Salmonella enterica serovar Enteritidis EN1660 proteome spectral data

H-NS is a nucleoid structuring protein and global repressor of virulence
and horizontally-acquired genes in bacteria. H-NS can interact with itself
or with homologous proteins, but protein family diversity and regulatory
network overlap remain poorly defined. Here we present a comprehensive
phylogenetic analysis that revealed deep-branching clades, dispelling the
presumption that H-NS is the progenitor of varied molecular backups. With
few exceptions, clades are either entirely chromosomal or entirely
plasmid-encoded proteins. On chromosomes, StpA and newly discovered HlpP
are core genes in specific genera, whereas Hfp and newly discovered HlpC
are sporadically distributed. Six clades of H-NS plasmid proteins (Hpp)
exhibit ancient and dedicated associations with plasmids, including three
clades with fidelity for plasmid incompatibility groups H, F, or X. A
proliferation of H-NS homologs in Erwiniaceae includes the first
observation of potentially co-dependent H-NS forms. Conversely, the
observed diversification of oligomerization domains may facilitate stable
co-existence of divergent homologs in a genome. Transcriptomic and
proteomic analysis of regulatory crosstalk in Salmonella revealed
networked and hierarchical control of H-NS homologs. We also discovered
that H-NS is both a repressor and activator of Salmonella Pathogenicity
Island 1 gene expression, and both modes are restored by Sfh (HppH) in the
absence of H-NS.