB or gyrA gene, respectively, were found to emerge at high frequency from the RIF persistence phase population. A Luria-Delbruck fluctuation experiment using RIF-exposed M. tuberculosis cells showed that the rpoB mutants were not preexistent in the population but were formed de novo from the RIF persistence phase population. The RIF persistence phase M. tuberculosis cells carried elevated levels of hydroxyl radical that inflicted extensive genome-wide mutations, generating RIF-resistant mutants. Consistent with the elevated levels of hydroxyl radical-mediated genome-wide random mutagenesis, MXF-resistant M. tuberculosis gyrA de novo mutants could be selected from the RIF persistence phase cells. Thus, unlike previous studies, which showed emergence of genetically resistant mutants upon exposure of bacteria for short durations to sublethal concentrations of antibiotics, our study demonstrates that continuous prolonged exposure of M. tuberculosis cells to lethal concentrations of an antibiotic generates antibiotic persistence phase cells that form a reservoir for the generation of genetically resistant mutants to the same antibiotic or another antibiotic. These findings may have clinical significance in the emergence of drug-resistant tubercle bacilli.


2013 ◽  
Vol 79 (19) ◽  
pp. 6050-6058 ◽  
Author(s):  
Christoph Knuf ◽  
Intawat Nookaew ◽  
Stephen H. Brown ◽  
Michael McCulloch ◽  
Alan Berry ◽  
...  

ABSTRACTMalic acid has great potential for replacing petrochemical building blocks in the future. For this application, high yields, rates, and titers are essential in order to sustain a viable biotechnological production process. Natural high-capacity malic acid producers like the malic acid producerAspergillus flavushave so far been disqualified because of special growth requirements or the production of mycotoxins. AsA. oryzaeis a very close relative or even an ecotype ofA. flavus, it is likely that its high malic acid production capabilities with a generally regarded as safe (GRAS) status may be combined with already existing large-scale fermentation experience. In order to verify the malic acid production potential, two wild-type strains, NRRL3485 and NRRL3488, were compared in shake flasks. As NRRL3488 showed a volumetric production rate twice as high as that of NRRL3485, this strain was selected for further investigation of the influence of two different nitrogen sources on malic acid secretion. The cultivation in lab-scale fermentors resulted in a higher final titer, 30.27 ± 1.05 g liter−1, using peptone than the one of 22.27 ± 0.46 g liter−1obtained when ammonium was used. Through transcriptome analysis, a binding site similar to the one of theSaccharomyces cerevisiaeyeast transcription factor Msn2/4 was identified in the upstream regions of glycolytic genes and the cytosolic malic acid production pathway from pyruvate via oxaloacetate to malate, which suggests that malic acid production is a stress response. Furthermore, the pyruvate carboxylase reaction was identified as a target for metabolic engineering, after it was confirmed to be transcriptionally regulated through the correlation of intracellular fluxes and transcriptional changes.


2014 ◽  
Vol 80 (19) ◽  
pp. 6212-6222 ◽  
Author(s):  
Jun Min ◽  
Jun-Jie Zhang ◽  
Ning-Yi Zhou

ABSTRACTBurkholderiasp. strain SJ98 (DSM 23195) utilizes 2-chloro-4-nitrophenol (2C4NP) orpara-nitrophenol (PNP) as a sole source of carbon and energy. Here, by genetic and biochemical analyses, a 2C4NP catabolic pathway different from those of all other 2C4NP utilizers was identified with chloro-1,4-benzoquinone (CBQ) as an intermediate. Reverse transcription-PCR analysis showed that all of thepnpgenes in thepnpABA1CDEFcluster were located in a single operon, which is significantly different from the genetic organization of all other previously reported PNP degradation gene clusters, in which the structural genes were located in three different operons. All of the Pnp proteins were purified to homogeneity as His-tagged proteins. PnpA, a PNP 4-monooxygenase, was found to be able to catalyze the monooxygenation of 2C4NP to CBQ. PnpB, a 1,4-benzoquinone reductase, has the ability to catalyze the reduction of CBQ to chlorohydroquinone. Moreover, PnpB is also able to enhance PnpA activityin vitroin the conversion of 2C4NP to CBQ. Genetic analyses indicated thatpnpAplays an essential role in the degradation of both 2C4NP and PNP by gene knockout and complementation. In addition to being responsible for the lower pathway of PNP catabolism, PnpCD, PnpE, and PnpF were also found to be likely involved in that of 2C4NP catabolism. These results indicated that the catabolism of 2C4NP and that of PNP share the same gene cluster in strain SJ98. These findings fill a gap in our understanding of the microbial degradation of 2C4NP at the molecular and biochemical levels.


2015 ◽  
Vol 197 (24) ◽  
pp. 3788-3796 ◽  
Author(s):  
Takayuki Kuge ◽  
Haruhiko Teramoto ◽  
Masayuki Inui

ABSTRACTInCorynebacterium glutamicumATCC 31831, a LacI-type transcriptional regulator AraR, represses the expression ofl-arabinose catabolism (araBDA), uptake (araE), and the regulator (araR) genes clustered on the chromosome. AraR binds to three sites: one (BSB) between the divergent operons (araBDAandgalM-araR) and two (BSE1and BSE2) upstream ofaraE.l-Arabinose acts as an inducer of the AraR-mediated regulation. Here, we examined the roles of these AraR-binding sites in the expression of the AraR regulon. BSBmutation resulted in derepression of botharaBDAandgalM-araRoperons. The effects of BSE1and/or BSE2mutation onaraEexpression revealed that the two sites independently function as theciselements, but BSE1plays the primary role. However, AraR was shown to bind to these sites with almost the same affinityin vitro. Taken together, the expression ofaraBDAandaraEis strongly repressed by binding of AraR to a single site immediately downstream of the respective transcriptional start sites, whereas the binding site overlapping the −10 or −35 region of thegalM-araRandaraEpromoters is less effective in repression. Furthermore, downregulation ofaraBDAandaraEdependent onl-arabinose catabolism observed in the BSBmutant and the AraR-independentaraRpromoter identified withingalM-araRadd complexity to regulation of the AraR regulon derepressed byl-arabinose.IMPORTANCECorynebacterium glutamicumhas a long history as an industrial workhorse for large-scale production of amino acids. An important aspect of industrial microorganisms is the utilization of the broad range of sugars for cell growth and production process. MostC. glutamicumstrains are unable to use a pentose sugarl-arabinose as a carbon source. However, genes forl-arabinose utilization and its regulation have been recently identified inC. glutamicumATCC 31831. This study elucidates the roles of the multiple binding sites of the transcriptional repressor AraR in the derepression byl-arabinose and thereby highlights the complex regulatory feedback loops in combination withl-arabinose catabolism-dependent repression of the AraR regulon in an AraR-independent manner.


2015 ◽  
Vol 82 (4) ◽  
pp. 1050-1059 ◽  
Author(s):  
Zhao Jin ◽  
Sara C. Di Rienzi ◽  
Anders Janzon ◽  
Jeff J. Werner ◽  
Largus T. Angenent ◽  
...  

ABSTRACTMetagenomes derived from environmental microbiota encode a vast diversity of protein homologs. How this diversity impacts protein function can be explored through selection assays aimed to optimize function. While artificially generated gene sequence pools are typically used in selection assays, their usage may be limited because of technical or ethical reasons. Here, we investigate an alternative strategy, the use of soil microbial DNA as a starting point. We demonstrate this approach by optimizing the function of a widely occurring soil bacterial enzyme, 1-aminocyclopropane-1-carboxylate (ACC) deaminase. We identified a specific ACC deaminase domain region (ACCD-DR) that, when PCR amplified from the soil, produced a variant pool that we could swap into functional plasmids carrying ACC deaminase-encoding genes. Functional clones of ACC deaminase were selected for in a competition assay based on their capacity to provide nitrogen toEscherichia coliin vitro. The most successful ACCD-DR variants were identified after multiple rounds of selection by sequence analysis. We observed that previously identified essential active-site residues were fixed in the original unselected library and that additional residues went to fixation after selection. We identified a divergent essential residue whose presence hints at the possible use of alternative substrates and a cluster of neutral residues that did not influence ACCD performance. Using an artificial ACCD-DR variant library generated by DNA oligomer synthesis, we validated the same fixation patterns. Our study demonstrates that soil metagenomes are useful starting pools of protein-coding-gene diversity that can be utilized for protein optimization and functional characterization when synthetic libraries are not appropriate.


2016 ◽  
Vol 199 (1) ◽  
Author(s):  
Desmond A. Moore ◽  
Zakiya N. Whatley ◽  
Chandra P. Joshi ◽  
Masaki Osawa ◽  
Harold P. Erickson

ABSTRACT FtsZ, a bacterial tubulin homologue, is a cytoskeletal protein that assembles into protofilaments that are one subunit thick. These protofilaments assemble further to form a “Z ring” at the center of prokaryotic cells. The Z ring generates a constriction force on the inner membrane and also serves as a scaffold to recruit cell wall remodeling proteins for complete cell division in vivo. One model of the Z ring proposes that protofilaments associate via lateral bonds to form ribbons; however, lateral bonds are still only hypothetical. To explore potential lateral bonding sites, we probed the surface of Escherichia coli FtsZ by inserting either small peptides or whole fluorescent proteins (FPs). Among the four lateral surfaces on FtsZ protofilaments, we obtained inserts on the front and back surfaces that were functional for cell division. We concluded that these faces are not sites of essential interactions. Inserts at two sites, G124 and R174, located on the left and right surfaces, completely blocked function, and these sites were identified as possible sites for essential lateral interactions. However, the insert at R174 did not interfere with association of protofilaments into sheets and bundles in vitro. Another goal was to find a location within FtsZ that supported insertion of FP reporter proteins while allowing the FtsZ-FPs to function as the sole source of FtsZ. We discovered one internal site, G55-Q56, where several different FPs could be inserted without impairing function. These FtsZ-FPs may provide advances for imaging Z-ring structure by superresolution techniques. IMPORTANCE One model for the Z-ring structure proposes that protofilaments are assembled into ribbons by lateral bonds between FtsZ subunits. Our study excluded the involvement of the front and back faces of the protofilament in essential interactions in vivo but pointed to two potential lateral bond sites, on the right and left sides. We also identified an FtsZ loop where various fluorescent proteins could be inserted without blocking function; these FtsZ-FPs functioned as the sole source of FtsZ. This advance provides improved tools for all fluorescence imaging of the Z ring and may be especially important for superresolution imaging.


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