Comparative phylogenomics of bacterial urease systems reveals architectural conservation, lineage-specific...

Urease is a nickel-dependent, multi-gene bacterial system that contributes to nitrogen acquisition, pH homeostasis, and ecological adaptation, yet most comparative studies rely on single-gene markers such as ureC. Here, we analyzed 237 complete genomes from a stratified bacterial panel integrating ecological and genome-level metadata, annotation-guided screening, profile-HMM detection, locus reconstruction, and species-tree comparison. Within this panel, 149 genomes encoded at least one complete urease locus, 11 contained candidate but incomplete neighborhoods, and 77 lacked any supported urease locus. At the locus level, we recovered 173 urease-associated neighborhoods, including 150 canonical ureABC loci, 7 Helicobacter AB fusion loci, and 16 partial or split loci. The canonical three-subunit architecture therefore dominated the dataset, whereas the Helicobacter-type configuration persisted as a small but stable lineage-restricted alternative. Eight genomes encoded duplicated complete canonical systems, and in each case, both loci mapped to the same top-level assembly sequence record. Their paired loci differed in gene order and typically shared only about 62-63% concatenated ureABC identity, consistent with older divergence or secondary acquisition rather than recent exact duplication. Comparison of the concatenated ureABC gene tree with the species tree identified 12 candidate incongruent loci, all involving complete canonical systems. A manual review of the strongest examples highlighted ecologically coherent modules in nitrifiers and marine cyanobacteria, as well as nickel- and hydrogenase-associated urease neighborhoods in enteric bacteria. Together, these results establish bacterial urease as a broadly conserved but evolutionarily flexible genomic component shaped by architectural conservation, lineage-specific specialization, duplication, and occasional intergeneric transfer.