Klebsiella urease

Colpas GJ, Brayman TG, Ming L-J, Hausinger RP. 1999. Identification of metalbinding residues in the Klebsiella aerogenes urease nickel metallochaperone, UreE. Biochemistry 38 4078-88. 

The crystal structure of urease form Klebsiella aerogenes has recently been determined (47). The two nickel(II) ions in the active site are... 

Jack bean urease is a trimer or hexamer of identical 91-kDa subunits while that of the bacterium Klebsiella has an (a(32y2)2 stoichiometry. Nevertheless, the enzymes are homologous and both contain the same binickel catalytic center (Fig. 16-25).435-4373 The three-dimensional structure of the Klebsiella enzyme revealed that the two nickel ions are bridged by a carbamyl group of a carbamylated lysine. Like ribulose bisphos-phate carboxylase (Fig. 13-10), urease also requires C02 for formation of the active enzyme.438 Formation of the metallocenter also requires four additional proteins, including a chaperonin and a nickel-binding protein.438 439... 

Urease (urea amidohydrolase) is an enzyme first identified over a hundred years ago in bacterial extracts [22], The presence of urease is a virulence factor for some pathogenic bacteria [23,24], It is now known to occur also in plants, fungi, and invertebrates (see [24,25] for reviews). Urease from jack bean was the first enzyme to be crystallized, in 1926. Almost 50 years later its metal content was reexamined and it was found to contain two atoms of nickel per subunit [26]. Finally in 1995 the crystal structure of the enzyme from the enteric bacterium Klebsiella aerogenes was determined [27], Amino-acid sequence comparisons predict that the structures of the plant and bacterial enzymes are similar, although with different subunit arrangements. 

Variable temperature magnetic circular dichroism (MCD) studies have revealed similar electronic and magnetic properties for the nickel centres in Jack bean and Klebsiella aerogenes urease. Native and 2-mercaptoethanol and acetohydroxamic inhibited forms of both enzymes have been investigated and in each case the energy of the temperature dependent MCD for the nickel(II) d-d transitions indicates octahedral coordination with mainly oxygen donors. 

Jabri E et al (1995) The crystal structure of urease from Klebsiella aerogenes. Science 268 998-1004 PDBID 2KAU... 

The X-ray crystallographic studies of the enzyme isolated from Klebsiella aerogenes reveals an active site composed of a dinickel center with 3.5-A Ni- Ni separation. A schematic view of the active site of urease isolated from K. aerogenes is... 

Three Ni-confaintng enzymes (see Nickel Enzymes Cofactors) appear to utilize Ni metallochaperones for enzyme activation. UreE appears to function in NP+ delivery to urease. The Klebsiella aerogenes protein binds 6 Ni per dimer, whereas that from Bacillus pasteurii binds a single Ni per dimer. The metal content differences arise from a His-Asp-His sequence near the middle and a histidine-rich region at the carboxyl terminus of the former protein. Truncated K aerogenes UreE protein, missing the His-rich... 

Lee MH, Pankratz HS, Wang S, Sgott RA, Ein-negan mg, Johnson MK, Ippolito JA, Christianson DW and Hausinger RP (1993) Purification and characterization of Klebsiella aerogenes UreE protein a nickel-binding protein thatfunc-tions in urease metallocenter assembly. Protein Sd 2 1042-1052. 

Sequence of the Klebsiella aerogenes urease genes and evidence for accessory proteins facilitating nickel incorporation. J Bacteriol 172 5837-5843. 

Song HK, Muleooney SB, Hubee R and Hau-siNGEE RP (2001) Crystal structure of Klebsiella aerogenes UreE, a nickel-binding metallochaperone for urease activation. J Biol Chem 276 49359-49364. 

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