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Bacterial Genetics

Líneas de investigación

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Bacterial Genetics

Our group has been studying for more than 30 years the mechanisms of antibiotic resistance in Streptococcus pneumoniae (Spn). Our objectives are to understand the molecular basis of antimicrobial action, to search for new targets of action and new compounds. Seconeolitsine (SCN) is one of these new compounds targeting topoisomerase I (Topo I). As for the search for new targets, our research has focused in recent years on the factors that organize the topology of the chromosome, allowing optimal compaction (about 1000-fold) to harmonize its replication, chromosome segregation and gene expression. This compaction is mediated both by the level of DNA supercoiling (Sc) and by association with nucleoid-binding proteins (NAPs). The level of Sc depends mainly on the enzymatic activities of their DNA topoisomerases, reaching a homeostatic equilibrium by the opposite activities of the topoisomerases that relax DNA (Topo I and Topo IV), and of gyrase, which introduces negative Sc. Our group has characterized the three Spn topoisomerases and two NAPs: HU and SatR. In addition, the availability of antimicrobials that inhibit each of the Spn topoisomerases has allowed us to analyze their transcriptome under conditions of local or global change of the Sc level and to define gene domains of coordinated transcription and similar functions. Fluoroquinolones, which inhibit Topo IV and gyrase, produce local changes in Sc that induce alterations in 6% of the transcriptome, altering metabolic pathways that originate an increase in reactive oxygen species (ROS) that contribute to lethality, in accordance with the general mechanism of bactericidal antibiotics. On the other hand, the induction of global changes in Sc by novobiocin (NOV, gyrase inhibitor), or by SCN (Topo I inhibitor), has allowed us to define topological domains. Global changes in Sc include the regulation of topoisomerase genes: its decrease activates the transcription of gyrase genes (gyrA, gyrB) and inhibits those of Topo IV (parEC) and Topo I (topA); the increase in Sc regulates the expression of topA. Decreased Sc affects 37% of the genome, with >68% of genes clustered in 15 domains. Increased Sc affects 10% of the genome, with 25% of the genes clustered in 12 domains. The AT content in the genome correlates with the domains, being higher in UP domains than in DOWN domains. The genes in the different domains have common functional characteristics, indicating that they have been subjected to topological selective pressure to determine the location of genes involved in metabolism, virulence and competition. 

The current objectives of the group are:
1.    Identification of factors that stabilize chromosome topology: NAPs, ncRNAs, intra-chromosomal interactions.
2.    Regulation of transcription in response to topological stress: in vivo localization of DNA topoisomerases, RNA polymerase and NAPs.
3.    Topo I as a new antimicrobial target and action of SCN. 
4.    Design of antisense RNAs and use of the CRISPR system as new antibacterial agents.

Proyectos de investigación

Content with Investigacion Genética Bacteriana .

1) Project Title: Interaction Between DNA Supercoiling and Transcription in the Human Pathogen  Streptococcus pneumoniae

Principal Investigator:   Adela González de la Campa  
Funding Entity:   Ministry of Science and Innovation, State Research Agency (Call for "R&D&I Projects" 2020 – "Research Challenges" and "Knowledge Generation" Modalities).  
Reference:   PID2021-124738OB-100.  
Duration:   2022-2025.  
Funding Amount:   €108,900.
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2) Project Title:   Study of the Factors Organizing the Chromosome of  Streptococcus pneumoniae: New Antibiotic Targets and Resistance Mechanisms.

Principal Investigator:   Adela González de la Campa  
Funding Entity:   Ministry of Economy, Industry, and Competitiveness. State Research Agency.  
Reference:   BIO2017-82951-R.  
Duration:   2018-2020.  
Funding Amount:   €169,400.  

3) Project Title:   Role of DNA Topoisomerases and Nucleoid-Associated Proteins in the Chromosome Organization of  Streptococcus pneumoniae: Response to Antibiotics and Virulence.  

Principal Investigator:   Adela González de la Campa  
Funding Entity:   Ministry of Economy and Competitiveness. Secretariat of State for Research, Development, and Innovation.  
Reference:   BIO2014-55462.  
Duration:   2015-2017.  
Funding Amount:   €193,600.  

4) Project Title:   The Control of Supercoiling Level in  Streptococcus pneumoniae  as an Antimicrobial Target.  

Principal Investigator:   Adela González de la Campa  
Funding Entity:   Ministry of Economy and Competitiveness. Secretariat of State for Research, Development, and Innovation.  
Reference:   BIO2011-25343.  
Duration:   2012-2015.  
Funding Amount:   €209,000.  

5) Project Title:   Role of Small Non-Coding RNAs in the Pathogenicity of  Streptococcus pneumoniae.   

Principal Investigator:   Mónica Amblar Esteban  
Funding Entity:   Ministry of Economy and Competitiveness. Strategic Health Action (AES).  
Reference:   PI11/00656.  
Duration:   2012-2015.  
Funding Amount:   €198,714.
 

Publicaciones destacadas

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Viruses from a cluster of HIV-1 Elite controllers inherit viral characteristics associated with the clinical non-progressor phenotype.

Casado C, Marrero-Hernández S, Márquez-Arce D, Pernas M, Marfil S, Borràs-Grañana F, Olivares I, Cabrera-Rodríguez R, Valera M-S, de Armas-Rillo L, Lemey P, Blanco J, Valenzuela-Fernández A, Lopez-Galíndez C. 2018. Viral characteristics associated with the clinical nonprogressor phenotype are inherited by viruses from a cluster of HIV-1 elite controllers. mBio 9:e02338-17.

PUBMED DOI

Factors Leading to the Loss of Natural Elite Control of HIV-1 Infection.

María Pernas, Laura Tarancón-Diez, Esther Rodríguez-Gallego, Josep Gómez, Julia G. Prado, Concepción Casado, Beatriz Dominguez-Molina, Isabel Olivares, Maite Coiras, Agathe León, Carmen Rodriguez, Jose Miguel Benito, Norma Rallón, Montserrat Plana, Onofre Martinez-Madrid, Marta Dapena, Jose Antonio Iribarren, Jorge del Romero, Felipe García, José Alcamí, Mª Ángeles Muñoz-Fernández, Francisco Vidal, Manuel Leal, Cecilio Lopez-Galindeza, Ezequiel Ruiz-Mateos. On behalf of ECRIS integrated in the Spanish AIDS Research Network. (2018). Factors Leading to the Loss of Natural Elite Control of HIV-1 Infection. J.Virol. 92, 5 e01805-17.

PUBMED DOI

Human Immunodeficiency Virus Type 1 2-LTR circles: a subject for debate

Isabel Olivares, María Pernas, Concepción Casado and Cecilio López-Galíndez. Human Immunodeficiency Virus Type 1 2-LTR circles: a subject for debate. (2016). AIDS review, 18: 23-31.

PUBMED DOI

Improved antibody cross-neutralizing activity in HIV-1 dual double infected LTNP patients.

María Pernas, Concepción Casado, Victor Sanchez-Merino, Alberto Merino-Mansilla, Isabel Olivares, Eloisa Yuste, Cecilio Lopez-Galindez. Improved antibody cross-neutralizing activity in HIV-1 dual double infected LTNP patients. (2015) PLoS One. Aug 10; 10 (8):e0134054. doi: 10.1371/journal.pone.0134054. eCollection.

PUBMED DOI

Influence of Mutation and Recombination on HIV-1 in vitro Fitness Recovery.

Ramón Lorenzo-Redondo, Miguel Arenas, and Cecilio Lopez-Galindez. Influence of Mutation and Recombination on HIV-1 in vitro Fitness Recovery. (2015) Mol Phylogenet Evol. Sep 7. pii: S1055-7903(15)00259-6. doi: 10.1016/j.ympev.2015.09.001. PMID: 26358613

PUBMED DOI

Analysis of HIV-1 “in vitro” evolution through 3D real fitness landscapes constructed by Self Organizing Maps.

Ramón Lorenzo‐Redondo, Soledad Delgado, Federico Morán, and Cecilio Lopez‐Galindez. Analysis of HIV-1 “in vitro” evolution through 3D real fitness landscapes constructed by Self Organizing Maps. (2014) PLoS One. 9(2): e88579.

PUBMED DOI

Identification of a Spanish HIV-1 Long Term Non-Progressor cluster infected with a low replicating virus.

Concepción Casado, Maria Pernas, Virginia Sandonis, Tamara Alvaro-Cifuentes, Isabel Olivares, Rosa Fuentes, Lorena Martínez Prats, Eulalia Grau, Lidia Ruiz, Rafael Delgado, Carmen Rodríguez, Jorge del Romero, and Cecilio López-Galíndez. Identification of a Spanish HIV-1 Long Term Non-Progressor cluster infected with a low replicating virus. (2013). PLoS One. 8 (10):e77663.

PUBMED DOI

A Genome-to-Genome Analysis of Associations between Human Genetic Variation, HIV-1 Sequence Diversity, and Retroviral Control.

Istvan Bartha Jonathan M Carlson, Chanson J Brumme, Paul J McLaren, Zabrina L Brumme, Mina John, David W Haas, Javier Martinez-Picado, Cecilio López Galíndez, Andri Rauch, Huldrych F Günthard, Enos Bernasconi, Pietro Vernazza, Thomas Klimkait, Sabine Yerly, Jennifer Listgarten, Nico Pfeifer, Zoltan Kutalik, Todd M Allen, Viktor Müller, P Richard Harrigan, David Heckerman, Amalio Telenti, and Jacques Fellay, for the HIV Genome-to-Genome Study and the Swiss HIV Cohort Study. A Genome-to-Genome Analysis of Associations between Human Genetic Variation, HIV-1 Sequence Diversity, and Retroviral Control. (2013). Elife. 2013;2:e01123.

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Content with Investigacion Genética Bacteriana .

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Información adicional

Streptococcus pneumoniae is a human pathogen that, despite the development of vaccines, continues to be an important cause of mortality and morbidity. We investigate the mechanisms of antibiotic resistance in this bacterium. On the one hand by identifying new therapeutic targets and on the other hand by investigating the molecular basis of the action of antibiotics already used in clinical practice (the fluoroquinolones levofloxacin and moxifloxacin) or not yet used (seconeolitsine). For this purpose, we used a multidisciplinary analysis involving genomics, transcriptomics and proteomics to understand the organization of the S. pneumoniae chromosome and the identification of the factors that stabilize this organization, including ncRNAs. Changes in the level of global supercoiling, either by inhibition of gyrase (decrease) or by inhibition of topoisomerase I (increase) alter the transcriptome. The modulated genes are located in domains, whose genes show specific functional characteristics. The aim is to identify new factors essential for S. pneumoniae physiology and to characterize transcriptional regulation in response to topological stress. In addition, RNA interference technology and CRISPR systems will be used as novel antibacterials. These studies will establish the bases for translational research aimed at the development of new therapeutic targets for the treatment of pneumococcal diseases.

Streptococcus pneumoniae is a human pathogen that, despite the development of vaccines, continues to be an important cause of mortality and morbidity. We investigate the mechanisms of antibiotic resistance in this bacterium. On the one hand by identifying new therapeutic targets and on the other hand by investigating the molecular basis of the action of antibiotics already used in clinical practice (the fluoroquinolones levofloxacin and moxifloxacin) or not yet used (seconeolitsine). For this purpose, we used a multidisciplinary analysis involving genomics, transcriptomics and proteomics to understand the organization of the S. pneumoniae chromosome and the identification of the factors that stabilize this organization, including ncRNAs. Changes in the level of global supercoiling, either by inhibition of gyrase (decrease) or by inhibition of topoisomerase I (increase) alter the transcriptome. The modulated genes are located in domains, whose genes show specific functional characteristics. The aim is to identify new factors essential for S. pneumoniae physiology and to characterize transcriptional regulation in response to topological stress. In addition, RNA interference technology and CRISPR systems will be used as novel antibacterials. These studies will establish the bases for translational research aimed at the development of new therapeutic targets for the treatment of pneumococcal diseases.

Content with Investigacion Genética Bacteriana .

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