21148732
not annotated - annotated - LINNAEUS only
Functional and phylogenetic analysis of ureD in Shiga toxin-producing Escherichia coli.
Enterohemorrhagic Escherichia coli (EHEC) is a food-borne pathogen that can cause severe health complications and utilizes a much lower infectious dose than other E. coli pathotypes. Despite having an intact ure locus, ureDABCEFG, the majority of EHEC strains are phenotypically urease negative under tested conditions. Urease activity potentially assists with survival fitness by enhancing acid tolerance during passage through the stomach or by aiding with colonization in either human or animal reservoirs. Previously, in the EHEC O157:H7 Sakai strain, a point mutation in ureD, encoding a urease chaperone protein, was identified, resulting in a substitution of an amber stop codon for glutamine. This single nucleotide polymorphism (SNP) is observed in the majority of EHEC O157:H7 isolates and correlates with a negative urease phenotype in vitro. We demonstrate that the lack of urease activity in vitro is not solely due to the amber codon in ureD. Our analysis has identified two additional SNPs in ureD affecting amino acid positions 38 and 205, in both cases determining whether the encoded amino acid is leucine or proline. Phylogenetic analysis based on Ure protein sequences from a variety of urease-encoding bacteria demonstrates that the proline at position 38 is highly conserved among Gram-negative bacteria. Experiments reveal that the L38P substitution enhances urease enzyme activity; however, the L205P substitution does not. Multilocus sequence typing analysis for a variety of Shiga toxin-producing E. coli isolates combined with the ureD sequence reveals that except for a subset of the O157:H7 strains, neither the in vitro urease-positive phenotype nor the ureD sequence is phylogenetically restricted.
Ann file
T1 Species 70 86 Escherichia coli
N1 Reference T1 Taxonomy:562
T2 Species 108 124 Escherichia coli
N2 Reference T2 Taxonomy:562
T3 Species 126 130 EHEC
N3 Reference T3 Taxonomy:562
T4 Species 253 260 E. coli
N4 Reference T4 Taxonomy:562
T5 Species 337 341 EHEC
N5 Reference T5 Taxonomy:562
T6 Species 572 577 human
N6 Reference T6 Taxonomy:9606
T7 Species 619 637 EHEC O157:H7 Sakai
N7 Reference T7 Taxonomy:562
T8 Species 864 876 EHEC O157:H7
N8 Reference T8 Taxonomy:562
T9 Species 1613 1620 E. coli
N9 Reference T9 Taxonomy:562
T10 Species 1702 1709 O157:H7
N10 Reference T10 Taxonomy:562