ABSTRACT
Considering that recombinations produce quasispecies in lentivirus spreading, we identified and localized highly conserved sequences that may play an important role in viral ontology. Comparison of entire genomes, including 237 human, simian and non-primate mammal lentiviruses and 103 negative control viruses, led to identify 28 Conserved Lentiviral Sequences (CLSs). They were located mainly in the structural genes forming hot spots particularly in the gag and pol genes and to a lesser extent in LTRs and regulatory genes. The CLS pattern was the same throughout the different HIV-1 subtypes, except for some HIV-1-O strains. Only CLS 3 and 4 were detected in both negative control HTLV-1 oncornaviruses and D-particle-forming simian viruses, which are not immunodeficiency inducers and display a genetic stability. CLSs divided the virus genomes into domains allowing us to distinguish sequence families leading to the notion of 'species self' besides that of 'lentiviral self'. Most of acutely localized CLSs in HIV-1s (82%) corresponded to wide recombination segments being currently reported.
Subject(s)
Genome, Viral , Lentivirus/genetics , Conserved Sequence , Genes, Viral , HIV/genetics , Humans , Recombination, GeneticABSTRACT
High resistance to class IIa bacteriocins in Listeria monocytogenes has been clearly linked to lack of expression of the mptACD operon, encoding the EIIt Man mannose PTS permease. Also, intermediate resistance has been associated with membrane phospholipid modifications in the spontaneous mutants L. monocytogenes B73-V1 and B73-V2. We constructed a new mutant of L. monocytogenes that was interrupted in mpoA, and which also exhibited an intermediate resistance phenotype. The mpoABCD operon putatively encodes a PTS permease of the mannose family similar to that encoded by the mpt operon. In silico analysis indicated that mpo transcription might be dependent on sigma54. Our study demonstrated that the three intermediate resistant mutants have a slight decrease in mptACD expression, showing that the level of sensitivity is correlated to the level of mpt expression. We show a cross-regulation between mpo and mpt. In particular, the mpo mutant has a defect in mpt expression that possibly could explain its intermediate resistance phenotype.
Subject(s)
Bacteriocins/pharmacology , Drug Resistance, Bacterial/genetics , Listeria monocytogenes/drug effects , Listeria monocytogenes/genetics , Operon , Phosphoenolpyruvate Sugar Phosphotransferase System/genetics , Anti-Bacterial Agents/pharmacology , Bacterial Proteins/genetics , Bacterial Proteins/metabolism , Base Sequence , Biological Transport , DNA-Binding Proteins/genetics , DNA-Directed RNA Polymerases/genetics , Gene Deletion , Gene Expression Regulation, Bacterial , Listeria monocytogenes/metabolism , Molecular Sequence Data , Open Reading Frames , Phosphoenolpyruvate Sugar Phosphotransferase System/metabolism , Promoter Regions, Genetic , RNA Polymerase Sigma 54 , RNA, Bacterial/analysis , RNA, Messenger/analysis , Reverse Transcriptase Polymerase Chain Reaction , Sigma Factor/geneticsABSTRACT
We describe a clinical isolate of Bordetella pertussis, the agent responsible for whooping cough, composed of at least two clones harboring one or two copies of the cya locus encoding one of the major toxins, adenylate cyclase-hemolysin. No difference was observed between the two clones in murine and cellular models, probably due to the high instability of the cya locus duplication.
Subject(s)
Adenylate Cyclase Toxin/genetics , Adenylate Cyclase Toxin/toxicity , Bordetella pertussis/pathogenicity , Gene Duplication , Whooping Cough/microbiology , Animals , Bordetella pertussis/genetics , Cell Line , Disease Models, Animal , Humans , Macrophages , Mice , Trachea/microbiologyABSTRACT
Leuconostoc mesenteroides Y105 and L. mesenteroides FR52 produce both mesentericin Y105 and B105, in equal amounts. The mesentericin operons of L. mesenteroides FR52 and Y105 which are involved in mesentericin Y105 and B105 production, were both sequenced and compared. Differences were limited to the two genes, mesD and mesE, which encode the dedicated transport system of mesentericin Y105. Analysis of mesentericin non-producing mutants and complementation experiments demonstrated that the major role of the membrane fusion protein, MesE, was in bacteriocin secretion for both strains. Moreover, the secretion machinery MesDE was demonstrated to be capable of transportation and maturation of the two pre-bacteriocins, mesentericin Y105 and B105. We also demonstrate that although MesDEs from strains Y105 and FR52 have significant sequence differences, both transporters were capable of assuring secretion of either bacteriocin.
Subject(s)
ATP-Binding Cassette Transporters/genetics , ATP-Binding Cassette Transporters/metabolism , Bacteriocins/metabolism , Leuconostoc/genetics , Leuconostoc/metabolism , ATP-Binding Cassette Transporters/chemistry , Amino Acid Sequence , Bacterial Proteins/chemistry , Bacterial Proteins/genetics , Bacterial Proteins/metabolism , Bacteriocins/genetics , Base Sequence , DNA, Bacterial/chemistry , DNA, Bacterial/isolation & purification , Gene Order/genetics , Genes, Bacterial , Genetic Complementation Test , Molecular Sequence Data , Operon , Protein Transport , Sequence Analysis, DNA , Sequence HomologyABSTRACT
The sigma(54) subunit of the RNA polymerase directs the expression of specific operons in association with cognate activators. Three different activators have been detected in the Listeria monocytogenes genome on the basis of the high conservation of a specific domain. Among them, the LacR activator, of the LevR family, was found just upstream from a newly described sigma(54)-dependent operon, lpo, which presents a classical -24/-12 consensus promoter. The lpo operon encodes proteins similar to subunits of a PTS permease (EII) of the lactose family, namely LpoA (IIA) and LpoB (IIB). It also encodes a third putative protein, LpoO, with an unknown function but sharing high similarity with proteins also encoded within PTS operons from other bacteria and bearing a RGD motif. The expression of lpo was clearly dependent on LacR and sigma(54), and was induced by cellobiose, chitobiose and lactose. It underlies that the lpo operon likely encodes proteins involved in the utilization of these sugars by L. monocytogenes.
