LpxT is an inner membrane protein that transfers a phosphate group from the essential lipid undecaprenyl pyrophosphate (C-55PP) to the lipid A moiety of lipopolysaccharide, generating a lipid A tris-phosphorylated species. The protein is encoded by the non-essential lpxT gene, which is conserved in distantly related Gram-negative bacteria. In this work, we investigated the phenotypic effect of lpxT ectopic expression from a plasmid in Escherichia coli. We found that lpxT induction inhibited cell division and led to the formation of elongated cells, mostly with absent or altered septa. Moreover, the cells became sensitive to detergents and to hypo-osmotic shock, indicating that they had cell envelope defects. These effects were not due to lipid A hyperphosphorylation or C-55PP sequestering, but most likely to defective lipopolysaccharide transport. Indeed, lpxT overexpression in mutants lacking the L,D-transpeptidase LdtD and LdtE, which protect cells with outer membrane defects from osmotic lysis, caused cell envelope defects. Moreover, we found that pyrophosphorylated lipid A was also produced in a lpxT deletion mutant, indicating that LpxT is not the only protein able to perform such lipid A modification in E. coli.
Overexpression of lpxT Gene in Escherichia coli Inhibits Cell Division and Causes Envelope Defects without Changing the Overall Phosphorylation Level of Lipid A / F. Falchi, F. Di Lorenzo, R. Pizzoccheri, G. Casino, M. Paroni, F. Forti, A. Molinaro, F. Briani. - In: MICROORGANISMS. - ISSN 2076-2607. - 8:6(2020 May 30).
|Titolo:||Overexpression of lpxT Gene in Escherichia coli Inhibits Cell Division and Causes Envelope Defects without Changing the Overall Phosphorylation Level of Lipid A|
FALCHI, FEDERICA ANNA (Primo)
BRIANI, FEDERICA (Ultimo) (Corresponding)
|Parole Chiave:||L,D-transpeptidases; LPS transport; LpxT; lipid A modification; lipid A phosphorylation; lipopolysaccharide (LPS); membrane proteins; outer membrane; peptidoglycan;|
|Settore Scientifico Disciplinare:||Settore BIO/19 - Microbiologia Generale|
Settore BIO/18 - Genetica
|Data di pubblicazione:||30-mag-2020|
|Digital Object Identifier (DOI):||http://dx.doi.org/10.3390/microorganisms8060826|
|Appare nelle tipologie:||01 - Articolo su periodico|