Biophysical Characterization and Structural Insights Into the Complex between the Extracytoplasmic Function Sigma Factor, PupI, with the Antisigma Domain of the Sigma Regulator, PupR, from <i>Pseudomonas capeferrum</i>.

ABSTRACT: Gram-negative bacteria utilize siderophores to scavenge for environmental iron. Pseudomonas capeferrum produces the siderophores pseudobactin BN7/8, which trigger cell surface signaling (CSS). Iron import CSS pathways consist of an outer membrane TonB-dependent transporter, an inner membrane sigma regulator, and a cytoplasmic sigma factor that activates transcription of target genes. The P. capeferrum sigma regulator, PupR, has an N-terminal antisigma domain (ASD). Previously, the PupR ASD was purified as a dimer in the absence of its cognate sigma factor, PupI. Here we use pulldown assays to demonstrate that His₆-PupI^FL interacts with the PupR ASD as well as with homodimer-disrupting mutants. We show that the PupR ASD and PupI bind with a dissociation c

SUBMITTER: Sultana T 

PROVIDER: S-EPMC12809585 | biostudies-literature | 2026 Jan

REPOSITORIES: biostudies-literature