Pathogenic bacteria are increasingly resistant to antibiotics. This may lead to a post-antibiotic scenario in which some studies predict, in the mid-term, a higher mortality for this cause than, for instance, cancer diseases. This has fostered our research to focus on the search of novel antimicrobials that circumvent antimicrobial resistance issues.
Among the few alternatives that are glimpsed to treat this problem are endolysins encoded by phages, modular enzymes that hydrolyze specific bonds of bacterial peptidoglycan. New phage endolysins are being tested or by construction of chimeras fusing different functional domains. These enzymes are effective in both planktonic cultures and in biofilms. Specifically, during 2017, the molecular basis of the recognition of the cell wall by endolysin Cpl-7 (encoded by a pneumococcal phage) was studied. In addition, a new chimeric enzyme (Csl2) has been constructed which has shown its bactericidal activity in infections caused by Streptococcus suis, an emerging zoonotic agent. Validation of in vitro results is done in mouse or zebrafish models.
Most chronic infections are caused by bacteria that grow into biofilms. The antibiotic tolerance of these communities is well known. Frequently, the human nasopharynx is colonized by encapsulated pneumococci associated with non-encapsulated pneumococci and non-typeable H. influenzae (NTHi) strains. During 2017 the requirements for the formation of mixed in vitro biofilms between S. pneumoniae and NTHi strains were studied. This model has been used to demonstrate the antibiofilm activity of two antioxidants frequently used in clinical practice: N-acetyl-L-cysteine and cysteamine. Moreover, a novel procedure allowing the specific recognition of S. pneumoniae in mixed cultures has been developed. This method involves the use of the HPA lectin from Helix pomatia.
Pneumococcal surface proteins play an essential role in bacterial viability and virulence, and yet, they have not been considered so far as targets for the development of new antibiotics. We have found a panoply of molecules, from low molecular weight compounds to peptides and proteins, that interfere with the role of these proteins. Moreover, we are employing the concept of chemical multivalency to design and assay nanoparticles containing several copies of the cited active compounds, leading to an exponential increase in antimicrobial activity.
Key words: Streptococcus pneumoniae, virulence, immunity, complement system, carrier state, choline-binding proteins, biofilms, enzybiotics, bacteriophages, structure-function, nanobiotechnology
Roig-Molina E, Domenech M, Retamosa M de G, Nácher-Vázquez M, Rivas L, Maestro B, García
P, Garcia E, Sanz JM
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Bello-Gil D, Maestro B, Fonseca J, Dinjaski N, Prieto MA, Sanz JM . Poly-3- hydroxybutyrate functionalization with BioF-tagged recombinant proteins. Appl. Environ. Microbiol.84: e02595-17
Vázquez R, García E, García P . Phage lysins for fighting bacterial respiratory infections: a new generation of antimicrobials. Front. Immunol. https://doi.org/10.3389/fimmu.2018.02252.
Ferrándiz MJ, Cercenado MI, Domenech M, Tirado-Vélez JM, Escolano-Martínez MS, Yuste J, García E, de la Campa AG, Martín-Galiano AJ . An uncharacterized member of the Gls24 protein superfamily is a putative sensor of essential amino acid availability in Streptococcus pneumoniae. Microb Ecol. https://doi.org/10.1007/s00248-018-1218-9
Herta T, Bhattacharyya A, Bollensdorf C, Kabus C, García P, Suttorp N, Hippenstiel S, Zahlten J . DNA-release by Streptococcus pneumoniae autolysin LytA induced Krueppel-like factor 4 expression in macrophages. Sci Rep 8:5723
Bello-Gil D, Roig-Molina E, Fonseca J, Sarmiento-Fernández MD, Ferrándiz M, Franco E, Mira E,
Maestro B, Sanz JM
. An enzymatic system for decolorisation of wastewater dyes using immobilized CueO laccase-like multicopper oxidase on poly-3-hydroxybutyrate. Microb. Biotech. 11: 881 - 892
Chan WT, Domenech M, Moreno-Córdoba I, Navarro-Martínez V, Nieto C, Moscoso M, García E, Espinosa M . The Streptococcus pneumoniae yefM-yoeB and relBE toxin-antitoxin operons participate in oxidative stress and biofilm formation. Toxins (Basel) 10: 378
Zamora-Carreras H, Maestro B, Strandberg E, Ulrich A, Sanz JM*, Jiménez MA* . Roles of amphipathicity and hydrophobicity in the micelle-driven structural switch of a 14-mer peptide core from a choline-binding repeat. Chem. Eur. J. 24: 5825 - 5839
Càmara J, Cubero M, Martín-Galiano AJ, García E, Grau I, Nielsen JB, Worning P, Tubau F, Pallarés R, Domínguez MA, Kilian MA, Liñares J, Westh H, Ardanuy C . Evolution of the -lactam resistant Streptococcus pneumoniae PMEN3 clone over a 30-year period in Barcelona, Spain. J. Antimicrob. Chemother. https://doi.org/10.1093/jac/dky305
Corsini B, Díez-Martínez R, Aguinagalde L, González-Camacho F, García-Fernández E, Letrado P, García P, Yuste J . Chemotherapy with phage lysins reduces pneumococcal colonization of the respiratory tract. Antimicrob Agents Chemother 62:e02212-17
Letrado P, Corsini B, Díez-Martínez R, Bustamante N, Yuste JE, García P . Bactericidal synergism between antibiotics and phage endolysin Cpl-711 to kill multidrug-resistant pneumococcus. Future Microbiol 13:1215-23
— MCyT, BMC2000-1002 (2000-2003).
— Fundación Ramón Areces (2000-2003).
— BIO2000-0009-P4-04 (2001-2005).
— MCyT, BMC2003-00074 (2003-2006).
— Ministerio de Sanidad y Consumo, Redes G03/103 y C03/104.
— MCyT, SAF2006-00390 (2006-2009)
— Member of the CIBER of Respiratory Diseases (Instituto de Salud Carlos III)
– CAM, COMBACT Program, S-BIO-0260/2006 (2007-2010)
– MICINN, SAF2009-10824 (2010-2012)
– MICINN, IPT-2011-1337-010000
- MINECO, SAF2012-39444-C02-01 (2013-2015)
- MINECO: BFU2010-17824 (2011-2014)
- BIO2013-47684-R (2014-2016)
- BIO2016-79323-R (2017-2019)
- EU (FP7): HEALTH-F3-2009-223111
- MINECO, SAF2017-88664-R (2018-2020)
International DropSens Award to the best research work in Applied Electroanalytical Chemistry. Malmö (Sweden). June 2014.