Protein structure, stability, and dynamics in non-terrestrial systems

IDEA: I-2021-02118

Proteins are the cornerstone of all life found on Earth, with their structural and functional diversity and ease in modification and turnover, making them ideal for biological processes. Their capabilities and the abiotic availability of chemical precursors make it logical to postulate that proteins may form a universal construct of life. However, there has been limited research into how proteins could operate in solvent conditions found on other bodies in our Solar System. Understanding how proteins could function in these environments will help address whether other bodies in our solar system could host protein-based life. We propose to investigate the solvent-protein compatibility of two Solar System locations, Enceladus and Mars. Using data from the Cassini probe and the upcoming Mars2020 and ExoMars rovers, this proposal aims to replicate these bodies' solvent conditions to create a solvent modelling system. For Enceladus, we aim to replicate the subterranean ocean that was sampled by the Cassini probe utilising the Ion and Neutral Mass Spectrometer and Cosmic Dust Analyser. For the Mars model, we will replicate the solvent environment of the potential ocean that existed in the northern hemisphere within which the Rosalind Franklin and Perseverance rover will land. By introducing proteins to these two modelling systems, this research will assess if protein-based life is compatible with the current conditions on Enceladus and the early conditions on Mars. This research will mature our current understanding of the biochemical limits of protein functionality while also pushing the boundary of our understanding as to what areas of the solar system could be compatible with life. An approach applying the astrochemical data acquired from Enceladus or Mars to protein biochemical studies has never been previously attempted, thus demonstrating the novelty this study will bring to the astrobiological and bioscientific fields.

Introduction

Proteins lie at the very root of every structural and functional capability in nature. In this European Space Agency-ISSET sponsored research, we use protein-solvent compatibility as a tool to gauge the suitability of extra-terrestrial water environment for the emergence of protein-based life. Through collaboration with the NASA Cassini INMS team, we apply data from the Cassini Enceladus flybys to recreate solvent models within which we test the function, folding and solubility of short proteins, all of which would be required for life to emerge in such an environment. In 2023, with the launch of the Rosalind Franklin rover and in collaboration with the ESA Rosalind Franklin RLS team, we will also apply this methodology to investigating how conducive early Martian oceans would have been with the emergence of protein chemistry. Through this, we hope to constrain the limits of habitability and the environment's potential to support abiogenesis. Back on Earth, we also seek to expand our knowledge on the emergence of protein function and folding during abiogenesis on Earth approximately 4 billion years ago. This research is backed by funding from the International Space School Educational Trust, The European Space Agency and the Department of Biochemistry at the University of Oxford.

Motivation

Water is considered a prerequisite for any carbon-based life similar to that observed on Earth. Following the observations of indicators of ancient water flows on Mars and an underwater ocean on Enceladus, some in the academic community have suggested these environments could be suitable for life. However, the constituents of water environments have important implications on the biocompatibility of that environment, with several variables creating protein-destabilising conditions that can make areas hostile for life as we know it. This proposal seeks to investigate how the composition of other water-bearing planetary locations could impact protein conformation and chemical stability when immersed within them and thus identify how suitable each environment would be to support protein-based, Earth-like life. It shall achieve this by evaluating the water environment in detail on two bodies within the solar system where standing water exists now or is considered very likely to have once existed. This approach will evaluate if the solvent conditions within these locations would be compatible with proteins which are a fundamental functional and structural component of biology on Earth. For any environment to be habitable for Earth-like life, it must be compatible with protein functionality. In extreme conditions on Earth, organisms make necessary adaptions to their protein structure to retain activity. However, Mars and Enceladus possess many extreme characteristics that could produce a destabilising environment for even the most essential elements of protein structure; helices and beta sheets. Examples of these for Enceladus are its highly alkaline (≈pH 9-10) and reducing water that intermixes with hot mineral-rich vent systems producing local temperatures of 150-200°C. On the other hand, Mars likely had an acidic, high salinity composition with an abundance of Iron salts. By replicating the solvent conditions on Enceladus and Mars, we will assess how protein activity is impacted within these environments through direct replication of the solvent conditions. The subject matter addressed within this research strikes at the core of astrobiology: the limits of life, particularly protein-based life. By analysing the capability of environments to support protein function, we will refine our understanding of the limits of the environments that could support protein-based life and the suitability of these locations for further exploration.

Collaborators

Professor. Jack Hunter Waite

Professor J. Hunter Waite is the Program Director of the Center for Excellence in Analytical Mass Spectrometry at Southwest Research Institute in San Antonio, Texas. His expertise involves the application of ion and neutral mass spectrometry in the space environment. His early work involved the study of the Earth's topside ionosphere and magnetosphere with ion mass spectrometry as a participant in the Dynamics Explorer mission. Starting in the early 1990's he became involved in the Cassini Huygens mission, where he served as the Facility Team Leader for the Ion and Neutral Mass Spectrometer from 1992 to the end of the mission in 2017. His research during this time period focused on the composition of Titan's upper atmosphere, the plumes of Enceladus, and the infall and interaction of ring material with Saturn's upper atmosphere. During this same time period, he was also involved as a co-Investigator on ESA's Rosetta mission participating in the analysis of cometary volatiles using the Rosina mass spectrometers. Dr Waite is presently involved in the development of the Mass Spectrometer for Planetary Exploration that will fly onboard NASA's Clipper mission to Europa. He also participates in the study of Jupiter's atmosphere and aurora as a co-Investigator on NASA's Juno mission. He has training experience as a Professor at the University of Michigan in Atmospheric Science from 2000 to 2006. He is presently an Adjoint Professor at the University of Texas San Antonio chairing the research of six graduate students from 2000 to the present.

Dr. Jihao Hua

Jihua Hao is a senior research scientist at the Department of Geochemistry and Planetary Sciences, University of Science and Technology of China. He is also an affiliated research scientist at Blue Marble Space Institute of Science. He got his PhD in Geochemistry at Johns Hopkins University from 2012 to 2016. Then, he had two periods of postdoctoral research at the University of Lyon 1, France and Rutgers University, USA, respectively. His research interests include early earth surface environments, origin and early evolution of life, water chemistry of icy moon oceans, photogeochemistry, and high temperature and pressure aqueous geochemistry.

Professor Fernando Rull

Prof. Fernando Rull is an expert on Raman spectroscopy. He is internationally recognized for his work on many applications of this technique and combination with IR and LIBS to mineralogy, industry and cultural heritage. In the last two decades Prof. Rull devoted his interest in developing instrumentation for space exploration. He is PI of the Raman instrument onboard Exomars Rosalind Franklin’s rover, also PI institutional and responsible for the SuperCam calibration system onboard Mars 2020 Perseverance rover and Co-PI of the RAX instrument under development for MMX mission to Phobos. With his team at the ERICA-UVA group also developed Raman and Raman-LIBS prototypes for terrestrial applications with particular interest on the in-situ study of potential terrestrial analogues. This work is complemented with the development of important databases and several tools for data treatment.

Dr Marjorie Fournier

Dr Marjorie Fournier is the head of the Advanced Proteomics Facility in the department of New Biochemistry at the University of Oxford. She is an interdisciplinary research scientist expert in functional proteomics using mass spectrometry-based quantitative proteomics and post-translational modifications analysis to characterise molecular mechanisms involved in cellular adaptation. She had gained expertise in proteomics and large scale data analysis in the proteomics research center led by Prof Michael Washburn at the Stowers Institute of Medical Research (Kansas City, USA). Her research contributions involve notably the understanding of molecular adaptation of anaerobes to oxygen and the role of metabolic regulated post-translational modifications in maintaining genome stability funded by FP7 Marie-Curie actions.

Dr Jon Wade

Dr Jon Wade's research interests have been focused around the consequences of planetary core formation and the mark this leaves on a planets rocky mantle. His initial academic contributions reconciled a long-standing problem in geochemistry, the apparent low abundance of Nb in the silicate Earth. This demonstrated that the Nb content of the Earth's mantle is depleted by planetary core formation which sequesters Nb into the core, an element hitherto thought to be unaffected by metal segregation (Wade & Wood, Nature 2001). Building on this, he developed a chemical model of terrestrial accretion and segregation of the core (EPSL, 2005) and a review paper expanding on this work (Nature, 2006). More recent work has explored the geochemical implications of lunar formation and the role of iron in determining the 'lifespan' of water on the Martian surface (Wade et al. Nature 2017), and on the habitability of exoplanetary surfaces (APJ, 2021). His current interests also involve the optimisation of high spatial resolution analytical techniques for elemental analyses – both electron beam based and ICP-MS of micro particulates and cellular material. These techniques being required to explore the vital response of organisms to the changing bio-availability of iron, itself a response of the oxygenation of the terrestrial atmosphere ~2.6 billion years ago and future climate change.