title: Thermodynamic analysis of unusually thermostable CutA1 protein from human brain and its protease susceptibility.
abstract: Unusually stable proteins are a disadvantage for the metabolic turnover of proteins in cells. The CutA1 proteins from Pyrococcus horikoshii and from Oryza sativa (OsCutA1) have unusually high denaturation temperatures (Td) of nearly 150 and 100 °C, respectively, at pH 7.0. It seemed that the CutA1 protein from the human brain (HsCutA1) also has a remarkably high stability. Therefore, the thermodynamic stabilities of HsCutA1 and its protease susceptibility were examined. The Td was remarkably high, being over 95 °C at pH 7.0. The unfolding Gibbs energy (ΔG(0)H2O) was 174 kJ/mol at 37 °C from the denaturant denaturation. The thermodynamic analysis showed that the unfolding enthalpy and entropy values of HsCutA1 were considerably lower than those of OsCutA1 with a similar stability to HsCutA1, which should be related to flexibility of the unstructured properties in both N- and C-terminals of HsCutA1. HsCutA1 was almost completely digested after 1-day incubation at 37 °C by subtilisin, although OsCutA1 was hardly digested at the same conditions. These results indicate that easily available fragmentation of HsCutA1 with remarkably high thermodynamic stability at the body temperature should be important for its protein catabolism in the human cells.
authors.affiliation: RIKEN SPring-8 Center, RIKEN, 1-1-1 Kouto, Sayo, Hyogo 679-5148, Japan; Institute for Protein Research, Osaka University, 3-2 Yamada-oka, Suita, Osaka 565-0871, Japan; and National Institute of Agrobiological Sciences, 2-1-2 Kannondai, Tsukuba, Ibaraki 305-0856, Japan.
authors.forename: Bagautdin
authors.initials: B
authors.lastname: Bagautdinov
authors.affiliation: RIKEN SPring-8 Center, RIKEN, 1-1-1 Kouto, Sayo, Hyogo 679-5148, Japan; Institute for Protein Research, Osaka University, 3-2 Yamada-oka, Suita, Osaka 565-0871, Japan; and National Institute of Agrobiological Sciences, 2-1-2 Kannondai, Tsukuba, Ibaraki 305-0856, Japan.
authors.forename: Yoshinori
authors.initials: Y
authors.lastname: Matsuura
authors.affiliation: RIKEN SPring-8 Center, RIKEN, 1-1-1 Kouto, Sayo, Hyogo 679-5148, Japan; Institute for Protein Research, Osaka University, 3-2 Yamada-oka, Suita, Osaka 565-0871, Japan; and National Institute of Agrobiological Sciences, 2-1-2 Kannondai, Tsukuba, Ibaraki 305-0856, Japan.
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Yamamoto
authors.affiliation: RIKEN SPring-8 Center, RIKEN, 1-1-1 Kouto, Sayo, Hyogo 679-5148, Japan; Institute for Protein Research, Osaka University, 3-2 Yamada-oka, Suita, Osaka 565-0871, Japan; and National Institute of Agrobiological Sciences, 2-1-2 Kannondai, Tsukuba, Ibaraki 305-0856, Japan.
authors.forename: Masahide
authors.initials: M
authors.lastname: Sawano
authors.affiliation: RIKEN SPring-8 Center, RIKEN, 1-1-1 Kouto, Sayo, Hyogo 679-5148, Japan; Institute for Protein Research, Osaka University, 3-2 Yamada-oka, Suita, Osaka 565-0871, Japan; and National Institute of Agrobiological Sciences, 2-1-2 Kannondai, Tsukuba, Ibaraki 305-0856, Japan.
authors.forename: Kyoko
authors.initials: K
authors.lastname: Ogasahara
authors.affiliation: RIKEN SPring-8 Center, RIKEN, 1-1-1 Kouto, Sayo, Hyogo 679-5148, Japan; Institute for Protein Research, Osaka University, 3-2 Yamada-oka, Suita, Osaka 565-0871, Japan; and National Institute of Agrobiological Sciences, 2-1-2 Kannondai, Tsukuba, Ibaraki 305-0856, Japan.
authors.forename: Michiyo
authors.initials: M
authors.lastname: Takehira
authors.affiliation: RIKEN SPring-8 Center, RIKEN, 1-1-1 Kouto, Sayo, Hyogo 679-5148, Japan; Institute for Protein Research, Osaka University, 3-2 Yamada-oka, Suita, Osaka 565-0871, Japan; and National Institute of Agrobiological Sciences, 2-1-2 Kannondai, Tsukuba, Ibaraki 305-0856, Japan.
authors.forename: Naoki
authors.initials: N
authors.lastname: Kunishima
authors.affiliation: RIKEN SPring-8 Center, RIKEN, 1-1-1 Kouto, Sayo, Hyogo 679-5148, Japan; Institute for Protein Research, Osaka University, 3-2 Yamada-oka, Suita, Osaka 565-0871, Japan; and National Institute of Agrobiological Sciences, 2-1-2 Kannondai, Tsukuba, Ibaraki 305-0856, Japan.
authors.forename: Etsuko
authors.initials: E
authors.lastname: Katoh
authors.affiliation: RIKEN SPring-8 Center, RIKEN, 1-1-1 Kouto, Sayo, Hyogo 679-5148, Japan; Institute for Protein Research, Osaka University, 3-2 Yamada-oka, Suita, Osaka 565-0871, Japan; and National Institute of Agrobiological Sciences, 2-1-2 Kannondai, Tsukuba, Ibaraki 305-0856, Japan yutani@spring8.or.jp.
authors.forename: Katsuhide
authors.initials: K
authors.lastname: Yutani
mesh_terms: D000595:Amino Acid Sequence; D001921:Brain; D006801:Humans; D008565:Membrane Proteins / Q000737:chemistry*; D008969:Molecular Sequence Data; D058849:Protein Refolding; D055550:Protein Stability; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D058767:Protein Unfolding; D059748:Proteolysis; D017386:Sequence Homology, Amino Acid; D020860:Subtilisin / Q000737:chemistry; D013816:Thermodynamics
chemical_list: C416667:CUTA protein, human; D008565:Membrane Proteins; D020860:Subtilisin
keywords: human CutA1; metabolic turnover of protein; protein stability; thermodynamic parameters; unusually high stability