A new antimicrobial target in Staphylococcus aureus – amidation of peptidoglycan

• Autor(a) principal: Gonçalves, Bárbara Vitorino
• Data de Publicação: 2014
• Tipo de documento: Dissertação
• Idioma: eng
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: http://hdl.handle.net/10362/14132
• topic: MurT-GatD complex; Peptidoglycan amidation; Staphylococcus aureus; Resistance to β-lactams; Structure determination by NMR

taphylococcus aureusis adangerousopportunistic pathogenwith a large number of virulence factors, responsible for a wide range of diseases. Its clinical importance is mainly due to itshigh capacity to accumulate resistance mechanismsto virtually all antibiotics. Over the last century,hugeeffortshavebeen dedicatedto the study of the molecular mechanisms underlying resistance of S. aureusto β-lactam antibiotics. Besides the exogenousmecAgene, identified as the main player of the mechanism of β-lactam resistance, several housekeeping geneswerealso identified to be requiredfor theoptimal expressionof resistance, the so-calledauxiliary genes. The use of combination agents in synergy with β-lactams has already proven to be efficient in restoring β-lactam activityagainst resistantstrains.Among the auxiliary genes, murT-gatDoperonwas recently identified as encoding for the enzymes responsible for amidation of the glutamate residue of peptidoglycan. Glutamate amidation, a secondary modification of peptidoglycan,is essential for S. aureusviability and is involved in the mechanisms of resistance to β-lactams and to lysozyme, being an excellent target for the development of new antimicrobial compounds.The purpose of this Master thesiswasto dynamically characterize the structure of MurT-GatD complex by Nuclear Magnetic Resonance (NMR). Structural information on the physical interaction between the two partner proteins will be an essential contribution for the future developmentofa compound that blocks MurT-GatD association. Such a compound would act in synergywith β-lactams, restoring S. aureus susceptibility. The results of this study identified the DUF1727 domain (C-terminal domain of MurT protein) as responsible for the interaction between MurT and GatD and also showed, through 1H-15N-spectrum NMR analysis,a strong interaction between DUF1727 and GatD protein.This work paved the way for the comprehensive analysis of MurT-GatD interaction.