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Eirik Adim Moreb, Benjamin Hoover, Adam Yaseen, Nisakorn Valyasevi, Zoe Roecker, Romel Menacho-Melgar, Michael Lynch
Phage-derived "recombineering" methods are utilized for bacterial genome editing. Recombineering results in a heterogeneous population of modified and unmodified chromosomes and therefore selection methods, such as CRISPR-Cas9, are required to select for edited clones. Cells can evade CRISPR-Cas-induced cell death through recA-mediated induction of the SOS response. The SOS response increases RecA dependent repair as well mutation rates through the induction of the umuDC error prone polymerase. As a result, CRISPR-Cas selection is more efficient in recA mutants...
September 15, 2017: ACS Synthetic Biology
Sung Hyun Kim, TakKyoon Ahn, Tao Ju Cui, Sweeny Chauhan, Jaeyoung Sung, Chirlmin Joo, Doseok Kim
At the core of homologous DNA repair, RecA catalyzes the strand exchange reaction. This process is initiated by a RecA loading protein, which nucleates clusters of RecA proteins on single-stranded DNA. Each cluster grows to cover the single-stranded DNA but may leave 1- to 2-nucleotide (nt) gaps between the clusters due to three different structural phases of the nucleoprotein filaments. It remains to be revealed how RecA proteins eliminate the gaps to make a seamless kilobase-long filament. We develop a single-molecule fluorescence assay to observe the novel internal dynamics of the RecA filament...
September 2017: Science Advances
Shimin Le, Ester Serrano, Ryo Kawamura, Begoña Carrasco, Jie Yan, Juan C Alonso
Bacillus subtilis DprA and RecX proteins, which interact with RecA, are crucial for efficient chromosomal and plasmid transformation. We showed that RecA, in the rATP·Mg2+ bound form (RecA·ATP), could not compete with RecX, SsbA or SsbB for assembly onto single-stranded (ss)DNA, but RecA·dATP partially displaced these proteins from ssDNA. RecX promoted reversible depolymerization of preformed RecA·ATP filaments. The two-component DprA-SsbA mediator reversed the RecX negative effect on RecA filament extension, but not DprA or DprA and SsbB...
September 6, 2017: Nucleic Acids Research
Rodica C Efrose, Craita M Rosu, Catalina Stedel, Andrei Stefan, Culita Sirbu, Lucian D Gorgan, Nikolaos E Labrou, Emmanouil Flemetakis
The symbiotic nitrogen fixing legumes play an essential role in sustainable agriculture. White clover (Trifolium repens L.) is one of the most valuable perennial legumes in pastures and meadows of temperate regions. Despite its great agriculture and economic importance, there is no detailed available information on phylogenetic assignation and characterization of rhizobia associated with native white clover plants in South-Eastern Europe. In the present work, the diversity of indigenous white clover rhizobia originating in 11 different natural ecosystems in North-Eastern Romania were assessed by a polyphasic approach...
September 13, 2017: Antonie Van Leeuwenhoek
Andrey Barbosa Cordeiro, Renan Augusto Ribeiro, Luisa Caroline Ferraz Helene, Mariangela Hungria
Common bean (Phaseolus vulgaris L.) is the most important legume consumed worldwide; its genetic origins lie in the Mesoamerican (main centre) and Andean regions. It is promiscuous in establishing root-nodule symbioses; however, in the centres of origin/domestication, the predominant association is with Rhizobium etli. We have previously identified a new lineage (PEL-3) comprising three strains (CNPSo 661, CNPSo 666 and CNPSo 668T) isolated from root nodules of common bean in Mexico, and that have now been analysed in more detail...
September 12, 2017: International Journal of Systematic and Evolutionary Microbiology
Lohengrin Dias de Almeida Fernandes, Eduardo Barros Fagundes Netto, Ricardo Coutinho
Currently, spatial and temporal changes in nutrients availability, marine planktonic, and fish communities are best described on a shorter than inter-annual (seasonal) scale, primarily because the simultaneous year-to-year variations in physical, chemical, and biological parameters are very complex. The limited availability of time series datasets furnishing simultaneous evaluations of temperature, nutrients, plankton, and fish have limited our ability to describe and to predict variability related to short-term process, as species-specific phenology and environmental seasonality...
2017: PloS One
Anna Hegyi, Mónika Szabó, Ferenc Olasz, János Kiss
Dissemination of multiresistance has been accelerating among pathogenic bacteria in recent decades. The broad host-range conjugative plasmids of the IncA/C family are effective vehicles of resistance determinants in Gram-negative bacteria. Although more than 150 family members have been sequenced to date, their conjugation system and other functions encoded by the conserved plasmid backbone have been poorly characterized. The key cis-acting locus, the origin of transfer (oriT), has not yet been unambiguously identified...
September 6, 2017: Scientific Reports
Hassan Z A Ishag, Qiyan Xiong, Maojun Liu, Zhixin Feng, Guoqing Shao
Mycoplasma hyorhinis (M. hyorhinis) is an opportunistic pig pathogen, belonging to the class Mollicutes. It causes polyserositis, arthritis and cancers in vitro, increasing attention of the researchers. Currently, there is no available genetic tool to manipulate its genome. This study describes a development of oriC-plasmids harboring either large (pGEMT-LoriC) or minimum (pGEMT-MoriC) origin of replication (oriC) of M. hyorhinis along with tetracycline resistance marker.These plasmids were successfully transformed into M...
September 6, 2017: Scientific Reports
Eden S P Bromfield, Sylvie Cloutier, James T Tambong, Thu Van Tran Thi
An assessment was made of the evolutionary relationships of soybean nodulating bacteria associated with legumes native to eastern Canada to identify potential new sources of soybean inoculant strains. Short season soybeans were used to selectively trap bacteria from root zone soils of four native legume species. Screening of more than 800 bacterial isolates from soybean root nodules by analysis of recA gene sequences followed by analyses of selected genotypes using six core and two symbiosis (nodC and nifH) gene sequences permitted identification of diverse taxa that included eight novel and four named Bradyrhizobium species as well as lineages attributed to the genera Afipia and Tardiphaga...
August 18, 2017: Systematic and Applied Microbiology
Hamida Beghalem, Khadidja Aliliche, Ali Chriki, Ahmed Landoulsi
In the current study, bacterial diversity was investigated in root nodules of Sulla pallida and Sulla capitata. The isolates were analyzed on the basis of their phenotypic and molecular characteristics. The phylogenetic analysis based on 16S rRNA and housekeeping genes (recA and atpD) showed that the isolated bacteria related to Sinorhizobium, Neorhizobium, Phyllobacterium, Arthrobacter, Variovorax and Pseudomonas genera. This is the first report of Neorhizobium genus associated with Hedysarum genus. Phenotypically, all strains tolerate the elevated temperature of 40 °C, and salt stress at a concentration of 2%...
September 1, 2017: Microbial Pathogenesis
Ki Wook Yun, Mi-Kyung Lee, Wonyong Kim, In Seok Lim
PURPOSE: Escherichia coli sequence type (ST) 131, a multidrug-resistant clone causing extraintestinal infections, has rapidly become prevalent worldwide. However, the epidemiological and clinical features of pediatric infections are poorly understood. We aimed to explore the characteristics of ST131 Escherichia coli isolated from Korean children with urinary tract infections. METHODS: We examined 114 uropathogenic E. coli (UPEC) isolates from children hospitalized at Chung-Ang University Hospital between 2011 and 2014...
July 2017: Korean Journal of Pediatrics
Evelise Bach, Fernando Hayashi Sant'Anna, João Frederico Magrich Dos Passos, Eduardo Balsanelli, Valter Antonio de Baura, Fábio de Oliveira Pedrosa, Emanuel Maltempi de Souza, Luciane Maria Pereira Passaglia
The correct identification of bacteria from the Burkholderia cepacia complex (Bcc) is crucial for epidemiological studies and treatment of cystic fibrosis infections. However, genome-based identification tools are revealing many controversial Bcc species assignments. The aim of this work is to re-examine the taxonomic position of the soil bacterium B. cepacia 89 through polyphasic and genomic approaches. recA and 16S rRNA gene sequence analysis positioned strain 89 inside the Bcc group. However, based on the divergence score of seven concatenated allele sequences, and values of average nucleotide identity, and digital DNA:DNA hybridization, our results suggest that strain 89 is different from other Bcc species formerly described...
August 31, 2017: Pathogens and Disease
Hanako Fukano, Shinpei Wada, Osamu Kurata, Kinya Katayama, Nagatoshi Fujiwara, Yoshihiko Hoshino
A previously undescribed rapidly growing, non-pigmented mycobacterium was identified based on biochemical and nucleic acid analyses, as well as growth characteristics. Seven isolates were cultured from samples collected from five thread-sail filefish (Stephanolepis cirrhifer) and two farmed black scraper (Thamnaconus modestus). Bacterial growth occurred at 15-35 °C on Middlebrook 7H11 agar. The bacteria were positive for catalase activity at 68 °C and urease activity, intermediate for iron uptake, and negative for Tween 80 hydrolysis, nitrate reduction, semi-quantitative catalase activity and arylsulfatase activity at day 3...
August 2017: International Journal of Systematic and Evolutionary Microbiology
Paul R Meyers
The genera Microbispora and Sphaerimonospora were examined for GyrB and RecA amino-acid signatures to determine whether molecular-signature analyses support the recent establishment of the genus Sphaerimonospora. The creation of Sphaerimonospora was based mainly upon morphological differences between Microbispora and Sphaerimonospora and the clustering of the type strains of the two genera in phylogenetic trees based on a multilocus sequence analysis. The molecular-signature analyses showed that all members of Sphaerimonospora can be distinguished from all members of Microbispora at 14 amino acid positions in the GyrB protein and at four positions in the shorter RecA protein...
August 18, 2017: Systematic and Applied Microbiology
Claudia Danilowicz, Laura Hermans, Vincent Coljee, Chantal Prévost, Mara Prentiss
During DNA recombination and repair, RecA family proteins must promote rapid joining of homologous DNA. Repeated sequences with >100 base pair lengths occupy more than 1% of bacterial genomes; however, commitment to strand exchange was believed to occur after testing ∼20-30 bp. If that were true, pairings between different copies of long repeated sequences would usually become irreversible. Our experiments reveal that in the presence of ATP hydrolysis even 75 bp sequence-matched strand exchange products remain quite reversible...
August 21, 2017: Nucleic Acids Research
Ge-Yi Fu, Xiao-Yun Yu, Chong-Ya Zhang, Zhe Zhao, Dildar Wu, Yue Su, Rui-Jun Wang, Shuai-Bo Han, Min Wu, Cong Sun
A novel Gram-staining-negative, oval-shaped (0.4-0.6×0.8-1.0 µm), non-motile strain without flagella, designated B7T, was isolated from deep seawater in the South China Sea. Strain B7T was able to grow at 25-40 °C (optimum 35 °C), at pH 5.5-9.0 (optimum pH 7.0) and with 0-8 % (w/v) NaCl (optimum 3 %). Chemotaxonomic analysis showed that the predominant isoprenoid quinone was Q-10 and the dominant fatty acids were C19 : 0 cyclo 8c and summed feature 8 (C18 : 1ω7c/C18 : 1ω6c). The polar lipids of strain B7T were diphosphatidyglycerol, phosphatidylglycerol, phosphatidylethanolamine, phosphatidylcholine, one unknown aminophospholipid, one unknown glycolipid and three unknown lipids...
August 2017: International Journal of Systematic and Evolutionary Microbiology
Fan Xia, Mei-Hong Chen, Ying-Ying Lv, Han-Yun Zhang, Li-Hong Qiu
Three strains, DHOB09T, DHOC52T and DHON07T, were isolated from the forest soil of Dinghushan Biosphere Reserve, Guangdong Province, PR China. They were all Gram-stain-negative, aerobic, rod-shaped cells. The ranges (optimum) for the temperature, pH and NaCl concentration for growth of DHOB09T, DHOC52T and DHON07T were 10-42 (25-28) °C, pH 5.5-9.0 (7.0-7.5) and 0-4.0 (0-0.5) % (w/v); 10-42 (28) °C, pH 4.0-7.0 (4.5-6.5) and 0-2.0 (0) % (w/v) and 10-37 (25-28) °C, pH 4.0-7.5 (5.5-6.0) and 0-2.5 (0)  % (w/v), respectively...
September 2017: International Journal of Systematic and Evolutionary Microbiology
Faqing Huang, Joseph Rankin Spangler, Allen Yang Huang
The precise assembly of defined DNA sequences into plasmids is an essential task in bioscience research. While a number of molecular cloning techniques have been developed, many methods require specialized expensive reagents or laborious experimental procedure. Not surprisingly, conventional cloning techniques based on restriction digestion and ligation are still commonly used in routine DNA cloning. Here, we describe a simple, fast, and economical cloning method based on RecA- and RecET-independent in vivo recombination of DNA fragments with overlapping ends using E...
2017: PloS One
John L Kulp, Ian S Cloudsdale, John L Kulp, Frank Guarnieri
Chemically diverse fragments tend to collectively bind at localized sites on proteins, which is a cornerstone of fragment-based techniques. A central question is how general are these strategies for predicting a wide variety of molecular interactions such as small molecule-protein, protein-protein and protein-nucleic acid for both experimental and computational methods. To address this issue, we recently proposed three governing principles, (1) accurate prediction of fragment-macromolecule binding free energy, (2) accurate prediction of water-macromolecule binding free energy, and (3) locating sites on a macromolecule that have high affinity for a diversity of fragments and low affinity for water...
2017: PloS One
Jeffrey M Kubiak, Matthew J Culyba, Monica Yun Liu, Charlie Y Mo, Mark Goulian, Rahul M Kohli
The bacterial SOS stress-response pathway is a pro-mutagenic DNA repair system that mediates bacterial survival and adaptation to genotoxic stressors, including antibiotics and UV light. The SOS pathway is composed of a network of genes under the control of the transcriptional repressor, LexA. Activation of the pathway involves linked but distinct events: an initial DNA damage event leads to activation of RecA, which promotes auto-proteolysis of LexA, abrogating its repressor function and leading to induction of the SOS gene network...
August 21, 2017: ACS Synthetic Biology
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