title: Pyrophosphate hydrolysis in the extremely halophilic archaeon Haloarcula japonica is catalyzed by a single enzyme with a broad ionic strength range.
abstract: The soluble protein fraction of the extremely halophilic archaeon Haloarcula japonica exhibits substantial inorganic pyrophosphate (PPi) hydrolysis activity in the presence of 2-4 M NaCl (Wakai et al, J Biol Chem 288:29247-29251, 2013), which provides high ionic strength (2-4). In this study, much higher PPi hydrolysis activity was unexpectedly detected, even with 0 M NaCl in the presence of 100-200 mM MgSO4, providing a much lower ionic strength of 0.4-0.8, in the same protein fraction. Na+and Mg2+ions were required for activity under high and low ionic strength conditions, respectively. A recombinant H. japonica pyrophosphatase (HjPPase) exhibited PPi hydrolysis activity with the same broad ionic strength range, indicating that the activity associated with such a broad ionic strength range could be attributed to a single enzyme. Thus, we concluded that the broad ionic strength range of HjPPase may contribute to adaptation for both Na+and Mg2+which are abundant but variable in the unstable living environments of H. japonica.
authors.affiliation: Graduate School of Biosphere Science, Hiroshima University, 1-4-4 Kagamiyama, Higashi-Hiroshima, Hiroshima, 739-8528, Japan. wakaists@pegasus.kobe-u.ac.jp.|Graduate School of Science, Technology, and Innovation, Kobe University, 1-1 Rokkodai, Nada, Kobe, 657-8501, Japan. wakaists@pegasus.kobe-u.ac.jp.
authors.forename: Satoshi
authors.initials: S
authors.lastname: Wakai
authors.affiliation: Graduate School of Biosphere Science, Hiroshima University, 1-4-4 Kagamiyama, Higashi-Hiroshima, Hiroshima, 739-8528, Japan.
authors.forename: Akihiro
authors.initials: A
authors.lastname: Abe
authors.affiliation: Graduate School of Biosphere Science, Hiroshima University, 1-4-4 Kagamiyama, Higashi-Hiroshima, Hiroshima, 739-8528, Japan.
authors.forename: Sotaro
authors.initials: S
authors.lastname: Fujii
authors.affiliation: Department of Chemistry and Environmental Technology, School of Engineering, Kinki University, Umenobe Takaya 1, Higashi-Hiroshima, Hiroshima, 739-2116, Japan.
authors.forename: Kaoru
authors.initials: K
authors.lastname: Nakasone
authors.affiliation: Graduate School of Biosphere Science, Hiroshima University, 1-4-4 Kagamiyama, Higashi-Hiroshima, Hiroshima, 739-8528, Japan. sambongi@hiroshima-u.ac.jp.
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Sambongi
mesh_terms: D019843:Archaeal Proteins / Q000737:chemistry / Q000378:metabolism*; D011756:Diphosphates / Q000378:metabolism*; D000071251:Extreme Environments; D019613:Haloarcula / Q000201:enzymology* / Q000378:metabolism; D009994:Osmolar Concentration; D011755:Pyrophosphatases / Q000737:chemistry / Q000378:metabolism*; D054712:Salinity
chemical_list: D019843:Archaeal Proteins; D011756:Diphosphates; C107241:diphosphoric acid; D011755:Pyrophosphatases
keywords: Haloarcula japonica; Halophilic; Ionic strength; Pyrophosphatase; Pyrophosphate hydrolysis