The lipopolysaccharide (LPS) transport (Lpt) system is responsible for transferring LPS from the periplasmic surface of the inner membrane (IM) to the outer leaflet of the outer membrane (OM), where it plays a crucial role in OMselective permeability. In E. coli seven essential proteins are assembled in an Lpt trans-envelope complex, which is conserved in γ-Proteobacteria. LptBFG constitute the IMABC transporter, LptDE form the OM translocon for final LPS delivery, whereas LptC, an IM-anchored protein with a periplasmic domain, interacts with the IM ABC transporter, the periplasmic protein LptA, and LPS. Although essential, LptC can tolerate several mutations and its role in LPS transport is unclear. To get insights into the functional role of LptC in the Lpt machine we searched for viable mutants lacking LptC by applying a strong double selection for lptC deletion mutants. Genome sequencing of viable ΔlptC mutants revealed single amino acid substitutions at a unique position in the predicted large periplasmic domain of the IM component LptF (LptFSupC). In complementation tests, lptFSupC mutants suppress lethality of both ΔlptC and lptC conditional expressionmutants. Our data show that mutations in a specific residue of the predicted LptF periplasmic domain can compensate the lack of the essential protein LptC, implicate such LptF domain in the formation of the periplasmic bridge between the IM and OMcomplexes, and suggest that LptC may have evolved to improve the performance of an ancestral six-component Lpt machine.
The lack of the essential LptC protein in the trans-envelope lipopolysaccharide transport machine is circumvented by suppressor mutations in LptF, an inner membrane component of the Escherichia coli transporter / M. Benedet, F.A. Falchi, S. Puccio, C. Di Benedetto, C. Peano, A. Polissi, G. Dehò. - In: PLOS ONE. - ISSN 1932-6203. - 11:8(2016 Aug), pp. e0161354.1-e0161354.21.
|Titolo:||The lack of the essential LptC protein in the trans-envelope lipopolysaccharide transport machine is circumvented by suppressor mutations in LptF, an inner membrane component of the Escherichia coli transporter|
|Parole Chiave:||Agricultural and Biological Sciences (all); Biochemistry, Genetics and Molecular Biology (all); Medicine (all)|
|Settore Scientifico Disciplinare:||Settore BIO/19 - Microbiologia Generale|
|Progetto:||Nuovi antibiotici mediante rational design|
|Data di pubblicazione:||ago-2016|
|Digital Object Identifier (DOI):||http://dx.doi.org/10.1371/journal.pone.0161354|
|Appare nelle tipologie:||01 - Articolo su periodico|
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