METHANE CLATHRATES ARE LIKELY WIDESPREAD IN OUR SOLAR SYSTEM INCLUDING ON ICY MOONS AND THE MARTIAN SUBSURFACE YET THEIR HABITABILITY REMAINS VIRTUALLY UNSTUDIED. THE PROPOSED RESEARCH WILL INVESTIGATE INTERACTIONS BETWEEN MICROBIAL PROTEINS AND METHANE CLATHRATES. SPECIFICALLY THE PROPOSED WORK WILL TEST THE HYPOTHESIS THAT MICROBES LIVING IN METHANE CLATHRATES ENCODE PROTEINS OPTIMIZED FOR CLATHRATE BINDING AND THAT THESE CLATHRATE BINDING PROTEINS (CBPS) ALTER THE STRUCTURE THERMODYNAMICS AND KINETICS OF METHANE CLATHRATES. OUR RESULTS WILL CONTRIBUTE TO UNDERSTANDING BIO-SIGNATURES OF MICROBIAL COLONIZATION OF METHANE CLATHRATES ON EARTH AND POTENTIALLY ELSEWHERE IN OUR SOLAR SYSTEM. THE PROPOSED RESEARCH WILL: (I) HETEROLOGOUSLY EXPRESS PURIFY ASSAY AND BIOPHYSICALLY CHARACTERIZE CANDIDATE CBPS; (II) QUANTIFY THE EFFECTS OF CBPS ON METHANE CLATHRATE THERMODYNAMICS AND KINETICS OF FORMATION AND DECOMPOSITION IN LABORATORY EXPERIMENTS WITH PRESSURIZED VESSELS; (III) SOLVE CRYSTAL STRUCTURES OF SELECT CBPS AND CHARACTERIZE STATIC INTERACTIONS WITH WATER MOLECULES; (IV) USE HIGH-THROUGHPUT HOMOLOGY MODELING MOLECULAR DYNAMICS AND OTHER COMPUTATIONS TO CHARACTERIZE STRUCTURES AND DYNAMICS OF CBPS; (V) CREATE A PUBLIC DATABASE OF CBPS. THE PROPOSED WORK IS RELEVANT TO THE BIO-SIGNATURES AND LIFE ELSEWHERE EXOBIOLOGY SOLICITATION RESEARCH AREA SPECIFICALLY ESTABLISHMENT OF LIFE UNDER CONDITIONS PREVAILING ON OTHER PLANETARY BODIES AND BASIC RESEARCH ON THE FORMATION AND RETENTION OF BIO-SIGNATURES UNDER NON- EARTH CONDITIONS (E.G. MARS EUROPA) . CLATHRATE-BINDING PROTEINS ARE A NOVEL EXAMPLE OF CO-EVOLUTION OF LIFE AND THE PHYSICAL ENVIRONMENT (NASA ASTROBIOLOGY ROADMAP TOPIC AREA 4). THIS WORK WILL ADDRESS TOPIC 4 FUTURE RESEARCH AREA III: HOW DOES OUR IGNORANCE ABOUT MICROBIAL LIFE ON EARTH HINDER OUR UNDERSTANDING OF THE LIMITS TO LIFE? BY BIOCHEMICALLY VERIFYING THE PHYSIOLOGICAL CHARACTERISTICS OF UNCULTURED ORGANISMS AND BY DIRECTLY LINK[ING] NEWLY DISCOVERED GENOMES TO THE FUNCTIONAL ROLES THE MICROBES PLAY IN A COMMUNITY AND/OR ENVIRONMENT.