X-ray structure of HPr kinase: a bacterial protein kinase with a P-loop nucleotide-binding domain.
HPr kinase/phosphatase (HprK/P) is a key regulatory enzyme controlling carbon metabolism in Gram- positive bacteria. It catalyses the ATP-dependent phosphorylation of Ser46 in HPr, a protein of the phosphotransferase system, and also its dephosphorylation. HprK/P is unrelated to eukaryotic protein kinases, but contains the Walker motif A characteristic of nucleotide-binding proteins. We report here the X-ray structure of an active fragment of Lactobacillus casei HprK/P at 2.8 A resolution, solved by the multiwavelength anomalous dispersion method on a seleniated protein (PDB code 1jb1). The protein is a hexamer, with each subunit containing an ATP-binding domain similar to nucleoside/nucleotide kinases, and a putative HPr-binding domain unrelated to the substrate-binding domains of other kinases. The Walker motif A forms a typical P-loop which binds inorganic phosphate in the crystal. We modelled ATP binding by comparison with adenylate kinase, and designed a tentative model of the complex with HPr based on a docking simulation. The results confirm that HprK/P represents a new family of protein kinases, first identified in bacteria, but which may also have members in eukaryotes.
Fieulaine
S
S
Laboratoire d'Enzymologie et Biochimie Structurales, UPR 9063, CNRS, 91198 Gif sur Yvette, France.
Morera
S
S
Poncet
S
S
Monedero
V
V
Gueguen-Chaignon
V
V
Galinier
A
A
Janin
J
J
Deutscher
J
J
Nessler
S
S
D000244:Adenosine Diphosphate / Q000378:metabolism*; D000255:Adenosine Triphosphate / Q000378:metabolism*; D000595:Amino Acid Sequence; D001426:Bacterial Proteins; D001665:Binding Sites; D018360:Crystallography, X-Ray; D007780:Lacticaseibacillus casei / Q000201:enzymology; D008958:Models, Molecular; D008969:Molecular Sequence Data; D010731:Phosphoenolpyruvate Sugar Phosphotransferase System / Q000737:chemistry / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases / Q000737:chemistry* / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism; D020836:Protein Structure, Quaternary; D017386:Sequence Homology, Amino Acid
D001426:Bacterial Proteins; D000244:Adenosine Diphosphate; D000255:Adenosine Triphosphate; D010731:Phosphoenolpyruvate Sugar Phosphotransferase System; C030182:phosphocarrier protein HPr; C110847:HPr kinase; D017346:Protein Serine-Threonine Kinases