Novel mitochondria-targeted heat-soluble proteins identified in the anhydrobiotic Tardigrade improve osmotic tolerance of human cells
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MAHS-GFP fusion protein localizes to mitochondria in human cells
"Two of them, MAHS and ATPM1, showed mitochondrial localization (Fig. 4a, S3 Fig.)."
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MAHS protein is heat-soluble in vitro
"Although purified MAHS protein was recovered in the soluble fraction after heat treatment, the heat-treated MAHS protein showed relatively slower migration in sodium dodecyl sulphate-polyacrylamide gel electrophoresis (Fig. 4b), indicating a possible conformational change induced by heat treatment."
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MAHS expression improves hyperosmotic tolerance of human HEp-2 cells
"cells expressing MAHS also had significantly increased metabolic activities at 150 mM and 200 mM sucrose. The best improvement by MAHS (~20%) was observed at 200 mM sucrose, which is close to the EC50 value (179 mM) of untransfected cells (Fig. 5)."
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MAHS motif (conserved in tardigrades) forms a predicted amphipathic helix
"Sequence comparison among putative tardigrade MAHS proteins revealed a conserved region in the middle of the protein (S4 Fig.), and this region was partially predicted to form an alpha-helix by PORTER predication software (Fig. 4c-d), potentially with an amphipathic property (Fig. 4e), implying that MAHS proteins have a role similar to that of LEA proteins in anhydrobiosis."
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MAHS has no sequence similarity to known protein families including LEA proteins
"A BLASTP search in non-redundant (nr) database retrieved no sequences, and TBLASTN searches in EST/TSA databases retrieved only two sequences of other tardigrades (e-value < 1); one from the EST database of Hypsibius dujardini and the other from the TSA database of Milnesium tardigradum. No LEA proteins were retrieved in the search and also no LEA-like motif was found by either a InterProScan search or manual inspection."
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MAHS is part of a tardigrade-unique heat-soluble protein repertoire
"To date, three tardigrade-unique heat-soluble protein families have been identified, MAHS, CAHS, and SAHS. Their subcellular localizations are mutually exclusive and together they cover most cellular components: MAHS in the mitochondria, CAHS in the cytoplasm and nucleus, and SAHS in the extracellular space and secretory organelles."