New antibiotics are urgently needed to treat the increasing number of life-threatening bacterial infections that are resistant to current therapies due to the widespread problem of bacterial resistance towards existing drugs. The paucity of effective drugs for the treatment of bacterial infections prompted the scientific community to think about novel strategies for discovering new classes of antibacterial agents, since, actually, most of the new drugs are merely variant of older overused antibiotics. Among the new putative targets, bacterial cell division is one essential process that is not yet targeted by clinically approved antibacterials and, moreover, most of the divisome components are characterized by essentiality and prokaryotic specificity. Bacterial cytokinesis is orchestrated by the divisome, a complex of proteins that co-ordinates and regulates the invagination of the cytoplasmic membrane, inward growth of the peptidoglycan layer and the outer membrane. To initiate cell division, the GTP-binding tubulin-like FtsZ protein forms an intracellular ring at the division site localized equidistant between the two cell poles, by FtsZ monomer self-assembly. The predominantly cytoplasmic proteins FtsA, ZipA and ZapA, which are the first to be recruited to the Z ring to form a complex with FtsZ. These proteins are responsible for tethering FtsZ to the membrane and stabilising the Z ring. These early recruits are followed by a group of single- or multipass membrane proteins that include bitopic (FtsQ, FtsL, FtsB, FtsN, FtsI) and polytopic (FtsK, FtsW) membrane proteins. In these last 10 years, various natural or synthetic inhibitors against FtsZ protein or the FtsZ-ZipA complex or FtsA were identified. Although it is not known whether or not these compounds could have a medical application, these data confirm the hypothesis that these proteins represent an excellent antibacterial target. Other divisome components would be taken into account as potential targets for new antibiotics, and, amongst these, FtsQ, a highly conserved component of the divisome, that forms a complex with two other cell division proteins, FtsB and FtsL, necessary for linking the upstream division proteins, predominantly cytoplasmic, with the downstream predominantly periplasmic division proteins. The FtsQ location, external to the cytoplasm, allows to the inhibitors a more easily accession to this protein than intracellular proteins and removes the problematic issue of resistance development due to drug-efflux pumps. Furthermore, unlike FtsZ and FtsA, there are no identified human homologues to this protein, thereby increasing its potential as antibacterial target drugs. FtsQ is able to interact with various division proteins. Its domains involved in these interactions were identified by two-hybrid assays, co-immunoprecipitation experiments, and progressive deletions of the ftsQ gene. In addition, the selection and the study of FtsQ interaction-defective mutants constituted the basis for identify the FtsQ residues involved in the interaction with the other partner proteins and to investigate the biological significance of these interactions. The obtained results highlight that mutations in the POTRA domain strongly affect the functionality of FtsQ, assigning to this domain a prevalent role in the biological effects of this protein. In order to evaluate the possibility to identify FtsQ, and, in particular its POTRA domain, as a potential target for new antibacterial drugs, we performed competition experiments where a protein fragment containing the POTRA region, was used as inhibitor of the bacterial growth. Although preliminary, our results suggest that new antibacterial agents inhibiting the POTRA domain would be explored. In particular, synthetic oligopeptides designed on the POTRA region would be used as antibacterial drugs. Moreover, since two separates sites for both FtsQ homodimerization and FtsI and FtsN interactions were identified, in order to maximize the inhibitory effect a cocktail of oligopetides derived from these two regions could be used to disrupt the bacterial division machinery. Keywords divisome, protein-protein interaction, interaction-defective mutants
The FtsQ division proteins interactions as potential targets for new antibacterial drugs (2010) International Conference on antimicrobial research
P Ghelardini
2010
Abstract
New antibiotics are urgently needed to treat the increasing number of life-threatening bacterial infections that are resistant to current therapies due to the widespread problem of bacterial resistance towards existing drugs. The paucity of effective drugs for the treatment of bacterial infections prompted the scientific community to think about novel strategies for discovering new classes of antibacterial agents, since, actually, most of the new drugs are merely variant of older overused antibiotics. Among the new putative targets, bacterial cell division is one essential process that is not yet targeted by clinically approved antibacterials and, moreover, most of the divisome components are characterized by essentiality and prokaryotic specificity. Bacterial cytokinesis is orchestrated by the divisome, a complex of proteins that co-ordinates and regulates the invagination of the cytoplasmic membrane, inward growth of the peptidoglycan layer and the outer membrane. To initiate cell division, the GTP-binding tubulin-like FtsZ protein forms an intracellular ring at the division site localized equidistant between the two cell poles, by FtsZ monomer self-assembly. The predominantly cytoplasmic proteins FtsA, ZipA and ZapA, which are the first to be recruited to the Z ring to form a complex with FtsZ. These proteins are responsible for tethering FtsZ to the membrane and stabilising the Z ring. These early recruits are followed by a group of single- or multipass membrane proteins that include bitopic (FtsQ, FtsL, FtsB, FtsN, FtsI) and polytopic (FtsK, FtsW) membrane proteins. In these last 10 years, various natural or synthetic inhibitors against FtsZ protein or the FtsZ-ZipA complex or FtsA were identified. Although it is not known whether or not these compounds could have a medical application, these data confirm the hypothesis that these proteins represent an excellent antibacterial target. Other divisome components would be taken into account as potential targets for new antibiotics, and, amongst these, FtsQ, a highly conserved component of the divisome, that forms a complex with two other cell division proteins, FtsB and FtsL, necessary for linking the upstream division proteins, predominantly cytoplasmic, with the downstream predominantly periplasmic division proteins. The FtsQ location, external to the cytoplasm, allows to the inhibitors a more easily accession to this protein than intracellular proteins and removes the problematic issue of resistance development due to drug-efflux pumps. Furthermore, unlike FtsZ and FtsA, there are no identified human homologues to this protein, thereby increasing its potential as antibacterial target drugs. FtsQ is able to interact with various division proteins. Its domains involved in these interactions were identified by two-hybrid assays, co-immunoprecipitation experiments, and progressive deletions of the ftsQ gene. In addition, the selection and the study of FtsQ interaction-defective mutants constituted the basis for identify the FtsQ residues involved in the interaction with the other partner proteins and to investigate the biological significance of these interactions. The obtained results highlight that mutations in the POTRA domain strongly affect the functionality of FtsQ, assigning to this domain a prevalent role in the biological effects of this protein. In order to evaluate the possibility to identify FtsQ, and, in particular its POTRA domain, as a potential target for new antibacterial drugs, we performed competition experiments where a protein fragment containing the POTRA region, was used as inhibitor of the bacterial growth. Although preliminary, our results suggest that new antibacterial agents inhibiting the POTRA domain would be explored. In particular, synthetic oligopeptides designed on the POTRA region would be used as antibacterial drugs. Moreover, since two separates sites for both FtsQ homodimerization and FtsI and FtsN interactions were identified, in order to maximize the inhibitory effect a cocktail of oligopetides derived from these two regions could be used to disrupt the bacterial division machinery. Keywords divisome, protein-protein interaction, interaction-defective mutantsI documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
