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The prodomain of the B ordetella two‐partner secretion pathway protein FhaB remains intracellular yet affects the conformation of the mature C ‐terminal domain
Author(s) -
Noël Christopher R.,
Mazar Joseph,
Melvin Jeffrey A.,
Sexton Jessica A.,
Cotter Peggy A.
Publication year - 2012
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1111/mmi.12036
Subject(s) - intracellular , secretion , cleavage (geology) , c terminus , biology , microbiology and biotechnology , n terminus , secretory protein , bacterial outer membrane , recombinant dna , signal peptide , biochemistry , peptide sequence , escherichia coli , amino acid , gene , paleontology , fracture (geology)
Summary Two‐partner secretion ( TPS ) systems use β‐barrel proteins of the Omp 85‐ TpsB superfamily to transport large exoproteins across the outer membranes of Gram‐negative bacteria. The Bordetella FHA / FhaC proteins are prototypical of TPS systems in which the exoprotein contains a large C ‐terminal prodomain that is removed during translocation. Although it is known that the FhaB prodomain is required for FHA function in vivo , its role in FHA maturation has remained mysterious. We show here that the FhaB prodomain is required for the extracellularly located mature C ‐terminal domain ( MCD ) of FHA to achieve its proper conformation. We show that the C ‐terminus of the prodomain is retained intracellularly and that sequences within the N ‐terminus of the prodomain are required for this intracellular localization. We also identify sequences at the C ‐terminus of the MCD that are required for release of mature FHA from the cell surface. Our data support a model in which the intracellularly located prodomain affects the final conformation of the extracellularly located MCD . We hypothesize that maturation triggers cleavage and degradation of the prodomain.