From molecule to cell: Deciphering what makes Pyrococcus yayanosii CH1 a strict piezophile

Informations

Funding country

France

Acronym

LIVING DEEP

URL

-

Start date

1/1/2011

End date

-

Budget

720,000 EUR

Fundings

Abstract

Our project aims to establish the genetic basis of high hydrostatic pressures (HHP) adaptation, or piezophily, by investing the influence of HHP on cell molecular dynamics, genome expression, metabolic capabilities and enzymatic structure and activity of microbial models originating from oceanic hydrothermal vents. The most extensive biodiversity on Earth is encompassed by the unicellular prokaryotes. These organisms are found in virtually any environment on our planet, including deeply underground and at the bottom of the deepest oceans. They may well make up as much as 70% of all cells, and be responsible for 50% of primary biomass production. The deep-biosphere represents the largest ecosystem on Earth. It is located in the continental underground and in the oceans below 1000 m in depth. These oligotrophic biotopes are under high hydrostatic pressures (HHP). They are still poorly characterized in terms of diversity or adaptation to pressure. There is growing interest in the vast microbial biosphere within the Earth’s crust, with the awareness that microbes living in such settings concurrently experience significantly high pressures and temperatures. This interest is reflected in recent projects associated with deep biosphere studies, including the NSF Ocean Observatories Initiative and the Alfred P. Sloan Foundation Deep Carbon Observatory. The multi-disciplinary research focuses on the Earth’s poorly understood deep carbon cycle, and the largely unknown role of deep biology on this cycle, in the context also of critical societal concerns related to energy, environment and climate. Amongst deep-biosphere biotopes, the hydrothermal vents may be the most intriguing; they were shown, despite being hot oligotrophic and HHP environments, to harbor abundant primary productivity and diversity. Their primary production is based exclusively on the anaerobic chemical harvest of the energy of the geological fluids seeping through the ocean floor. Thus, they represent the only photysnthesis-independent ecosystems on Earth. We propose to address the issue of HHP-adaptation by regrouping five research teams with complementary expertise and skills, to work mainly on the HHP-adaptation in the only hyperthermophilic strict piezophile known so far, Pyrococcus yayanosii. The five tasks of the proposal correspond to the different steps of an analytic pipeline to investigate the impact of HHP on piezophilic hyperthermophiles. Using neutron scattering combined with a microbial culture approach we shall measure cell fitness and performance, as reflected in molecular dynamics of piezophile vs non piezophile prokaryotes, in response to HHP (task 1). Genome mining will identify potential specific adaptive motifs in piezophilic proteins (task 2). Genome sequences alone will not provide a full understanding of piezophilic character; we shall quantify the role of gene regulation (transcriptomics) and protein production (proteomics) in HHP-adaptation (task 3). The proteins resulting from tasks 2 and 3 will be characterized by in-situ spectroscopy (Raman, IR, X-ray) (task 5), and selected ones (depending on over-expression and solubility) will be studied by enzymology and X-ray crystallography in task 4, to characterize their structure-function relations. The model proteins (MalDH/LDH, aminopeptidases) will also be studied to compare structures, molecular dynamics and enzymatic parameters in order to identify piezophilic traits (task 4). In summary, this proposal aims to: i) identify molecular signatures, ii) characterize structural and dynamic adaptation in piezophilic proteins, iii) decipher the evolutionary path to HHP-adaptation, iv) map regulatory and metabolic networks, and v) identify markers for piezophily. The project is a first step in identifying markers for characterizing the abundance of deep-biosphere life, and provides important data that could be used to engineer enzymes of high biotechnological potential.