GO_REF:0000002

Gene Ontology annotation through association of InterPro records with GO terms

InterPro domains IPR001570, IPR013856, IPR023612 identify Peptidase_M4 family membership

GO_REF:0000033

Annotation inferences using phylogenetic trees

Phylogenetic relationship to thermolysin (P14756) supports proteolysis annotation

GO_REF:0000043

Gene Ontology annotation based on UniProtKB/Swiss-Prot keyword mapping

Keywords Protease, Metalloprotease, Hydrolase, Metal-binding map to corresponding GO terms

GO_REF:0000044

Gene Ontology annotation based on UniProtKB/Swiss-Prot Subcellular Location vocabulary mapping

GO_REF:0000120

Combined Automated Annotation using Multiple IEA Methods

UniProt:P68736

UniProt entry for Bacillus subtilis bacillolysin (NprE)

Extracellular zinc metalloprotease with thermolysin-like activity

"FUNCTION: Extracellular zinc metalloprotease"
Binds calcium ions for structural stability

"Binds 4 Ca(2+) ions per subunit"
Binds zinc for catalytic activity

"Binds 1 zinc ion per subunit"
Secreted protein

"SUBCELLULAR LOCATION: Secreted"
Member of peptidase M4 family

"Belongs to the peptidase M4 family"

file:BACSU/nprE/nprE-deep-research-falcon.md

Deep research review of nprE gene function

NprE is one of two dominant extracellular proteases in B. subtilis stationary phase

"NprE is a secreted zinc metallopeptidase of the peptidase M4 family (thermolysin-like proteases) and is one of the two dominant extracellular proteases in stationary phase culture supernatants (the other is AprE/subtilisin)"
M4 family proteases contain HExxH zinc-binding motif and use Glu-zincin mechanism

"Thermolysin-like M4 metalloproteases are "Glu-zincins," using the conserved HExxH motif to bind Zn2+ (His-His) and a downstream Glu as the third zinc ligand; catalysis proceeds via activation of a zinc-bound water/hydroxide for peptide bond hydrolysis"
Deletion of nprE and aprE reduces extracellular protease activity by approximately 95%

"Deletion of nprE and aprE together reduces culture supernatant protease activity by ~95% in stationary phase"
NprE is secreted and accumulates extracellularly

"Mature NprE is extracellular/secreted, accumulating in stationary-phase culture supernatants"
Activity abolished by chelators, enhanced by Ca2+

"Activity is abolished by chelators (e.g., EDTA), and Ca2+ enhances stability/activity"
Ca2+ provides structural stability

"Ca2+ ions stabilize structure and thermal resistance"
Expression regulated by CodY, ScoC, AbrB, and DegU~P

"nprE expression is strongly expressed only post-exponentially/late log-to-stationary phase. Regulation involves: (i) direct repression by CodY under nutrient-replete conditions"