Transposase-DNA complex structures reveal mechanisms for conjugative transposition of antibiotic resistance

Conjugative transposition drives the emergence of multidrug resistance in diverse bacterial pathogens, yet the mechanisms are poorly characterized. The Tn1549 conjugative transposon propagates resistance to the antibiotic vancomycin used for severe drug-resistant infections. Here, we present four high-resolution structures of the conserved Y-transposase of Tn1549 complexed with circular transposon DNA intermediates. The structures reveal individual transposition steps and explain how specific DNA distortion and cleavage mechanisms enable DNA strand exchange with an absolute minimum homology requirement. This appears to uniquely allow Tn916-like conjugative transposons to bypass DNA homology and insert into diverse genomic sites, expanding gene transfer. We further uncover a structural regulatory mechanism that prevents premature cleavage of the transposon DNA before a suitable target DNA is found and generate a peptide antagonist that interferes with the transposase-DNA structure to block transposition. Our results reveal mechanistic principles of conjugative transposition that could help control the spread of antibiotic resistance genes

PERCEPÇÃO DOS ENFERMEIROS SOBRE AS ATIVIDADES QUE DESENVOLVEM EM SUAS UNIDADES DE TRABALHO

The goal of this study is to verify the activities of unit nurses and ambulatory nurses in governamental hospital and to know they perceive these activities. The populación was composed by 19 nurses of both unites. The data was collect using structured interviews, and analysed in quantitative and qualitative dimensions. The results demostrated that nurses work as routine activities, based in tradicition and authority and there was no reflection about practice, causing a reiterativa practice.O presente estudo objetiva o conhecimento das atividades realizadas pelas enfermeiras de unidades de internação e ambulatório de um hospital de ensino e conhecer como percebem o desenvolvimento dessas atividades. Como população do estudo, foram consideradas 19 enfermeiras lotadas em diferentes unidades do hospital. Para a obtenção dos dados foi adotada a técnica de entrevista estruturada. As informações obtidas foram analisadas nos seus aspectos quantitativos e qualitativos. Constatou-se que as enfermeiras desenvolvem suas atividades profissionais de forma rotineira, embasadas na tradição e na autoridade e não na reflexão sobre a prática