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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

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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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New Panfungal Real-Time PCR Assay for Diagnosis of Invasive Fungal Infections.

4. Valero C, de la Cruz-Villar L, Zaragoza O, Buitrago MJ. New Panfungal Real-Time PCR Assay for Diagnosis of Invasive Fungal Infections. J Clin Microbiol. 2016 Dec;54(12):2910-2918. doi: 10.1128/JCM.01580-16. Epub 2016 Sep 14. PMID: 27629898.

DOI

A Multiplex Real-Time PCR Assay for Identification of Pneumocystis jirovecii, Histoplasma capsulatum, and Cryptococcus neoformans/Cryptococcus gattii in Samples from AIDS Patients with Opportunistic Pneumonia

6. Gago S, Esteban C, Valero C, Zaragoza O, Puig de la Bellacasa J, Buitrago MJ. A multiplex real-time PCR assay for identification of Pneumocystis jirovecii, Histoplasma capsulatum, and Cryptococcus neoformans/Cryptococcus gattii in samples from AIDS patients with opportunistic pneumonia. J Clin Microbiol. 2014 Apr;52(4):1168-76. doi: 10.1128/JCM.02895-13. Epub 2014 Jan 29. PMID: 24478409.

PUBMED DOI

Analysis of strain relatedness using High Resolution Melting in a case of recurrent candiduria

7. Gago S, Lorenzo B, Gomez-Lopez A, Cuesta I, Cuenca-Estrella M, Buitrago MJ. Analysis of strain relatedness using high resolution melting in a case of recurrent candiduria. BMC Microbiol. 2013 Jan 23;13:13. doi: 10.1186/1471-2180-13-13. PMID: 23343107.

PUBMED DOI

High-Resolution Melting Analysis for Identification of the Cryptococcus neoformans-Cryptococcus gattii Complex

8. Gago S, Zaragoza Ó, Cuesta I, Rodríguez-Tudela JL, Cuenca-Estrella M, Buitrago MJ. High-resolution melting analysis for identification of the Cryptococcus neoformans-Cryptococcus gattii complex. J Clin Microbiol. 2011 Oct;49(10):3663-6. doi: 10.1128/JCM.01091-11. Epub 2011 Aug 10. PMID: 21832024.

PUBMED DOI

Performance of Panfungal- and Specific-PCR-Based Procedures for Etiological Diagnosis of Invasive Fungal Diseases on Tissue Biopsy Specimens with Proven Infection: a 7-Year Retrospective Analysis from a Reference Laboratory

9. Buitrago MJ, Bernal-Martinez L, Castelli MV, Rodriguez-Tudela JL, Cuenca-Estrella M Performance of panfungal--and specific-PCR-based procedures for etiological diagnosis of invasive fungal diseases on tissue biopsy specimens with proven infection: a 7-year retrospective analysis from a reference laboratory. J Clin Microbiol. 2014 May;52(5):1737-40. doi: 10.1128/JCM.00328-14. Epub 2014 Feb 26.PMID: 24574295.

PUBMED DOI

Epidemiología actual y diagnóstico de laboratorio de las micosis endémicas en España

11. Buitrago MJ, Cuenca-Estrella M. [Current epidemiology and laboratory diagnosis of endemic mycoses in Spain]. Enferm Infecc Microbiol Clin. 2012 Aug;30(7):407-13. doi: 10.1016/j.eimc.2011.09.014. Epub 2011 Nov 29. PMID: 22130575 Review. Spanish.

PUBMED DOI

A matrix-assisted laser desorption/ionization time of flight mass spectrometry reference database for the identification of Histoplasma capsulatum

12. Buitrago MJ, Bernal-Martínez L, Castelli MV, Rodríguez-Tudela JL, Cuenca-Estrella M. Histoplasmosis and paracoccidioidomycosis in a non-endemic area: a review of cases and diagnosis. J Travel Med. 2011 Jan-Feb;18(1):26-33. doi: 10.1111/j.1708-8305.2010.00477.x. Epub 2010 Nov 28. PMID: 21199139.

PUBMED DOI

Copy Number Variation of Mitochondrial DNA Genes in Pneumocystis jirovecii According to the Fungal Load in BAL Specimens

13. Valero C, Buitrago MJ, Gago S, Quiles-Melero I, García-Rodríguez J. A matrix-assisted laser desorption/ionization time of flight mass spectrometry reference database for the identification of Histoplasma capsulatum. Med Mycol. 2018 Apr 1;56 (3):307-314. doi: 10.1093/mmy/myx047. PMID: 28992262.

PUBMED DOI

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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