Structure and mechanism of action of Sda, an inhibitor of the histidine kinases that regulate initiation of sporulation in Bacillus subtilis.
Histidine kinases are used extensively in prokaryotes to monitor and respond to changes in cellular and environmental conditions. In Bacillus subtilis, sporulation-specific gene expression is controlled by a histidine kinase phosphorelay that culminates in phosphorylation of the Spo0A transcription factor. Sda provides a developmental checkpoint by inhibiting this phosphorelay in response to DNA damage and replication defects. We show that Sda acts at the first step in the relay by inhibiting autophosphorylation of the histidine kinase KinA. The structure of Sda, which we determined using NMR, comprises a helical hairpin. A cluster of conserved residues on one face of the hairpin mediates an interaction between Sda and the KinA dimerization/phosphotransfer domain. This interaction stabilizes the KinA dimer, and the two proteins form a stable heterotetramer. The data indicate that Sda forms a molecular barricade that inhibits productive interaction between the catalytic and phosphotransfer domains of KinA.
Rowland
Susan L
SL
Department of Molecular, Microbial and Structural Biology, University of Connecticut Health Center, 263 Farmington Avenue, Farmington, CT 06030 USA.
Burkholder
William F
WF
Cunningham
Katherine A
KA
Maciejewski
Mark W
MW
Grossman
Alan D
AD
King
Glenn F
GF
D000595:Amino Acid Sequence / Q000235:genetics; D001412:Bacillus subtilis / Q000201:enzymology* / Q000235:genetics; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D001665:Binding Sites / Q000235:genetics; D018797:Cell Cycle Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D019281:Dimerization; D015964:Gene Expression Regulation, Bacterial / Q000235:genetics; D015971:Gene Expression Regulation, Enzymologic / Q000235:genetics; D000071677:Histidine Kinase; D008958:Models, Molecular; D008969:Molecular Sequence Data; D010766:Phosphorylation; D011485:Protein Binding / Q000235:genetics; D047428:Protein Kinase Inhibitors; D011494:Protein Kinases / Q000235:genetics / Q000378:metabolism*; D017433:Protein Structure, Secondary / Q000235:genetics; D017434:Protein Structure, Tertiary / Q000502:physiology; D013171:Spores, Bacterial / Q000201:enzymology* / Q000235:genetics; D014157:Transcription Factors / Q000378:metabolism
D001426:Bacterial Proteins; D018797:Cell Cycle Proteins; D004268:DNA-Binding Proteins; D047428:Protein Kinase Inhibitors; C080950:Spo0A protein, Bacillus subtilis; D014157:Transcription Factors; C075521:kinA protein, Bacillus subtilis; C422745:suppressor of DnaA, Bacillus subtilis; D011494:Protein Kinases; D000071677:Histidine Kinase