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Applied and Environmental Microbiology Feb 2023Site-specific recombinases (integrases) can mediate the horizontal transfer of genomic islands. The ability to integrate large DNA sequences into target sites is very...
Site-specific recombinases (integrases) can mediate the horizontal transfer of genomic islands. The ability to integrate large DNA sequences into target sites is very important for genetic engineering in prokaryotic and eukaryotic cells. Here, we characterized an unprecedented catalogue of 530 tyrosine-type integrases by examining genes potentially encoding tyrosine integrases in bacterial genomic islands. The phylogeny of putative tyrosine integrases revealed that these integrases form an evolutionary clade that is distinct from those already known and are affiliated with novel integrase groups. We systematically searched for candidate integrase genes, and their integration activities were validated in a bacterial model. We verified the integration functions of six representative novel integrases by using a two-plasmid integration system consisting of a donor plasmid carrying the integrase gene and site and a recipient plasmid harboring an site in -deficient Escherichia coli. Further quantitative reverse transcription-PCR (qRT-PCR) assays validated that the six selected integrases can be expressed with their native promoters in E. coli. The region reductions showed that the extent of sites of integrases is approximately 200 bp for integration capacity. In addition, mutational analysis showed that the conserved tyrosine at the C terminus is essential for catalysis, confirming that these candidate proteins belong to the tyrosine-type recombinase superfamily, i.e., tyrosine integrases. This study revealed that the novel integrases from bacterial genomic islands have site-specific recombination functions, which is of physiological significance for their genomic islands in bacterial chromosomes. More importantly, our discovery expands the toolbox for genetic engineering, especially for efficient integration activity. Site-specific recombinases or integrases have high specificity for DNA large fragment integration, which is urgently needed for gene editing. However, known integrases are not sufficient for meeting multiple integrations. In this work, we discovered an array of integrases through bioinformatics analysis in bacterial genomes. Phylogeny and functional assays revealed that these new integrases belong to tyrosine-type integrases and have the ability to conduct site-specific recombination. Moreover, region extent and catalysis site analysis were characterized. Our study provides the methodology for discovery of novel integrases and increases the capacity of weapon pool for genetic engineering in bacteria.
Topics: Integrases; Genomic Islands; Escherichia coli; Tyrosine; Plasmids; Bacteriophages; Attachment Sites, Microbiological
PubMed: 36719242
DOI: 10.1128/aem.01738-22 -
International Journal of Molecular... Jan 2022Human endogenous retroviruses (HERVs) are remnants of ancient retroviral infections that have become fixed in the human genome. While HERV genes are typically silenced...
Human endogenous retroviruses (HERVs) are remnants of ancient retroviral infections that have become fixed in the human genome. While HERV genes are typically silenced in healthy somatic cells, there are numerous reports of HERV transcription and translation across a wide spectrum of cancers, while T and B cell responses against HERV proteins have been detected in cancer patients. This review systematically categorizes the published evidence on the expression of and adaptive immune response against specific HERVs in distinct cancer types. A systematic literature search was performed using Medical Search Headings (MeSH) in the PubMed/Medline database. Papers were included if they described the translational activity of HERVs. We present multiple tables that pair the protein expression of specific HERVs and cancer types with information on the quality of the evidence. We find that HERV-K is the most investigated HERV. HERV-W (syncytin-1) is the second-most investigated, while other HERVs have received less attention. From a therapeutic perspective, HERV-K and HERV-E are the only HERVs with experimental demonstration of effective targeted therapies, but unspecific approaches using antiviral and demethylating agents in combination with chemo- and immunotherapies have also been investigated.
Topics: Animals; Antibody Formation; Endogenous Retroviruses; Host-Pathogen Interactions; Humans; Neoplasms; Retroviridae Infections; Viral Proteins
PubMed: 35163254
DOI: 10.3390/ijms23031330 -
The Journal of Surgical Research Aug 2019Human endogenous retroviruses (HERVs) are genetic elements in the human genome, which resulted from ancient retroviral germline infections. HERVs have strong...
BACKGROUND
Human endogenous retroviruses (HERVs) are genetic elements in the human genome, which resulted from ancient retroviral germline infections. HERVs have strong transcriptional promoters and enhancers that affect a cell's transcriptome. They also encode proteins that can exert effects in human cells. This review examines how our increased understanding of HERVs have led to their potential use as biomarkers and immunologic targets.
MATERIAL AND METHODS
PubMed/Medline, Embase, Web of Science, and Cochrane databases were used in a systematic search to identify all articles studying the potential impact of HERVs on surgical diseases. The search included studies that involved clinical patient samples in diseases including cancer, inflammatory conditions, and autoimmune disease. Articles focused on conditions not routinely managed by surgeons were excluded.
RESULTS
Eighty six articles met inclusion and quality criteria for this review and were included. Breast cancer and melanoma have robust evidence regarding the use of HERVs as potential tumor markers and immunologic targets. Reported evidence of the activity of HERVs in colorectal cancer, pancreatic cancer, hepatocellular cancer, prostate and ovarian cancer, germ cell tumors as well as idiopathic pulmonary hypertension, and the inflammatory response in burns was also reviewed.
CONCLUSIONS
Increasingly convincing evidence indicates that HERVs may play a role in solid organ malignancy and present important biomarkers or immunologic targets in multiple cancers. Innovative investigation of HERVs is a valuable focus of translational research and can deepen our understanding of cellular physiology and the effects of endogenous retroviruses on human biology. As strategies for treatment continue to focus on genome-based interventions, understanding the impact of endogenous retroviruses on human disease will be critical.
Topics: Antineoplastic Agents, Immunological; Biomarkers, Tumor; Endogenous Retroviruses; Gene Expression Regulation, Neoplastic; Genome, Human; Humans; Neoplasms; Transcriptome; Translational Research, Biomedical
PubMed: 30933828
DOI: 10.1016/j.jss.2019.02.009 -
Ethiopian Journal of Health Sciences Sep 2019Acinetobacter baumannii is an important opportunistic nosocomial pathogen. Class 1 integrons in A. baumannii plays a significant role in antibiotic resistance.... (Meta-Analysis)
Meta-Analysis
BACKGROUND
Acinetobacter baumannii is an important opportunistic nosocomial pathogen. Class 1 integrons in A. baumannii plays a significant role in antibiotic resistance. Therefore, this study aimed to investigate the prevalence of integrons and antibiotic resistance pattern in A. baumannii isolated from clinical samples of Iranian patients.
METHODS
The Medical Subject Headings (MeSH) and the keywords with the help of Boolean operators ("AND" or "OR") were used alone or in combination to conduct the search. The searching process was conducted in the Web of Science, PubMed, Cochrane Library, Scopus, and Google Scholar databases and, also Iranian databases. The search was restricted to relevant English and Persian cross-sectional publications reporting the prevalence of Int1 in A. baumannii isolated from clinical samples from 1 January 2000 to 31 December 2018. The data were analyzed using Comprehensive Meta-Analysis software. Regarding the heterogeneity of studies, the random effects model was used. Cochrane Q and I tests was used to evaluate statistical heterogeneity between the studies.
RESULTS
Fifteen studies were included in the analysis. The combined prevalence of class 1 integrons in A. baumannii was 55.2% (95% CI: 44.8-65.1). The pooled prevalence of MDR A. baumannii isolates was 68.1%. The highest resistance belonged to Aztreonam, followed by Ciprofloxacin, and Ceftazidime with a resistance rate of 97.6%, 92.8%, and 91.6%, respectively. Tobramycin was reported as an effective antibiotic.
CONCLUSIONS
The present study reported an alarmingly high prevalence of class 1 Integrons, and MDR isolates of A. baumannii recovered from clinical samples that should be considered.
Topics: Acinetobacter Infections; Acinetobacter baumannii; Anti-Bacterial Agents; Drug Resistance, Multiple, Bacterial; Humans; Integrons; Iran; Microbial Sensitivity Tests; Prevalence
PubMed: 31666786
DOI: 10.4314/ejhs.v29i5.15