title: Structure of the RsbX phosphatase involved in the general stress response of Bacillus subtilis.
abstract: In the general stress response of Bacillus subtilis, which is governed by the sigma factor σ(B), stress signalling is relayed by a cascade of Rsb proteins that regulate σ(B) activity. RsbX, a PPM II phosphatase, halts the response by dephosphorylating the stressosome composed of RsbR and RsbS. The crystal structure of RsbX reveals a reorganization of the catalytic centre, with the second Mn(2+) ion uniquely coordinated by Gly47 O from the β4-α1 loop instead of a water molecule as in PPM I phosphatases. An extra helical turn of α1 tilts the loop towards the metal-binding site, and the β2-β3 loop swings outwards to accommodate this tilting. The residues critical for this defining feature of the PPM II phosphatases are highly conserved. Formation of the catalytic centre is metal-specific, as crystallization with Mg(2+) ions resulted in a shift of the β4-α1 loop that led to loss of the second ion. RsbX also lacks the flap subdomain characteristic of PPM I phosphatases. On the basis of a stressosome model, the activity of RsbX towards RsbR-P and RsbS-P may be influenced by the different accessibilities of their phosphorylation sites.
authors.affiliation: Japan Synchrotron Radiation Research Institute (JASRI/SPring-8), 1-1-1 Kouto, Sayo, Hyogo 679-5198, Japan.
authors.forename: Aik Hong
authors.initials: AH
authors.lastname: Teh
authors.affiliation: Japan Synchrotron Radiation Research Institute (JASRI/SPring-8), 1-1-1 Kouto, Sayo, Hyogo 679-5198, Japan.
authors.forename: Masatomo
authors.initials: M
authors.lastname: Makino
authors.affiliation: Japan Synchrotron Radiation Research Institute (JASRI/SPring-8), 1-1-1 Kouto, Sayo, Hyogo 679-5198, Japan.
authors.forename: Takeshi
authors.initials: T
authors.lastname: Hoshino
authors.affiliation: Japan Synchrotron Radiation Research Institute (JASRI/SPring-8), 1-1-1 Kouto, Sayo, Hyogo 679-5198, Japan.
authors.forename: Seiki
authors.initials: S
authors.lastname: Baba
authors.affiliation: Japan Synchrotron Radiation Research Institute (JASRI/SPring-8), 1-1-1 Kouto, Sayo, Hyogo 679-5198, Japan.
authors.forename: Nobutaka
authors.initials: N
authors.lastname: Shimizu
authors.affiliation: RIKEN SPring-8 Center, 1-1-1 Kouto, Sayo, Hyogo 679-5148, Japan.
authors.forename: Masaki
authors.initials: M
authors.lastname: Yamamoto
authors.affiliation: Japan Synchrotron Radiation Research Institute (JASRI/SPring-8), 1-1-1 Kouto, Sayo, Hyogo 679-5198, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Kumasaka
mesh_terms: D000595:Amino Acid Sequence; D001412:Bacillus subtilis / Q000201:enzymology* / Q000502:physiology; D001426:Bacterial Proteins / Q000737:chemistry*; D003460:Crystallization; D008969:Molecular Sequence Data; D010749:Phosphoprotein Phosphatases / Q000737:chemistry*; D017386:Sequence Homology, Amino Acid; D013312:Stress, Physiological
chemical_list: D001426:Bacterial Proteins; D010749:Phosphoprotein Phosphatases
keywords: dephosphorylation; environmental stress; manganese binding; protein phosphatase; signalling protein; stressosome