Extremophilic Acinetobacter Strains from High-Altitude Lakes in Argentinean Puna: Remarkable UV-B Resistance and Efficient DNA Damage Repair
- 527 Downloads
High-Altitude Andean Lakes (HAAL) of the South American Andes are almost unexplored ecosystems of shallow lakes. The HAAL are recognized by a remarkably high UV exposure, strong changes in temperature and salinity, and a high content of toxic elements, especially arsenic. Being exposed to remarkably extreme conditions, they have been classified as model systems for the study of life on other planets. Particularly, Acinetobacter strains isolated from the HAAL were studied for their survival competence under strong UV-B irradiation. Clinical isolates, Acinetobacter baumannii and Acinetobacter johnsonii, served as reference material. Whereas the reference strains rapidly lost viability under UV-B irradiation, most HAAL-derived strains readily survived this exposure and showed less change in cell number after the treatment. Controls for DNA repair activity, comparing dark repair (DR) or photo repair (PR), gave evidence for the involvement of photolyases in the DNA repair. Comparative measurements by HPLC-mass spectrometry detected the number of photoproducts: bipyrimidine dimers under both PR and DR treatments were more efficiently repaired in the HAAL strains (up to 85 % PR and 38 % DR) than in the controls (31 % PR and zero DR ability). Analysis of cosmid-cloned total genomic DNA from the most effective DNA-photorepair strain (Ver3) yielded a gene (HQ443199) encoding a protein with clear photolyase signatures belonging to class I CPD-photolyases. Despite the relatively low sequence similarity of 41 % between the enzymes from Ver3 and from E. coli (PDB 1DNPA), a model-building approach revealed a high structural homology to the CPD-photolyase of E. coli.
KeywordsAcinetobacter Extremophiles High-Altitude Andean Lakes Photolyase UV-resistance
The authors acknowledge the generous financial support by the PICT-MPI 2006 01090 Project (FONCyT, Argentina) the Proalar Agreement (MINCYT-DAAD) DA/09/05 and MPI Bioinorganic Chemistry, Germany. V.H.A. was supported by DAAD and Marie Curie (FP7-UE) scholarships. M.E.F., C.D.B. and V.H.A. are researchers from the National Research Council (CONICET) in Argentina. The authors gratefully acknowledge helpful discussions with Prof. Dr. Silvia Braslavsky.
- Abdel-El-Haleem D (2003) Acinetobacter: environmental and biotechnological applications. Afr J Biotechnol 2:71–74Google Scholar
- Cabrol NA, Grin EA, Kiss KT, Ács E, Grigorszky I, Szabò K, Tóth B, Fike DA, Hock AN, Demergasso C, Escudero L, Chong G, Galleguillos P, Grigsby BH, Zambrana Román J, McKay CP, Tambley C (2007) Signatures of habitats and life in earth’s high-altitude lakes: clues to Noachian aqueous environments on mars. In: Chapman M (ed) The geology of mars. Cambridge University Press, pp. 349–370Google Scholar
- Daffonchio D, Borin S, Frova G, Manachini PL, Sorlini C (1998) PCR fingerprinting of whole genomes: the spacers between the 16S and 23S rRNA genes and of intergenic tRNA gene regions reveal a different intraspecific genomic variability of Bacillus cereus and Bacillus licheniformis. Int J Syst Bacteriol 48:107–116PubMedCrossRefGoogle Scholar
- Doetsch RN (1981) Determinative methods of light microscopy. In: Gerhardt P, Murray RGE, Costilow RN, Nester EW, Wood WA, Krieg NR, Phillips GB (eds) Manual of methods for general bacteriology. American Society for Microbiology, Washington, pp 21–33Google Scholar
- Hall TA (1999) BioEdit: a user-friendly biological sequence alignment editor and analysis program for Windows 95/98/NT. Nucleic Acids Symp Ser 41:95–98Google Scholar
- van Gunsteren WF, Billeter SR, Eising AA, Hünenberger PH, Krüger P, Mark AE et al (1996) Biomolecular simulation: the GROMOS96 manual and user guide. Vdf Hochschulverlag AG an der ETH Zürich, ZürichGoogle Scholar