Biology subjects

Fullam, E.

Publications and source records attributed to Fullam, E..

4 recordsLinked to original sources

bioRxiv2024

Fluorinated trehalose analogues for cell surface engineering and imaging of Mycobacterium tuberculosis

The sensitive, rapid and accurate diagnosis of Mycobacterium tuberculosis (Mtb) infection is a central challenge in controlling the global tuberculosis (TB) pandemic. Yet the detection of mycobacteria is often made difficult by the low sensitivity of current diagnostic tools, with over 3.6 million TB cases missed each year. To overcome these limitations there is an urgent need for next-generation TB diagnostic technologies. Here we report the use of a discrete panel of native 19F-trehalose (F-Tre) analogues to label and directly visualise Mtb by exploiting the uptake of fluorine-modified trehalose analogues via the mycobacterial trehalose LpqY-SugABC ATP-binding cassette (ABC) importer. We discovered the extent of modified F-Tre uptake correlates with LpqY substrate recognition and characterisation of the interacting sites by saturation transfer difference NMR coupled with molecular dynamics provides a unique glimpse into the molecular basis of fluorine-modified trehalose import in Mtb. Lipid profiling demonstrated that F-Tre analogues modified at positions 2, 3 and 6 are incorporated into mycobacterial cell-surface trehalose-containing glycolipids. This rapid one-step labelling approach facilitates the direct visualisation of F-Tre-labelled Mtb by focused ion beam (FIB) secondary ion mass spectrometry (SIMS), enabling pathogen specific detection. Collectively, our findings highlight that F-Tre analogues have potential as tools to probe and unravel Mtb biology and can be exploited to detect and image TB.

microbiology↗

bioRxiv2022

From Molecular Dynamics to Supramolecular Organization: The Role of PIM Lipids in the Originality of the Mycobacterial Plasma Membrane

Mycobacterium tuberculosis (Mtb) is the causative agent of tuberculosis, a disease that claims ~1.5 million lives annually. The current treatment regime is long and expensive, and missed doses contribute to drug resistance. There is much to be understood about the Mtb cell envelope, a complicated barrier that antibiotics need to negotiate to enter the cell. Within this envelope, the plasma membrane is the ultimate obstacle and is proposed to be comprised of over 50% mannosylated phosphatidylinositol lipids (phosphatidyl-myoinositol mannosides, PIMs), whose role in the membrane structure remains elusive. Here we used multiscale molecular dynamics (MD) simulations to understand the structure-function relationship of the PIM lipid family and decipher how they self-organize to drive biophysical properties of the Mycobacterial plasma membrane. To validate the model, we tested known anti-tubercular drugs and replicated previous experimental results. Our results shed new light into the organization of the Mycobacterial plasma membrane and provides a working model of this complex membrane to use for in silico studies. This opens the door for new methods to probe potential antibiotic targets and further understand membrane protein function. O_FIG O_LINKSMALLFIG WIDTH=169 HEIGHT=200 SRC="FIGDIR/small/498153v1_ufig1.gif" ALT="Figure 1"> View larger version (56K): org.highwire.dtl.DTLVardef@102b357org.highwire.dtl.DTLVardef@4c30f8org.highwire.dtl.DTLVardef@22f32aorg.highwire.dtl.DTLVardef@8a6f65_HPS_FORMAT_FIGEXP M_FIG C_FIG

biophysics↗

bioRxiv2019

Structural basis of glycerophosphodiester recognition by the Mycobacterium tuberculosis substrate-binding protein UgpB

Mycobacterium tuberculosis (Mtb) is the causative agent of tuberculosis (TB) and has evolved an incredible ability to survive latently within the human host for decades. The Mtb pathogen encodes for a low number of ATP-binding cassette (ABC) importers for the acquisition of carbohydrates that may reflect the nutrient poor environment within the host macrophages. Mtb UgpB (Rv2833) is the substrate binding domain of the UgpABCE transporter that recognises glycerophosphocholine (GPC) indicating a potential role in glycerophospholipid recycling. By using a combination of saturation transfer difference (STD) NMR and X-ray crystallography we report the structural analysis of Mtb UgpB complexed with GPC and have identified that Mtb UgpB is promiscuous for other glycerophosphodiesters. Complementary biochemical analyses and site-directed mutagenesis define the molecular basis and specificity of glycerophosphodiester recognition. Our results provide critical insights into the structural and functional role of the Mtb UgpB transporter and reveal that the specificity of this ABC-transporter is not limited to GPC therefore optimising the ability of Mtb to scavenge scarce nutrients and essential glycerophospholipid metabolites during intracellular infection.

biochemistry↗

bioRxiv2019

Targeting extracellular glycans: Tuning multimeric boronic acids for pathogen-selective killing of Mycobacterium tuberculosis

Innovative chemotherapeutic agents that are active against Mycobacterium tuberculosis (Mtb) are urgently required to control the tuberculosis (TB) epidemic. The Mtb cell envelope has distinct (lipo)polysaccharides and glycolipids that play a critical role in Mtb survival and pathogenesis and disruption of pathways involved in the assembly of the Mtb cell envelope are the primary target of anti-tubercular agents. Here we introduce a previously unexplored approach whereby chemical agents directly target the extracellular glycans within the unique Mtb cell envelope, rather than the intracellular biosynthetic machinery. We designed and synthesised multimeric boronic acids that are selectivity lethal to Mtb and function by targeting these structurally unique and essential Mtb cell envelope glycans. By tuning the number of, and distance between, boronic acid units high selectivity to Mtb, low cytotoxicity against mammalian cells and no observable resistance was achieved. This non-conventional approach may prevent the development of drug-resistance and will act as a platform for the design of improved, pathogen-specific, next generation antibiotics.

biochemistry↗