Identification and biochemical characterization of a novel PP2C-like Ser/Thr phosphatase inE. coli

Abstract

15In bacteria, signaling phosphorylation is thought to occur primarily on His and Asp 16 residues. However, phosphoproteomic surveys in phylogenetically diverse bacteria over 17 the past decade have identified numerous proteins that are phosphorylated on Ser and/or 18 Thr residues. Consistently, genes encoding Ser/Thr kinases are present in many bacterial 19 genomes such as E. coli, which encodes at least three Ser/Thr kinases. Since Ser/Thr 20 phosphorylation is a stable modification, a dedicated phosphatase is necessary to allow 21 reversible regulation. Ser/Thr phosphatases belonging to several conserved families are 22 38 requires the action of a partner Ser/Thr phosphatase to remove the modification. Although 39 a number of Ser/Thr kinases have been reported in E. coli, no partner Ser/Thr 40 phosphatases have been identified. Here, we biochemically characterize a novel Ser/Thr 41 phosphatase that acts to dephosphorylate a Ser/Thr kinase that is encoded in the same 42 operon. 43 65 like Ser/Thr phosphatases (eSTPs). Some of these proteins have been characterized 66 biochemically and structurally, with these studies confirming their general similarity to their 67 eukaryotic counterparts. Eukaryotic Ser/Thr protein phosphatases are divided into two 68 classes, either phosphoprotein phosphatases (PPP) or metal dependent protein 69 a protein phosphatase, Pph3, from Myxococcus xanthus. J Bacteriol 193:2657-61. 595 41. Halbedel S, Busse J, Schmidl SR, Stulke J. 2006. Regulatory protein 596 phosphorylation in Mycoplasma pneumoniae. A PP2C-type phosphatase serves 597 to dephosphorylate HPr(Ser-P). J Biol Chem 281:26253-9. 598

Escherichia coli YegI is a novel Ser/Thr kinase lacking conserved motifs that localizes to the inner membrane

“…Our laboratory previously identified a novel PP2C‐like phosphatase in the E. coli genome encoded by the pphC ( yegK ) gene [13]. Often, phosphatases of this class are found proximal to eukaryotic‐like Ser/Thr kinases (eSTKs) [7].…”

“…We previously demonstrated that a His 6 ‐tagged version of YegI is capable of autophosphorylation [13] despite the absence of three of the ten absolutely conserved residues (Fig. 1).…”