GenePage for the etk gene of Escherichia coli K-12

Primary Gene Name: etk
EcoGene Accession Number: EG11826
K-12 Gene Accession Number: ECK0972
MG1655 Gene Identifier: b0981
Gene Name Mnemonic: E. coli protein Tyrosine Kinase
Alternate Gene Symbols: yccC
Description: Tyrosine-protein kinase, required for O-antigen capsule formation; autokinase; polymyxin resistance
  # bp Upstream # bp Downstream
Verified Start MW: 81241.68 ---------726 aa Pre-Run BlastP UniProt
Pre-Run BlastP NR+Env
Left End: 1042030
Left Intergenic Region

Name: appA_etk

Length: 114 bp gap

Orientation: Convergent

Left_end: 1041916

Right_end: 1042029

Centisome: 22.45

Genomic Address
Minute or Centisome (%) = 22.45
Right End: 1044210
Right Intergenic Region

Name: etk_etp

Length: 19 bp gap

Orientation: Codirectional-

Left_end: 1044211

Right_end: 1044229

Centisome: 22.50

E. coli K-12 Etk is de-phosphorylated by the Etp phosphatase in vitro (Vincent, 2000). E. coli K-12 does not produce O-antigen capsule polysaccharide because the cryptic gfcABCDE-etp-etk operon is silenced by IS1D in the promoter region (Peleg, 2005). Etk is required for O-antigen capsule formation in enteropathogenic E. coli (EPEC) (Peleg, 2005). Partial phosphorylation of Etk Y574 has been experimentally confirmed by using 3,5-difluorotyrosine as a 19 F NMR probe; a proposed interaction between Y574 and R614 was confirmed (Li, 2013). Etp Y121 is shown to be phosphorylated by an unknown kinase, not Etk or Wzc (Nadler, 2012). The Etk paralog Wzc is autophosphorylated intra-molecularly at Y569 and inter-molecularly at Y708, Y710, Y711, Y713 and Y715, as experimentally demonstrated by site-directed mutagenesis and in vitro kinase assays; all six phosphorylated Wzc tyrosines are conserved in Etk (Y574, Y713, Y715, Y717, Y718 and Y720 (Grangeasse, 2002). A crystal structure of Etk did not show tyrosine phosphates due to rapid dephosphorylation during the sample preparation; structure-guided mutagenesis with enzymatic and phenotypic characterization of the K-12 Etk kinase supports a proposed Y574-R614 interaction and molecular switching mechanism (Lee, 2008). Experimental evidence and molecular dynamics simulations support the molecular switch interaction between Y574 and R614 and also identifies R572 as influencing the rotation of P-Y574 (Lu, 2009). Like its paralog Wzc, Etk is a membrane-bound protein with two transmembrane segments flanking a short N-terminal cytoplasmic region, a large periplasmic domain, and a large C-terminal catalytic cytoplasmic domain (Doublet, 2002; Daley, 2005). The O-antigen capsule is also known as the group 4 capsule (G4C).

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