Journal article
Urease-Encoding Genes in Ammonia-Oxidizing Bacteria
Applied and environmental microbiology, Vol.70(4), pp.2342-2348
04/2004
Handle:
https://hdl.handle.net/2376/108631
PMCID: PMC383159
PMID: 15066830
Abstract
Many but not all ammonia-oxidizing bacteria (AOB) produce urease (urea amidohydrolase, EC 3.5.1.5) and are capable of using urea for chemolithotrophic growth. We sequenced the urease operons from two AOB, the β-proteobacterium
Nitrosospira
sp. strain NpAV and the γ-proteobacterium
Nitrosococcus oceani
. In both organisms, all seven urease genes were contiguous: the three structural urease genes
ureABC
were preceded and succeeded by the accessory genes
ureD
and
ureEFG
, respectively. Green fluorescent protein reporter gene fusions revealed that the
ure
genes were under control of a single operon promoter upstream of the
ureD
gene in
Nitrosococcus oceani
. Southern analyses revealed two copies of
ureC
in the
Nitrosospira
sp. strain NpAV genome, while a single copy of the
ure
operon was detected in the genome of
Nitrosococcus oceani.
The
ureC
gene encodes the alpha subunit protein containing the active site and conserved nickel binding ligands; these conserved regions were suitable primer targets for obtaining further
ureC
sequences from additional AOB. In order to develop molecular tools for detecting the ureolytic ecotype of AOB,
ureC
genes were sequenced from several β-proteobacterial AOB. Pairwise identity values ranged from 80 to 90% for the UreC peptides of AOB within a subdivision. UreC sequences deduced from AOB urease genes and available UreC sequences in the public databases were used to construct alignments and make phylogenetic inferences. The UreC proteins from β-proteobacterial AOB formed a distinct monophyletic group. Unexpectedly, the peptides from AOB did not group most closely with the UreC proteins from other β-proteobacteria. Instead, it appears that urease in β-proteobacterial autotrophic ammonia oxidizers is the product of divergent evolution in the common ancestor of γ- and β-proteobacteria that was initiated before their divergence during speciation. Sequence motifs conserved for the proteobacteria and variable regions possibly discriminatory for
ureC
from β-proteobacterial AOB were identified for future use in environmental analysis of ureolytic AOB. These gene sequences are the first publicly available for
ure
genes from autotrophic AOB.
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Details
- Title
- Urease-Encoding Genes in Ammonia-Oxidizing Bacteria
- Creators
- Teresa E Koper - Departments of BiologyAmal F El-Sheikh - Departments of BiologyJeanette M Norton - Departments of BiologyMartin G Klotz - Departments of Biology
- Publication Details
- Applied and environmental microbiology, Vol.70(4), pp.2342-2348
- Academic Unit
- Molecular Biosciences, School of
- Publisher
- American Society for Microbiology
- Identifiers
- 99900547484801842
- Language
- English
- Resource Type
- Journal article