Urease genes

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

DNA from the capsule filters was extracted for whole community 16S rDNA and urease gene characterization using a umdified sucrose lysis filter extraction method (P, 10). Briefly, 40 mL of lysis buffer (20 mM EDTA, 400MNaCl, 50 mM Tris, and 0.75 M sucrose, pH 9), 4 mL 10% SDS, and... 

Figure 2. Urease genes amplified from seven unique, pure bacterial cultures isolated from Snake River Plain Aquifer groundwater. Lanes A through G show the characteristic PCR product (ca. 400 base pair length) amplified from these...

Figure 4. Urease gene products amplified Jrom complex microbial communities filtered from Second Owsley groundwater before (A), during (B), and after (C) the field experiment. Different lanes within one of the sampling times represent replicate filters obtained from the well.

Tyler, T. L. Watwood, M. E. Colwell, F. S. Characterization of Urease Genes in Subsurface Microbial Communities, Annual Meeting of the American Society for Microbiology, abstract, 2002. 

The most likely explanation for the increase in urease activity seen with acidification is that there is a urea transporter in the bacteria. The urease gene cluster contains seven genes. There is a promoter followed by genes encoding the structural subunits, UreA and UreB. There is then a second promoter and then genes encoding Urel, -E, -F, -G, and -H. The last four are genes required for the assembly of active urease from the UreA-B apoenzyme by insertion of nickel, an essential cofactor in urease activity. UreE and -G and UreF and -H form heterodimers, and then a complex with UreA-B and nickel insertion occurs. 

Ferrero RL, Labigne A. Organization and expression of the Helicobacter pylori urease gene cluster in Helicobacter pylori biology and clinical practice. In Goodwin CS, Worley BW, eds. Florida CRC Press, 1993 171-195. 

The organism contains enzymes for glucose metabolism, lacks p galac-tosidase (hence is unable to metabolize lactose), some of the enzymes of the Krebs cycle (no isocitrate dehydrogenase), and most important, the urease gene cluster encoding ureA and ureB (urease) and ureE,F,G,H and I... 

McGee DJ, May CA, Garner RM, et al. 1999. Isolation of Helicobacter pylori genes that modulate urease activity. J Bacteriol 181 2477-84. 

Mobley HLT, Garner RM, Bauerfeind R 1995. Helicobacter pylori nickel-transport gene AA synthesis of catalytically active urease in Escherichia coli independent of growth conditions. Mol Microbiol 16 97-109. 

In addition, urease is inhibited by a variety of agents including fluoride and disulfldes, as observed recently in the acetohydroxamate-inhibited C319A variants of K. aero-genes urease. It is proposed that this mode of inhibition involves coordination of the inhibitor to only one nickel center, while another involves the inhibitor bridging the dinickel center. Urease is slowly inhibited by fluoride in both the presence and absence of substrate, and fluoride binding rates are directly proportional to inhibitor concentration. Fluoride inhibition is pH-dependent due to a protonation... 

Urease was the first enzyme whose functional structure was elucidated (see Zimmer, 2000). All together seven polypeptides are needed for functional urease. UreC is the major functional subunit of urease and is large (Collier et al, 1999) relative to the ureA and ureB subunits aU are highly conserved. In addition, four accessory genes, ureD, ureE, ureF, ureG, are needed for enzyme assembly. 

Buchners fermentation of sugar from yeast extracts Sumner s crystallization of urease Flemming s discovery of chromosomes Mendel s characterization of genes Miescher s isolation of nucleic acids Watson and Crick s stmcture of DNA... 

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