Internal translation initiation in the mRNA for the Neurospora crassa albino-3 gene

The "ribosome scanning model" for translational initiation predicts that eukaryotic mRNAs should, as a rule, be monocistronic. However, cases have recently been described of eukaryotic mRNAs producing more than one protein through alternative translational initiation at several different AUG codons. The present work reports the occurrence of multiple translational start sites on the mRNA of the Neurospora crassa gene albino-3 (al-3), encoding the carotenoid biosynthetic enzyme geranylgeranyl-pyrophosphate synthase. This was revealed by the molecular analysis of an al-3 mutant carrying a deletion within the coding sequence, which was expected to prevent the synthesis of a functional geranylgeranyl-pyrophosphate synthase because of ribosome frameshifting and premature translational termination. However, the mutants could maintain appreciable geranylgeranyl-pyrophosphate synthase activity through a mechanism operating at the translational level, whereby a fraction of ribosomes initiated protein synthesis from either of two internal in-frame AUG codons located downstream of the deletion, thus producing a shortened but still active version of the geranylgeranyl-pyrophosphate synthase. The results presented indicate that the internal AUG codons are recognized mainly or solely by direct ribosome binding rather than by "leaky scanning" from the 5' end of the mRNA.The "ribosome scanning model" for translational initiation predicts that eukaryotic mRNAs should, as a rule, be monocistronic. However, cases have recently been described of eukaryotic mRNAs producing more than one protein through alternative translational initiation at several different AUG codons. The present work reports the occurrence of multiple translational start sites on the mRNA of the Neurospora crassa gene albino-3 (al-3), encoding the carotenoid biosynthetic enzyme geranylgeranyl-pyrophosphate synthase. This was revealed by the molecular analysis of an al-3 mutant carrying a deletion within the coding sequence, which was expected to prevent the synthesis of a functional geranylgeranyl-pyrophosphate synthase because of ribosome frameshifting and premature translational termination. However, the mutants could maintain appreciable geranylgeranyl-pyrophosphate synthase activity through a mechanism operating at the translational level, whereby a fraction of ribosomes initiated protein synthesis from either of two internal in-frame AUG codons located downstream of the deletion, thus producing a shortened but still active version of the geranylgeranyl-pyrophosphate synthase. The results presented indicate that the internal AUG codons are recognized mainly or solely by direct ribosome binding rather than by "leaky scanning" from the 5' end of the mRNA

Expanding drug resistance through integron acquisition by IncFI plasmids of Salmonella enterica Typhimurium.

We conducted a 30-year retrospective analysis of IncFI plasmids from Salmonella enterica serotype Typhimurium. These plasmids have been associated with the emergence of epidemic clones of multidrug-resistant Salmonella. Molecular and genetic evidence indicates that IncFI plasmids are evolving through sequential acquisition of integrons carrying different arrays of antibiotic- resistance genes

Characterization of an IncFII Plasmid Encoding NDM-1 from Escherichia coli ST131

Background: The current spread of the gene encoding the metallo-ß-lactamase NDM-1 in Enterobacteriaceae is linked to a variety of surrounding genetic structures and plasmid scaffolds. Methodology: The whole sequence of plasmid pGUE-NDM carrying the bla NDM-1 gene was determined by high-density pyrosequencing and a genomic comparative analysis with other blaNDM-1-negative IncFII was performed. Principal Findings: Plasmid pGUE-NDM replicating in Escherichia coli confers resistance to many antibiotic molecules including b-lactams, aminoglycosides, trimethoprim, and sulfonamides. It is 87,022 bp in-size and carries the two b-lactamase genes bla NDM-1 and bla OXA-1, together with three aminoglycoside resistance genes aacA4, aadA2, and aacC2. Comparative analysis of the multidrug resistance locus contained a module encompassing the blaNDM-1 gene that is actually conserved among different structures identified in other enterobacterial isolates. This module was constituted by the blaNDM-1 gene, a fragment of insertion sequence ISAba125 and a bleomycin resistance encoding gene. Significance: This is the first characterized bla NDM-1-carrying IncFII-type plasmid. Such association between the bla NDM-1 gene and an IncFII-type plasmid backbone is extremely worrisome considering that this plasmid type is known to sprea

Novel plasmid-mediated colistin resistance mcr-4 gene in Salmonella and Escherichia coli, Italy 2013, Spain and Belgium, 2015 to 2016

A novel mcr colistin resistance gene was identified in a strain of Salmonella enterica, monophasic variant of serovar Typhimurium (4,5,12:i:- ), isolated from a pig at slaughter in Italy in 2013, and in Escherichia coli strains collected during routine diagnostic of postweaning diarrhoea in pigs from Spain and Belgium in 2015 and 2016. Immediate implementation of mcrscreening including this novel gene variant is required for Salmonella and E. coli from humans and food-producing animals in Europe. © 2017, European Centre for Disease Prevention and Control (ECDC). All rights reserved

Meropenem-Vaborbactam as Salvage Therapy for Ceftazidime-Avibactam-, Cefiderocol-Resistant ST-512 Klebsiella pneumoniae-Producing KPC-31, a D179Y Variant of KPC-3

A 68-year-old man had recurrent bacteremia by Klebsiella pneumoniae carbapenemase (KPC)-producing K. pneumoniae resistant to ceftazidime-avibactam and cefiderocol. The sequencing of a target region showed that it harbored a KPC-3 variant enzyme (D179Y; KPC-31), which confers resistance to ceftazidime-avibactam and restores meropenem susceptibility. The patient was successfully treated with meropenem-vaborbactam

Whole-genome characterization of a Shewanella algae strain coharboring blaCTX-M-15 and armA genes on a novel IncC plasmid

no abstract per pubblicazione letter

Genetic environment of the blaKPC-2 gene in a Klebsiella pneumoniae isolate that may have been imported to Russia from Southeast Asia

The nucleotide sequence of a blaKPC-2-harboring plasmid (pKPCAPSS) from Klebsiella pneumoniae ST273 isolated in Saint Petersburg, Russia, from a patient with history of recent travel to Vietnam is presented. This 127,970-bp plasmid possessed both IncFII and IncR replicons. blaKPC-2 was localized on a hypothetical mobile element. This element was flanked by 38-bp inverted Tn3 repeats and included a Tn3-specific transposase gene, macrolide resistance operon (mphA-mrx-mphR), and a fragment of blaTEM with unique polymorphisms. © 2017 American Society for Microbiology. All Rights Reserved

Generation of human antibody fragments recognizing distinct epitopes of the nucleocapsid (N) SARS-CoV protein using a phage display approach

BACKGROUND: Severe acute respiratory syndrome (SARS)-CoV is a newly emerging virus that causes SARS with high mortality rate in infected people. Successful control of the global SARS epidemic will require rapid and sensitive diagnostic tests to monitor its spread, as well as, the development of vaccines and new antiviral compounds including neutralizing antibodies that effectively prevent or treat this disease. METHODS: The human synthetic single-chain fragment variable (scFv) ETH-2 phage antibody library was used for the isolation of scFvs against the nucleocapsid (N) protein of SARS-CoV using a bio panning-based strategy. The selected scFvs were characterized under genetics-molecular aspects and for SARS-CoV N protein detection in ELISA, western blotting and immunocytochemistry. RESULTS: Human scFv antibodies to N protein of SARS-CoV can be easily isolated by selecting the ETH-2 phage library on immunotubes coated with antigen. These in vitro selected human scFvs specifically recognize in ELISA and western blotting studies distinct epitopes in N protein domains and detect in immunohistochemistry investigations SARS-CoV particles in infected Vero cells. CONCLUSION: The human scFv antibodies isolated and described in this study represent useful reagents for rapid detection of N SARS-CoV protein and SARS virus particles in infected target cells

Isolation of KPC 3-producing Enterobacter aerogenes in a patient colonized by MDR Klebsiella pneumoniae

We describe the interspecies transmission of the plasmid-mediated blaKPC-3 gene, which confers carbapenem resistance, between clinically relevant gram-negative bacteria in a single patient. A KPC-3 producing Enterobacter aerogenes was isolated from a hospitalized patient previously colonized and then infected by a Klebsiella pneumoniae ST101 carrying the blaKPC-3 gene. The strains showed identical plasmids. Since intense horizontal exchanges among bacteria can occur in the gut, clinicians should be aware that patients colonized by carbapenem-resistant K. pneumoniae could become carriers of other carbapenem-resistant Enterobacteriaceae. © 2016 by Edimes - Edizioni Internazionali Srl. All rights reserved