Asher King

Asher King

@subtisilly.bsky.social

Bacillus subtilis fanatic / PhD candidate in the Eswara Lab at USF ☀️

14 followers13 following12 posts

Asher King reposted

Lily McKnight
@lilymcknight.bsky.social

1/10 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...

Asher King reposted

STCmicrobeblog
@stcmicrobeblog.bsky.social

the "Mg²⁺ problem" has been known for a long time. For example, in the standard "rich medium" LB (see👇). now we get to know more about the reasons! #MicroSky

smallthingsconsidered.blogThe Lim­i­ta­tions of LB Mediumby Hiroshi Nikaido — LB medium, also known incorrectly as Luria-Bertani medium, is widely used to grow bacterial cultures, mainly because it is easy to prepare and provides a broad base of nutrien…
Kumaran Ramamurthi@ramamurthilab.bsky.social

Folks have known for years that adding magnesium to media rescues the lethality of deleting many 'essential' genes, but why? @eswaralab.bsky.social and @subtisilly.bsky.social say that free iron builds up in these mutants. Mg2+ mitigates this by redirecting metabolism towards limiting ROS production

Asher King reposted

Kumaran Ramamurthi
@ramamurthilab.bsky.social

Folks have known for years that adding magnesium to media rescues the lethality of deleting many 'essential' genes, but why? @eswaralab.bsky.social and @subtisilly.bsky.social say that free iron builds up in these mutants. Mg2+ mitigates this by redirecting metabolism towards limiting ROS production

Asher King@subtisilly.bsky.social

I 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... #MicroSky

biorxiv.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...

Asher King reposted

Prahathees Eswara
@eswaralab.bsky.social

Thrilled to share this insightful work of Asher King @subtisilly.bsky.social and Pilar Horigian @pilarhorigian.bsky.social! #ProudPI #MicroSky #AMR #SubtiWiki In this work, we reveal the *magic* behind the protective effects of magnesium in Bacillus subtilis. Read Asher's 🧵 below for more details.

Asher King@subtisilly.bsky.social

I 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... #MicroSky

biorxiv.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...
Asher King
@subtisilly.bsky.social

8/9 Together our results exposed, at least some aspects of, the magic behind the effects of magnesium and highlight the importance of cell envelope biogenesis on metal homeostasis. Our data also showed that antibiotic killing can be modulated through electron transport function and labile iron pools

Asher King
@subtisilly.bsky.social

6/9 We also observed that Mg (and glucose) reduces the strength of membrane potential, implying that cells may fine tune energy generation pathways differentially in the presence of magnesium.

Asher King
@subtisilly.bsky.social

7/9 Finally: does blocking cell wall synthesis with beta-lactams phenocopy our genetics? Yes!! Mg addition let otherwise WT cells grow in cefepime. Pushing cells toward fermentation, by limiting ETC function or promoting overflow metabolism, also protected them from cefepime killing.

Asher King
@subtisilly.bsky.social

4/9 Mg supplementation appears to activate ROS response systems and shrink the labile iron pool, which we think is what lets certain cell wall mutants grow. ROS from the electron transport chain, specifically the terminal quinol oxidase QoxABCD, is the main driver of Fe/Mn toxicity in Del-ezrA cells

Asher King
@subtisilly.bsky.social

5/9 Additionally, we demonstrated that promoting overflow metabolism by glucose addition OR restricting ETC function through the deletion of qoxABCD genes, allow cells to circumvent Fe/Mn intoxication (amplifies ROS production or impairs oxidative stress response).

Asher King
@subtisilly.bsky.social

2/9 The cell envelope is our forte in the Eswara lab (@eswaralab.bsky.social), so we tackled this 50-year-old mystery with our favorite proteins, EzrA and GpsB. Cells lacking both are synthetically sick and rescued by magnesium. We used that growth defect to better understand the Mg effect.

Asher King
@subtisilly.bsky.social

3/9 Using genetics and biochemistry, we found the ezrA gpsB double mutant accumulates high levels of intracellular iron, fails to activate traditional ROS response systems, and produces elevated ROS. Similar but milder phenotypes appear in cells lacking EzrA alone or the class A PBP, PBP1.

Asher King
@subtisilly.bsky.social

1/9 The enigmatic protective effects of magnesium have been known in the B. subtilis field for nearly 50 years. Adding large amounts of Mg to the growth medium allows the deletion of otherwise essential genes. Curiously, nearly all of these genes are involved in cell envelope biogenesis.

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