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Borrelia burgdorferi lipoproteins are secreted to the outer surface by default
Author(s) -
Schulze Ryan J.,
Zückert Wolfram R.
Publication year - 2006
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.1365-2958.2006.05039.x
Subject(s) - periplasmic space , borrelia burgdorferi , biology , bacterial outer membrane , signal peptide , lipoprotein , secretion , microbiology and biotechnology , biochemistry , borrelia , bacteria , peptide sequence , gene , escherichia coli , genetics , antibody , cholesterol
Summary Borrelia spirochaetes are unique among diderm bacteria in their abundance of surface‐displayed lipoproteins, some of which play important roles in the pathogenesis of Lyme disease and relapsing fever. To identify the lipoprotein‐sorting signals in Borrelia burgdorferi , we generated chimeras between the outer surface lipoprotein OspA, the periplasmic oligopeptide‐binding lipoprotein OppAIV and mRFP1, a monomeric red fluorescent reporter protein. Localization of OspA and OppAIV point mutants showed that Borrelia lipoproteins do not follow the ‘+2’ sorting rule which targets lipoproteins to the cytoplasmic or outer membrane of Gram‐negative bacteria via the Lol pathway. Fusions of mRFP1 to short N‐terminal lipopeptides of OspA, and surprisingly OppAIV, were targeted to the spirochaetal surface. Mutagenesis of the OspA N‐terminus defined less than five N‐terminal amino acids as the minimal secretion‐facilitating signal. With the exception of negative charges, which can act as partial subsurface retention signals in certain peptide contexts, lipoprotein secretion occurs independent of N‐terminal sequence. Together, these data indicate that Borrelia lipoproteins are targeted to the bacterial surface by default, but can be retained in the periplasm by sequence‐specific signals.