PROIMI   05436
PLANTA PILOTO DE PROCESOS INDUSTRIALES MICROBIOLOGICOS
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
Genome mining revealed coding genes belonging to the photolyase-cryptochrome family in UV-resistant bacteria isolated from High-Altitude Andean Lakes
Autor/es:
ALBARRACÍN V.H.; KURTH D.; FERRER M.G.; ORDOÑEZ O.F.; REVALE S.; MANCINI S.; ROMERO S.; VAZQUEZ M.P.; FARIAS M.E.
Lugar:
COPENHAGEN
Reunión:
Simposio; 14TH INTERNATIONAL SYMPOSIUM ON MICROBIAL ECOLOGY; 2012
Resumen:
High-Altitude Andean Lakes (HAAL) are a disperse group of shallow lakes allocated in the Puna-
High Andes ecoregion above 4,000 m, at Northwestern Argentina. Environmental conditions in the
HAAL are stressful for life, but UV irradiation is giving the greatest pressure on the ecology of its
outstanding microbial diversity. This work presents the analysis of recently made available
genomes of three UV resistant bacterial strains, isolated from these extreme environments and
highlights the presence of coding-genes for members of the photolyase-cryptochrome protein
family (PL-Cry).
We used Acinetobacter sp. Ver3, Exiguobacterium sp. S17, and Nesterenkonia sp. Act20, isolated
from shallow water of Laguna Verde (4,400 m asl), from modern stromatolites and from the
surrounding soil of Laguna Socompa (4,000 m asl), respectively. Maximal UV-B intensity
registered in situ was 10.78 W m-2. Genome sequences were obtained using a whole-genome
shotgun strategy with a 454 GS Titanium pyrosequencer at INDEAR, Argentina. Genomes were
annotated and analyzed in the RAST annotation server. PSI-BLAST and ClustalW were used to
compare and align sequences, and phylogenetic trees were built using Mega4.
Genome sizes were 3,349 Mb for Ver3, 3,139 Mb for S17 and 2,941 Mb for Act20. A total of 3,213
Coding Sequences (CDS) and 66 structural RNAs were predicted in Ver3. Annotation covered 320
RAST subsystems (45%) with 1417 CDS and 55 hypothetical proteins; S17 displayed 3220 CDS
and 49 structural RNAs. Only 43% CDS were annotated in RAST subsystems with 1381 CDS and
73 hypothetical proteins. In Act20, we found 2,666 CDS and 50 structural RNAs. Annotation
covered 302 RAST subsystems (41%) with 1070 CDS and 34 hypothetical proteins.
PL-Cry proteins were found in all the studied genomes, and were classified phylogenetically. These
photolyases fell within three groups: CPD-PLs, photolyase-related proteins (PRPs), and
Cryptochromes. The first two groups were represented in the three organisms studied, while a Cry-
DASH related protein with 72% identity with Exiguobacterium sibiricum was found only in S17.
CPD-PLs from Ver3 and S17 cluster within the Class I-CPD PLs. Interestingly, Act20-PL1 does
not cluster within the group of the so-called actinomycetes CPD-photolyases but as a sister branch
of the plant cryptochromes and Class III CPD-photolyases. Finally, Ver3 PRPs is related to the
newly described FeS bacterial cryptochromes and photolyases (FeS-BCPs). S17 and Act20 also
bear PRPs in the same group, but more distantly related to the known characterized FeS-BCPs.
We have found a rich diversity and complex phylogenetic arrangement of the Cry-PL genes in
different strains from HAAL. These gene products most probably enable them to sense and respond
to the high UV light intensity they suffered in their original environment. Overexpression
experiments are currently processed aiming to demonstrate that these ?extreme? photoreceptors are
functional and effective for these purposes.