Cloning, reassembling and integration of the entire nikkomycin biosynthetic gene cluster into Streptomyces ansochromogenes lead to an improved nikkomycin production

<p>Abstract</p> <p>Background</p> <p>Nikkomycins are a group of peptidyl nucleoside antibiotics produced by <it>Streptomyces ansochromogenes</it>. They are competitive inhibitors of chitin synthase and show potent fungicidal, insecticidal, and acaricidal activities. Nikkomycin X and Z are the main components produced by <it>S. ansochromogenes</it>. Generation of a high-producing strain is crucial to scale up nikkomycins production for further clinical trials.</p> <p>Results</p> <p>To increase the yields of nikkomycins, an additional copy of nikkomycin biosynthetic gene cluster (35 kb) was introduced into nikkomycin producing strain, <it>S. ansochromogenes </it>7100. The gene cluster was first reassembled into an integrative plasmid by Red/ET technology combining with classic cloning methods and then the resulting plasmid(pNIK)was introduced into <it>S. ansochromogenes </it>by conjugal transfer. Introduction of pNIK led to enhanced production of nikkomycins (880 mg L^-1, 4 -fold nikkomycin X and 210 mg L^-1, 1.8-fold nikkomycin Z) in the resulting exconjugants comparing with the parent strain (220 mg L^-1nikkomycin X and 120 mg L^-1nikkomycin Z). The exconjugants are genetically stable in the absence of antibiotic resistance selection pressure.</p> <p>Conclusion</p> <p>A high nikkomycins producing strain (1100 mg L^-1nikkomycins) was obtained by introduction of an extra nikkomycin biosynthetic gene cluster into the genome of <it>S. ansochromogenes</it>. The strategies presented here could be applicable to other bacteria to improve the yields of secondary metabolites.</p

Selectively improving nikkomycin Z production by blocking the imidazolone biosynthetic pathway of nikkomycin X and uracil feeding in Streptomyces ansochromogenes

<p>Abstract</p> <p>Background</p> <p>Nikkomycins are a group of peptidyl nucleoside antibiotics and act as potent inhibitors of chitin synthases in fungi and insects. Nikkomycin X and Z are the main components produced by <it>Streptomyces ansochromogenes</it>. Of them, nikkomycin Z is a promising antifungal agent with clinical significance. Since highly structural similarities between nikkomycin Z and X, separation of nikkomycin Z from the culture medium of <it>S. ansochromogenes </it>is difficult. Thus, generating a nikkomycin Z selectively producing strain is vital to scale up the nikkomycin Z yields for clinical trials.</p> <p>Results</p> <p>A nikkomycin Z producing strain (sanPDM) was constructed by blocking the imidazolone biosynthetic pathway of nikkomycin X via genetic manipulation and yielded 300 mg/L nikkomycin Z and abolished the nikkomycin X production. To further increase the yield of nikkomycin Z, the effects of different precursors on its production were investigated. Precursors of nucleoside moiety (uracil or uridine) had a stimulatory effect on nikkomycin Z production while precursors of peptidyl moiety (L-lysine and L-glutamate) had no effect. sanPDM produced the maximum yields of nikkomycin Z (800 mg/L) in the presence of uracil at the concentration of 2 g/L and it was approximately 2.6-fold higher than that of the parent strain.</p> <p>Conclusion</p> <p>A high nikkomycin Z selectively producing was obtained by genetic manipulation combined with precursors feeding. The strategy presented here might be applicable in other bacteria to selectively produce targeted antibiotics.</p

A critical role for hepatic protein arginine methyltransferase 1 isoform 2 in glycemic control

Appropriate control of hepatic gluconeogenesis is essential for the organismal survival upon prolonged fasting and maintaining systemic homeostasis under metabolic stress. Here, we show protein arginine methyltransferase 1 (PRMT1), a key enzyme that catalyzes the protein arginine methylation process, particularly the isoform encoded by Prmt1 variant 2 (PRMT1V2), is critical in regulating gluconeogenesis in the liver. Liver‐specific deletion of Prmt1 reduced gluconeogenic capacity in cultured hepatocytes and in the liver. Prmt1v2 was expressed at a higher level compared to Prmt1v1 in hepatic tissue and cells. Gain‐of‐function of PRMT1V2 clearly activated the gluconeogenic program in hepatocytes via interactions with PGC1α, a key transcriptional coactivator regulating gluconeogenesis, enhancing its activity via arginine methylation, while no effects of PRMT1V1 were observed. Similar stimulatory effects of PRMT1V2 in controlling gluconeogenesis were observed in human HepG2 cells. PRMT1, specifically PRMT1V2, was stabilized in fasted liver and hepatocytes treated with glucagon, in a PGC1α‐dependent manner. PRMT1, particularly Prmt1v2, was significantly induced in the liver of streptozocin‐induced type 1 diabetes and high fat diet‐induced type 2 diabetes mouse models and liver‐specific Prmt1 deficiency drastically ameliorated diabetic hyperglycemia. These findings reveal that PRMT1 modulates gluconeogenesis and mediates glucose homeostasis under physiological and pathological conditions, suggesting that deeper understanding how PRMT1 contributes to the coordinated efforts in glycemic control may ultimately present novel therapeutic strategies that counteracts hyperglycemia in disease settings.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/163465/10/fsb221018-sup-0005-FigS5.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/163465/9/fsb221018-sup-0001-FigS1.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/163465/8/fsb221018-sup-0003-FigS3.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/163465/7/fsb221018-sup-0008-FigS8.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/163465/6/fsb221018-sup-0002-FigS2.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/163465/5/fsb221018_am.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/163465/4/fsb221018.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/163465/3/fsb221018-sup-0007-FigS7.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/163465/2/fsb221018-sup-0006-FigS6.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/163465/1/fsb221018-sup-0004-FigS4.pd

SMPKR : search engine for Internet of Things

The Internet of Things (IoT) has become the infrastructure to widely support ubiquitous applications. Due to the highly dynamic context setting, IoT search engines have attracted increasing attention from both industrial and academic field to crawl and search heterogeneous data sources. Today, a large amount of work on IoT search engines is devoted to finding a particular mobile object device, or a group of object devices satisfying the constraint on query terms description. However, it still lacks studies on enabling so-called spatial-temporal-keyword-aware query. Only a few research work simply applies a keyword or spatial-temporal matching to identify object devices. In this case, it is insufficient to simultaneously consider the spatial-temporal-keyword aspect in order to satisfy the user request. To address this challenge, we develop a new search mechanism over PKR-tree (denoted SMPKR), in which PKR-tree unifiedly integrates spatial-temporal-keyword proximity with the help of a coding enabled index. Efficient algorithms are developed for answering range and (enhanced) KNN queries. Extensive experimental results demonstrate that our SMPKR search engine promotes the efficiency of searching for object devices with spatial-temporal-keyword constraints in comparison with the state of arts.The National Natural Science Foundation of China and the Science and Technology Planning Project of Guangdong Province.http://ieeexplore.ieee.org/xpl/RecentIssue.jsp?punumber=6287639am2020Electrical, Electronic and Computer Engineerin

Novel polyoxins generated by heterologously expressing polyoxin biosynthetic gene cluster in the <it>sanN</it> inactivated mutant of <it>Streptomyces ansochromogenes</it>

Abstract Background Polyoxins are potent inhibitors of chitin synthetases in fungi and insects. The gene cluster responsible for biosynthesis of polyoxins has been cloned and sequenced from Streptomyces cacaoi and tens of polyoxin analogs have been identified already. Results The polyoxin biosynthetic gene cluster from Streptomyces cacaoi was heterologously expressed in the sanN inactivated mutant of Streptomyces ansochromogenes as a nikkomycin producer. Besides hybrid antibiotics (polynik A and polyoxin N) and some known polyoxins, two novel polyoxin analogs were accumulated. One of them is polyoxin P that has 5-aminohexuronic acid with N-glycosidically bound thymine as the nucleoside moiety and dehydroxyl-carbamoylpolyoxic acid as the peptidyl moiety. The other analog is polyoxin O that contains 5-aminohexuronic acid bound thymine as the nucleoside moiety, but recruits polyoximic acid as the sole peptidyl moiety. Bioassay against phytopathogenic fungi showed that polyoxin P displayed comparatively strong inhibitory activity, whereas the inhibitory activity of polyoxin O was weak under the same testing conditions. Conclusion Two novel polyoxin analogs (polyoxin P and O) were generated by the heterologous expression of polyoxin biosynthetic gene cluster in the sanN inactivated mutant of Streptomyces ansochromogenes. Polyoxin P showed potent antifungal activity,while the activity of polyoxin O was weak. The strategy presented here may be available for other antibiotics producers.</p

Microbial Predominance and Antimicrobial Resistance in a Tertiary Hospital in Northwest China: A Six-Year Retrospective Study of Outpatients and Patients Visiting the Emergency Department

Background. With the wide use of antibiotics, antimicrobial resistance becomes a serious issue. Timely understanding of microbial pathogen profiles and the change of antimicrobial resistance provide an important guidance for effective and optimized use of antibiotics in local healthcare systems. The aim was to investigate the characteristics of microbial species and their antimicrobial resistances in a tertiary hospital with an Emergency Department and outpatient clinics for a period of six years. Methodology. A retrospective study was conducted using the HIS database of a tertiary hospital between 2013 and 2018. Antimicrobial susceptibility was tested by automated systems and/or the Kirby–Bauer disc diffusion method. The data were analyzed using the WHONET 5.6 software. The Cochran-Armitage test was used to study the trends over the period of research. Results. In a total of 19,028 specimens submitted for microbial tests during the period from 49 units of the hospital, only the samples from the Emergency Department and Kidney Transplantation Clinic showed an annually significant increase (P<0.001). More than 200 species with 46.4% gram-positive cocci and 45.3% gram-negative bacilli were identified in the 3,849 nonrepetitive isolates. The methicillin-resistant S. aureus and S. epidermidis rates were 25.1% and 74.6%, respectively. 60.9% E. coli and 33.5% K. pneumonia samples carried extended-spectrum-β-lactamase. All Staphylococci and Enterococci samples were not resistant to linezolid, vancomycin, and tigecycline. In addition, only 0.01% E. coli, 1.1% K. pneumonia, and 18.7% P. aeruginosa isolates showed resistance to carbapenems. Conclusions. Vancomycin, linezolid and tigecycline were the most effective antibiotics for outpatients with gram-positive infection. Carbapenems were the most effective antibiotics for gram-negative infection. There was no significant annual increase of common multidrug resistances