Molecular mechanisms of adaptation to temperature changes in Antarctic bacteria Shewanella frigidimarina
07-02-2014. CAB THESIS

Laura García Descalzo defended in the Faculty of Pharmacy of the Complutense University of Madrid her thesis work entitled " Molecular mechanisms of adaptation to temperature changes in Antarctic bacteria Shewanella frigidimarina < / b> "directed by Cristina Cid Sánchez obtaining the qualification of Outstanding" Cum Laude ".

Life at low temperatures is a challenge for the cells, which have of dealing with the decrease of enzymatic activity, diffusion of solutes, changes in membrane fluidity, conformation of macromolecules and decrease of translation and replication processes.

Psychrophiles are extremophile organisms that have been adapted satisfactorily to cold environments. The strategies, at the molecular level, used by them are closely related to the chaperone proteins that make up the quality control of the cellular machinery regulating the conformation and activity of other proteins. In this group, heat shock proteins (Hsp) are the most abundant and active whose main representatives are members of the subfamilies Hsp70 (DnaK) and Hsp60 (GroEL). These Hsps correctly fold proteins that are being synthesized and denatured proteins, respond to different types of stress and coordinate macromolecular complexes.

For the study of the contribution of the genome and the environment in the adaptation to temperature this work compares the strategies employed by the Antarctic bacterium Shewanella frigidimarina with a mesophile of the same genus Shewanella oneidensis and another psychrophilic from the same environment but of another genus, Psychrobacter frigidicola.

From cultures of the three species at different temperatures, growth studies were performed, relative quantification of mRNA by quantitative PCR in real time and immunodetection of Hsps Dnak, GroEL, GroES and DnaJ, differential expression studies of proteins (2D-DIGE ) of the total proteome and immunoprecipitation with antibodies against DnaK and GroEL with subsequent separation by bidimensional electrophoresis classic (2DE).

Although the three bacteria have different optimal growth temperatures, the development at 30ºC represents a situation of generalized stress in which the expression of chaperone proteins is induced. of response to thermal and oxidative stress. In addition, in the psicrófilas to 4ºC also increase the antioxidant proteins. The molecular machinery involved in the adaptation to temperature is more complex in S. oneidensis, somewhat simpler in S. frigidimarina and tends to be simplified in P. frigidicola. The S. frigidimarina bacterium, unlike the other two species studied, has a mechanism of adaptation to temperature changes preferentially regulated post-translationally and shows greater versatility in the formation of macromolecular complexes coordinated by DnaK and GroEL establishing them as long one & nbsp; wider temperature range.

 

Fuente: UCC-CAB

 

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