INVESTIGADORES
ALBARRACIN Virginia Helena
congresos y reuniones científicas
Título:
Screening for Photolyases and LOV-domains in UV-resistant extremophile bacteria isolated from High-Altitude Andean Lakes in Argentina
Autor/es:
ALBARRACÍN V.H.; PATHAK G.; FARIAS M.E.; BORSARELLI C.D.; GÄRTNER W.
Lugar:
Düsseldorf
Reunión:
Congreso; 15th INTERNATIONAL CONGRESS IN PHOTOBIOLOGY; 2009
Resumen:
High-Altitude Andean Lakes (HAAL; between 3,000 and 6,000 masl) at the northwest of Argentina in the Puna and Andean regions, are considered extreme environments of biotechnological interest. These HAAL experience a wide daily range in temperatures (from -20 ° to 30 ºC), are slight saline to hypersaline, subject to low phosphate availability and high intensity of solar UV-B radiation. Microbial communities living in such aquatic ecosystems are tolerant to large fluctuations in environmental factors in addition to steady-state extreme conditions (1-3). A collection of 200 extremophile strains from these unique environments harbours representatives of Eubacteria, Firmicutes and Actinobacteria, Proteobacteria (gamma, alpha and beta) and Archaea (1-4). Amongst the microorganisms isolated and characterized, a widespread UV-B resistance profile was determined (2-4). Particularly, some isolates were able to survive during 36 h to a high UV-B irradiation (53.3 kJ m-2) while they displayed low Cyclobutane-Pyrimidine-Dimer accumulation, which suggests a very efficient repair of DNA photo-damage by photo-dependent mechanisms. The enzymes implied in the direct photo-reparation of DNA damage, such us photolyases, are of particular interest, because, so far, no records of these enzymes has been reported in such extremophilic bacteria. Another important aspect of this study is a screen for the presence and the physiological role of proteins containing LOV (Light-Oxygen-Voltage) domains, which have been implicated in cellular signalling processes and are reported to be present across diverse forms of life (5). Since the extremophilic bacteria found in the HAAL are highly conditioned by light irradiance, it could be the case that LOV-domains play a role in regulating tolerance activities, such as, the photo-repairing abilities. Taking account of these facts, the aim of this work is to screen for photolyases and LOV-domains genes in selected UV-resistant bacteria from HAAL. The following strains previously isolated from HAAL(1-4) were used in this study: Nocardia sp. A5, Brevibacterium sp. Ap13, Stenotrophomonas spp. N24 and N38, Acinetobacter spp. N40, Ver3, Ver5 and Ver7 and Pseudomonas sp. V1; all of which showed resistance to UV-light. Among them, A5, V1 and Ver3 were the most UV-B resistant strains; 100 % of survival was obtained after an irradiation of 24 kJ m-2, while a decrease of one order of magnitude was observed after an UV-B irradiation of 48 kJ m-2. In a preliminary screening, the genus-specific subsets of PCR primers showed a presence of photolyase genes in Acinetobacter sp. Ver3 and Ver7 and Pseudomonas sp. V1. Similarly, application of a LOV-domain specific DNA microarray (5) indicated the presence of LOV domain in three isolates. In view of these results, we propose the UV-B resistant strains Nocardia sp. A5, Acinetobacter sp. Ver3, and Pseudomonas sp. V1 as interesting model strains to study photorepairing mechanisms. These studies could originate new perspectives to the knowledge of light-inducible flavoproteins in relation or co-regulation with LOV domains. 1- Dib, J.R., Weiss, A., Neumann, A., Ordoñez, O., Estévez, M.C., Farías, M.E. (2009) Isolation of bacteria from remote high altitude Andean wetlands able to grow in the presence of antibiotics. Recent Patents Anti-Infect Drug Disc. 4: 66-76. 2- Dib, J., Motok, J., Fernández Zenoff, V., Ordoñez, O. and Farías, M. E. (2008a). Occurrence of resistance to antibiotics, UV-B and arsenic in bacteria isolated from extreme environments in high altitude (above 4400 m) Andean wetlands. Curr Microbiol 56: 510–517. 3- Fernández Zenoff, V., Sineriz, F. and Farias, M. E. (2006) Diverse responses to UV-B radiation and repair mechanisms of bacteria isolated from high-altitude aquatic environments. Appl Environ Microbiol 72: 7857–7863. 4- Zenoff, V., Heredia, J. Ferrero, M., Sineriz, F. and Farias, M. E. (2006) Diverse UV-B resistance of culturable bacterial community from high-altitude wetland water. Curr. Microbiol. 52: 359–362. 5- Pathak, G.P., Ehrenreich, A., Losi, A., Streit, W.R., and Gärtner, W. (2009) Novel Blue Light-Sensitive Proteins from a Metagenomic Approach. Env. Microbiol. (submitted).