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Multimers of the precursor of a type IV pilin‐like component of the general secretory pathway are unrelated to pili
Author(s) -
Pugsley Anthony P.
Publication year - 1996
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/j.1365-2958.1996.tb02643.x
Subject(s) - pilin , pilus , biology , cytoplasm , signal peptide , proteolysis , bacterial outer membrane , biochemistry , signal peptidase , peptide sequence , microbiology and biotechnology , enzyme , gene , escherichia coli
Summary Both the mature and precursor forms of PulG, a type IV pilin‐like component of the general secretory pathway of Klebsiella oxytoca , can be chemically cross‐linked into multimers similar to those obtained by cross‐linking the components of type IV pili. To explore the possibility that the PulG precursor could form a pilus‐like structure, the PulG sequence was altered in a variety of ways, including (i) replacement of the characteristic hydrophobic region, which is required for the assembly of type IV pilins by the MalE signal peptide, or (ii) fusion of β‐lactamase (βlaM) to the C‐terminus. Neither of these changes affected multimerization. PulG precursor could be post‐translationally processed by pre‐pilin peptidase (PulO), indicating that the N‐terminus of pre PulG remains on the cytoplasmic side of the cytoplasmic membrane where it is accessible to the catalytic site of this enzyme. Finally, precursor and mature forms of PulG could be efficiently cross‐linked in a mixed dimer, indicating that at least a subpopu‐lation of the two forms of the protein are probably located in clusters in the cytoplasmic membrane. These results provide further evidence that the cross‐linked multimers of the precursor form of PulG are unrelated to type IV pilus‐like structures. It is still unclear whether a subpopulation of processed PulG can be assembled into a rudimentary pilus‐like structure.