Lily McKnight @lilymcknight.bsky.social · 1m10/10 SO proud of this work from @eswaralab.bsky.social and extremely grateful for my awesome team: Olivia Payne, @subtisilly.bsky.social, Jason Carroll, Briana Boyer, Andrew Brown, and Lauren Hammond 🤗 000
Lily McKnight @lilymcknight.bsky.social · 5m9/10 So, we propose GpsB acts as a peptidoglycan supply-chain sentinel: it watches cell wall synthesis through PBP2 (and PBP4, PBP2a, etc.), amplifies stress signaling through Stk1 and VraSR, and keeps MurA and MurZ protected on an as-needed basis.💪 100
Lily McKnight @lilymcknight.bsky.social · 5m8/10 And we find that GpsB interacts directly with VraR, and with histidine kinase VraS exclusively in the phosphomimetic state. As far as we know, this is the first direct link between GpsB and a two-component system. ΔvraR ΔgpsB and ΔvraS ΔgpsB are hypersensitive to fosfomycin.😱 100
Lily McKnight @lilymcknight.bsky.social · 6m7/10 murZ is transcriptionally regulated by VraRS under cell wall stress. A PmurZ-lux reporter shows murZ upregulation is badly impaired in ΔgpsB, even without antibiotic. That pointed us straight at VraRS.🫣 100
Lily McKnight @lilymcknight.bsky.social · 6m6/10 Fosfomycin targets MurA and MurZ (first committed step of PG synthesis). We find GpsB interacts directly with MurA, ReoM, and ReoY (MurA turnover machinery) but not MurZ (which indirectly interacts with GpsB via ReoM). Deleting reoY, which stabilizes MurA, reverses ΔgpsB fosfomycin sensitivity. 100
Lily McKnight @lilymcknight.bsky.social · 7m5/10 Since Stk1 is tied to drug resistance, we tested ΔgpsB against fosfomycin pressure. ΔgpsB is far more sensitive than Δstk1, and the double mutant barely survives. Complementation only works with phospho-tunable GpsB, as locking it in an “on” (T75E) state doesn’t lead to full rescue.🔄 100
Lily McKnight @lilymcknight.bsky.social · 8m4/10 Phosphorylation of GpsB does not impact self-interaction, but it does alter partner preference. T75E associates strongly with Ser/Thr kinase Stk1, yet much weaker with PBP2 and FtsZ. We also identified a brand-new partner in the process: PBP2a (MRSA)!😋 100
Lily McKnight @lilymcknight.bsky.social · 8m3/10 Upon point mutagenesis, we found 3/6 were physiologically relevant: T21, T75, and S76. Phosphomimetic substitution of just one of these three sites is enough to abolish GpsB overproduction toxicity. But why does this matter?🤔 100
Lily McKnight @lilymcknight.bsky.social · 9m2/10 It is known that GpsB facilitates cell division and cell wall synthesis through protein-protein interactions. But how does it prioritize them? Phosphoproteomics identified six Ser/Thr phosphosites on S. aureus GpsB, four in its IDR, hinting these could tune its interactions... 100
Lily McKnight @lilymcknight.bsky.social · 9m1/10 I am thrilled to announce my first first-author preprint, now live on bioRxiv! This focuses on my favorite little protein, GpsB, and its ties to fosfomycin resistance through phosphoregulation in S. aureus (a 🧵) www.biorxiv.org/content/10.6...biorxiv.orgStaphylococcus aureus GpsB, Stk, and VraSR form a cell wall surveillance network to maintain cell envelope integrity and mediate antibiotic resistanceAntibiotic resistance is an alarming threat to public health worldwide. Specifically, drug-resistant Staphylococcus aureus remains a major contributor to global mortality. Therefore, in-depth understa... 100
Reposted by Lily McKnightAsher King @subtisilly.bsky.social · 02/09/2026I am so excited to share my first first-author manuscript regarding the mysterious effects of magnesium in Bacillus subtilis! 🧵⬇️ www.biorxiv.org/content/10.6... #MicroSkybiorxiv.orgMagnesium induces iron starvation and metabolic rewiring to support the viability of cell envelope mutants and antibiotic-stressed cellsMagnesium supplementation permits deletion of otherwise essential genes involved in cell envelope biogenesis in the Gram-positive model bacterium Bacillus subtilis. Yet, the specific underlying mechan... 3238
