3w40

Publication Abstract from PubMed

In the general stress response of Bacillus subtilis, which is governed by the sigma factor sigma(B), stress signalling is relayed by a cascade of Rsb proteins that regulate sigma(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 beta4-alpha1 loop instead of a water molecule as in PPM I phosphatases. An extra helical turn of alpha1 tilts the loop towards the metal-binding site, and the beta2-beta3 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 beta4-alpha1 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.

Structure of the RsbX phosphatase involved in the general stress response of Bacillus subtilis.,Teh AH, Makino M, Hoshino T, Baba S, Shimizu N, Yamamoto M, Kumasaka T Acta Crystallogr D Biol Crystallogr. 2015 Jun;71(Pt 6):1392-9. doi:, 10.1107/S1399004715007166. Epub 2015 May 23. PMID:26057679^[5]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.