title: Substrate specificity of SpoIIGA, a signal-transducing aspartic protease in Bacilli.
abstract: SpoIIGA is a novel type of membrane-associated aspartic protease that responds to a signal from the forespore by cleaving Pro-σ(E) in the mother cell during sporulation of Bacillus subtilis. Very little is known about how SpoIIGA recognizes Pro-σ(E). By co-expressing proteins in Escherichia coli, it was shown that charge reversal substitutions for acidic residues 24 and 25 of Pro-σ(E), and for basic residues 245 and 284 of SpoIIGA, impaired cleavage. These results are consistent with a model predicting possible electrostatic interactions between these residues; however, no charge reversal substitution for residue 245 or residue 284 of SpoIIGA restored cleavage of Pro-σ(E) with a charge reversal substitution for residue 24 or residue 25. Bacillus subtilis SpoIIGA cleaved Pro-σ(E) orthologs from Bacillus licheniformis and Bacillus halodurans, but not from Bacillus cereus. A triple substitution in the pro-sequence of B. cereus Pro-σ(E) allowed cleavage by B. subtilis SpoIIGA, indicating that residues distal from the cleavage site contribute to substrate specificity. Co-expression of SpoIIGA and Pro-σ(E) orthologs in different combinations suggested that B. licheniformis SpoIIGA has a relatively narrow substrate specificity as compared with B. subtilis SpoIIGA, whereas B. cereus SpoIIGA and B. halodurans SpoIIGA appear to have broader substrate specificity.
authors.affiliation: Faculty of Pharmaceutical Sciences, Setsunan University, Osaka, Japan.
authors.forename: Daisuke
authors.initials: D
authors.lastname: Imamura
authors.forename: Ritsuko
authors.initials: R
authors.lastname: Kuwana
authors.forename: Lee
authors.initials: L
authors.lastname: Kroos
authors.forename: Michael
authors.initials: M
authors.lastname: Feig
authors.forename: Hiromu
authors.initials: H
authors.lastname: Takamatsu
authors.forename: Kazuhito
authors.initials: K
authors.lastname: Watabe
mesh_terms: D001412:Bacillus subtilis / Q000201:enzymology*; D001426:Bacterial Proteins / Q000737:chemistry / Q000378:metabolism*; D008565:Membrane Proteins / Q000737:chemistry / Q000378:metabolism*; D010447:Peptide Hydrolases / Q000737:chemistry / Q000378:metabolism*; D015398:Signal Transduction; D013379:Substrate Specificity
chemical_list: D001426:Bacterial Proteins; D008565:Membrane Proteins; D010447:Peptide Hydrolases; C071976:SpoIIGA protein, Bacillus subtilis