Imperial College London


Faculty of Natural SciencesDepartment of Life Sciences

Lecturer in Molecular Microbiology



+44 (0)20 7594 7463g.larrouy-maumus




3.42Flowers buildingSouth Kensington Campus






BibTex format

author = {Robert, CB and Thomson, M and Vercellone, A and Gardner, F and Ernst, RK and Larrouy-Maumus, G and Nigou, J},
doi = {10.1016/j.biochi.2017.08.008},
journal = {Biochimie},
pages = {16--20},
title = {Mass spectrometry analysis of intact Francisella bacteria identifies lipid A structure remodeling in response to acidic pH stress.},
url = {},
volume = {141},
year = {2017}

RIS format (EndNote, RefMan)

AB - Structural modification of lipid A, the lipid anchor of LPS, is one of the strategies used by Gram-negative bacteria to evade host innate immunity. Francisella tularensis is a human pathogen that infects and replicates within phagocytic cells. It produces an atypical lipid A, whose structure precludes an efficient recognition by both innate immune players, TLR4 and cationic antimicrobial peptides. Interestingly, a recent report indicates that the lipid A of Francisella (LVS vaccinal strain) undergoes polar modifications when bacteria are grown in human macrophages as compared to in broth. To characterize the structural modifications of lipid A that may be induced intracellularly, Francisella novicida, a surrogate strain for the highly virulent F. tularensis, was submitted to different stress conditions mimicking the harsh environment encountered in the macrophages. To analyze lipid A directly from intact bacteria without any chemical treatment or purification steps, we used a rapid and sensitive MALDI-TOF mass spectrometry approach. Among the many conditions tested, only bacteria exposure to acidic pHs (from 6 to 5) induced a change in lipid A structure. These changes were characterized by an increase in the relative abundance of molecular species bearing an additional hexose unit on the diglucosamine backbone, similar to species present when bacteria are grown under reduced environmental temperature. This lipid A glyco-form, which is observed in trace amounts in normal in vitro growth conditions at 37 °C, may contribute to the intracellular parasitism of macrophages by Francisella.
AU - Robert,CB
AU - Thomson,M
AU - Vercellone,A
AU - Gardner,F
AU - Ernst,RK
AU - Larrouy-Maumus,G
AU - Nigou,J
DO - 10.1016/j.biochi.2017.08.008
EP - 20
PY - 2017///
SP - 16
TI - Mass spectrometry analysis of intact Francisella bacteria identifies lipid A structure remodeling in response to acidic pH stress.
T2 - Biochimie
UR -
UR -
VL - 141
ER -