ISSN:
1432-072X
Keywords:
Key words:Staphylococcus– Urease – Nickel – Nucleotide sequence – Phenylmethanesulfonyl fluoride (PMSF) – Enzyme subunits – Serine protease
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
Notes:
Abstract. DNA sequence analysis of the structural urease genes from Staphylococcus xylosus revealed that three enzyme subunits are encoded in the order of 11 000, 15 400 and 61 000 (mol. mass), which correspond to the single polypeptide chain of jack bean urease (90 800). Comparing the deduced amino acid sequence of S. xylosus urease with the amino acid sequence of jack bean urease an overall portion of 56% identical residues was found. For S. xylosus urease a subunit structure of (αβγ)4 was proposed, based on the comparison of the deduced amino acid content of the enzyme subunits with the total amino acid content of the purified enzyme. The staphylococcal enzyme contained no cysteine, as deduced from DNA sequence and confirmed by the determination of the total amino acid content in the purified enzyme. Instead of cysteine, known to be catalytically essential in the plant enzyme, and conserved among all bacterial ureases analyzed so far, threonine was found in S. xylosus. This amino acid-exchange was located within a highly conserved domain of 17 amino acids, supposed to be part of the active site. Sequence analysis of the respective region of Staphylococcus saprophyticus urease showed that it also contains threonine instead of cysteine. In contrast to jack bean urease S. xylosus urease was not affected by the SH-group inhibitor dipyridyl disulfide but was completely inhibited by the serine protease inhibitor phenylmethanesulfonyl fluoride. The presented results indicate that in these staphylococcal strains urea hydrolysis might function in a manner similar to the peptide bond cleavage by chymotrypsin.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00288947
Permalink
