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John Helmann

@johnhelmann.bsky.social

2K followers 600 following 42 posts

Professor at Cornell Univ. Bacillus subtilis physiology and stress responses (metal homeostasis, redox stress, antibiotic resistance & cell envelope). EIC of Mol Microbiol.

Biology 55%

Environmental science 15%

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John Helmann @johnhelmann.bsky.social · 27d

For those interested in further reading, the studies establishing the triplet nature of the genetic code were also reviewed by both Benzer and Crick in two 1962 Scientific American articles -- both worth a read!
www.jstor.org/stable/24937...
www.jstor.org/stable/24936...

The Fine Structure of the Gene on JSTOR

Seymour Benzer, The Fine Structure of the Gene, Scientific American, Vol. 206, No. 1 (January 1962), pp. 70-87

Reposted by John D. Helmann

Ákos T Kovács @evolvedbiofilm.bsky.social · 27d

See our @natmicrobiol.nature.com News&Views on the publication from Yun Chen laboratory

A rapid writing exercise for María Negre Rodríguez, a PhD student in my group

Ecological function of phenazine in soil
www.nature.com/articles/s41...

#MicrobiomeEcology at #LeidenBiology

Reposted by John D. Helmann

David Lalaouna @davidlalaouna.bsky.social · Aug 24

🚨 New Preprint Alert 🚨

Our latest work, A Zur-dependent regulatory RNA involved in maintaining zinc homeostasis in Staphylococcus aureus, is now live on bioRxiv! 🧬🦠📄

Check it out here: www.biorxiv.org/content/10.1...

Reposted by John D. Helmann

Henrik Strahl @henrikstrahl.bsky.social · Aug 22

A new methods paper from us, this time with a focus on reliable monitoring membrane potential and cell lysis at different growth stages and cell densities. Also, note the surprisingly high level of background lysis in seemingly healthy B. subtilis cultures.
www.biorxiv.org/content/10.1...

Monitoring single cell bioenergetic status and cell lysis in dense and differentiating Bacillus subtilis cultures

Bacillus subtilis is a major model organism for studying population heterogeneity in clonal bacterial cultures due to its high genetic tractability and ability to differentiate into subpopulations wit...

www.biorxiv.org

Reposted by John D. Helmann

Ákos T Kovács @evolvedbiofilm.bsky.social · Aug 17

RagB stimulates the activity of the peptidoglycan polymerase RodA in Bacillus subtilis

[RagB = YrrS]

@emboreports.org by Frédérique Pompeo et al

www.embopress.org/doi/full/10....

RagB stimulates the activity of the peptidoglycan polymerase RodA in Bacillus subtilis | EMBO reports

imageimageRagB regulates the SEDS protein RodA in Bacillus subtilis, by interacting with RodA and by stimulating its activity. This regulation is essential for cell wall synthesis, especially when Cla...

www.embopress.org

Reposted by John D. Helmann

Molecular Microbiology @molmicrounihoh.bsky.social · Aug 15

A ptsH mutation (encoding the HPr-G54D variant) suppresses growth defects and antibiotic sensitivity in a Bacillus subtilis cpgA mutant defective in metabolite proofreading!

Where? In Journal of Bacteriology!

🫳 journals.asm.org/doi/10.1128/...

#subtiwiki #subtilis #CCR

A ptsH mutation suppresses growth defects and antibiotic sensitivity in a cpgA mutant defective in metabolite proofreading | Journal of Bacteriology

Metabolism relies on the concerted action of hundreds of enzymes, many of which have some activity with non-canonical substrates. The resulting reactions constitute an often-ignored underground metabolism. Glyceraldehyde-3-phosphate dehydrogenase ...

journals.asm.org

Reposted by John D. Helmann

Petra Levin @redrockcity.bsky.social · Aug 15

Elio Schaechter was one of my heroes. His 1958 paper with Ole Maaløe and Niels Kjeldgaard (fondly known as “SMK”) is a North Star for so much work in my group. A wonderful scientist, great communicator, and a very kind person. May his memory be a blessing.

Elio Schaechter and Petra in San Diego

Reposted by John D. Helmann

Romain Strock @romainstrock.bsky.social · Aug 15

This first-author publication is my… first! Archaea kill bacteria by targeting their Achilles’ heel: peptidoglycan. Big shoutout to @ahocher.bsky.social‬, @valeriesoo.bsky.social‬, Pauline Misson, @tobiaswarnecke.bsky.social‬ and MRC LMS Proteomics. A thread 🔽
journals.plos.org/plosbiology/...

Archaea produce peptidoglycan hydrolases that kill bacteria

Archaea regularly interact with bacteria but reports of archaea killing bacteria are very rare. This study shows that many archaea encode peptidoglycan hydrolases, which specifically target bacterial ...

journals.plos.org

John Helmann @johnhelmann.bsky.social · Aug 14

This paper was led by Dr. Ankita Sachla with contributions from current sr. res. assoc. Ahmed Gaballa and former undergraduate student Diana Herrera (Cornell '19; yes.... this took a while).

John Helmann @johnhelmann.bsky.social · Aug 14

The B. subtilis histidine-containing phosphocarrier protein (HPr) supports PTS-sugar import, interacts with GAPDH, and helps mediate carbon catabolite repression (CCR). Here, a mutant HPr protein is shown to alleviate metabolic intoxication in a cpgA mutant.
journals.asm.org/doi/10.1128/...

A metabolic diagram illustrating various ways the HPr protein interacts with other proteins to affect metabolism.

Reposted by John D. Helmann

Jörg Stülke @joergstuelke.bsky.social · Aug 14

New cool work from French friends and colleagues: identification of Rho termination sites in B. subtilis! academic.oup.com/nar/article/...

#SubtiWiki @narjournal.bsky.social @inrae-france.bsky.social

Comprehensive mapping of transcription terminator Rho utilization (Rut) sites across the Bacillus subtilis genome

Abstract. Recent evidence indicates that the bacterial Rho helicase regulates Bacillus subtilis gene expression in a growth-dependent manner. This regulati

academic.oup.com

John Helmann @johnhelmann.bsky.social · Jul 28

Thanks Christoph!

John Helmann @johnhelmann.bsky.social · Jul 28

Thanks Peter!

John Helmann @johnhelmann.bsky.social · Jul 28

Thanks Betül! I hope your students find this helpful.

John Helmann @johnhelmann.bsky.social · Jul 28

Metal ions are universally required for life, and many of the foundational principles of metal homeostasis have emerged from studies of microbial systems. In this review, I provide a introductory overview targeted to those new to the field.
#MicroSky #Metals

rdcu.be/eycU2

Microbial metal physiology: ions to ecosystems

Nature Reviews Microbiology - Metal ions are required for all cells, and their homeostasis relies on ancient mechanisms that facilitate their import, distribution and storage. In this Review,...

Reposted by John D. Helmann

Giedroc Lab @giedroclab.bsky.social · Dec 15

Our review on bacterial metallostasis is now online in Chemical Reviews! This collaboration by the Giedroc (@betainverse.bsky.social and @jsrocchio.bsky.social) and Capdevila labs delves into bacterial metal regulation. 🦠 #Microbiology #ChemicalReviews #BacterialMetallostasis doi.org/10.1021/acs....

Reposted by John D. Helmann

Dr Jess Buttress @jbuttresssci.bsky.social · Dec 21

So happy our pre-print on daptomycin mechanism of action is now out! Here, we present three main findings: i) daptomycin does not form large membrane pores in either B. subtilis or S. aureus, (1/3)

bioRxiv Microbiology @biorxiv-microbiol.bsky.social · Dec 21

The last resort antibiotic daptomycin exhibits two independent antibacterial mechanisms of action https://www.biorxiv.org/content/10.1101/2024.12.20.629673v1

Reposted by John D. Helmann

RCSB Protein Data Bank @rcsbpdb.bsky.social · Jan 6

After a remarkable 300 columns, David Goodsell has retired from the Molecule of the Month. We are very grateful for his service.
@jiwasa.bsky.social will continue the series, beginning with January's article on Assembly Line Polyketide Synthases
Details: cdn.rcsb.org/rcsb-pd...

EDUCATION CORNER: Molecule of the Month: Celebrating 25 Years of Storytelling and Announcing New Beginnings

After a remarkable 300 columns, David Goodsell has retired from the Molecule of the Month series. Janet Iwasa will be continuing the series for PDB-101.

Reposted by John D. Helmann

Dr Katherine Duncan @kateduncan.bsky.social · Jan 8

ICYMI: some microbiology societies/organisations/journals @naturemicrobiol.bsky.social @microbiologysociety.org @asm.org @biorxiv-microbiol.bsky.social @embojournal.bsky.social @femsmicro.bsky.social @official-smbe.bsky.social @stcmicrobeblog.bsky.social @who.int @biologists.bsky.social #microsky

Reposted by John D. Helmann

bioRxiv Microbiology @biorxiv-microbiol.bsky.social · Jan 17

The role of lipoteichoic acid in Staphylococcus aureus cell wall integrity https://www.biorxiv.org/content/10.1101/2025.01.16.633316v1

Reposted by John D. Helmann

Ákos T Kovács @evolvedbiofilm.bsky.social · Jul 17

Copper acquisition in Bacillus subtilis involves Cu(II) exchange between YcnI and YcnJ

#JBiolChem from @fisherlab.bsky.social
with @johnhelmann.bsky.social

www.jbc.org/article/S002...

Copper acquisition in Bacillus subtilis involves Cu(II) exchange between YcnI and YcnJ

The transition metal copper is biologically essential across all three domains of life. Several copper-dependent proteins and enzymes produced by the Gram-positive bacterium Bacillus subtilis have bee...

Reposted by John D. Helmann

Jan-Willem Veening @veeninglab.com · Jul 14

Now published, congrats Bevika, Kinki, Vincent, Florian and Paddy! #MicroSky
www.nature.com/articles/s41...

Reposted by John D. Helmann, Mart Krupovìč

STCmicrobeblog @stcmicrobeblog.bsky.social · Jul 12

must-read for phageophiles 👇 from sigal ben-yehuda's lab

"𝗬𝗷𝗯𝗛 𝗮𝗻𝗱 𝘁𝗵𝗲 𝗱𝗶𝘃𝗶𝘀𝗶𝗼𝗻 𝗺𝗮𝗰𝗵𝗶𝗻𝗲𝗿𝘆 𝗷𝗼𝗶𝗻𝘁𝗹𝘆 𝗮𝗰𝘁 𝘁𝗼 𝗰𝗼𝗻𝗳𝗶𝗻𝗲 𝗽𝗵𝗮𝗴𝗲 𝗰𝗼𝗺𝗽𝗼𝗻𝗲𝗻𝘁𝘀" in Gram-positives (𝘉. 𝘴𝘶𝘣𝘵𝘪𝘭𝘪𝘴)

🙏 @bacteriophile.bsky.social for pointing this out

#PhageSky #MicroSky

Figure 6. YjbH and the division machinery jointly act to confine phage components

(A) OF237 (ftsA-gfp, yjbH-mCardinal) cells were infected with SPO1, placed on an agarose pad, and followed by time-lapse fluorescence microscopy. Shown are images from FtsA-GFP (green), YjbH-mCardinal (red), overlay (1) of FtsA-GFP and YjbH-mCardinal, and overlay (2) of FtsA-GFP, YjbH-mCardinal, and phase contrast (gray), captured at the indicated mpi. Arrows highlight FtsA rings (yellow), YjbH foci (white), and their proximity throughout time (blue). Scale bar, 1 μm.

(B) An enlarged image corresponding to the bordered region in (A) (30 mpi, overlay [1]), with demarcated cell borders. Scale bar, 0.25 μm. An interpretive schematic illustrating YjbH (red) in proximity to FtsA (green) is depicted on the right.

Reposted by John D. Helmann

Ákos T Kovács @evolvedbiofilm.bsky.social · Jul 4

Happy to share this detective work by Rune Overlund Stannius now published in #mSystems

phenotype+genomes▶️GWAS▶️gene cluster for pigment production

Identification of widely conserved biosynthetic gene cluster involved in pigment production of Bacillus subtilis
journals.asm.org/doi/10.1128/...

John Helmann @johnhelmann.bsky.social · Jul 3

A new paper led by Ahmed Gaballa and Yesha Patel explores the pathways that reduce the dithiolopyrrolone (DTP) antibiotic thiolutin in B. subtilis. The active dithiol chelates intracellular Zn ions to impede growth.
#MicroSky #Zinc #Antibiotics

journals.asm.org/doi/10.1128/...

Schematic of reduction pathways for thiolutin, bacillithiol, and TrxAB

Reposted by John D. Helmann

Ákos T Kovács @evolvedbiofilm.bsky.social · Jul 3

The iron chelator pulcherriminic acid mediates the light response in Bacillus subtilis biofilms

@natcomms.nature.com by Kazuo Kobayashi and colleagues

www.nature.com/articles/s41...

The iron chelator pulcherriminic acid mediates the light response in Bacillus subtilis biofilms - Nature Communications

Non-photosynthetic bacteria often respond to changes in light through the action of photoreceptor proteins. Here, Kobayashi et al. show that Bacillus subtilis biofilms display light responses that dep...

Reposted by John D. Helmann

Molecular Microbiology Editors @molecularmicro.bsky.social · Jul 2

Tiffany Zarrella et al. provide new insights into the role of the bacterial second messenger cyclic di-adenosine monophosphate (c-di-AMP) in maintaining cell envelope homeostasis in Streptococcus pneumoniae.
#MicroSky #cyclic-di-AMP
onlinelibrary.wiley.com/doi/10.1111/...

Cyclic Di‐AMP Affects Cell Membrane Integrity of Streptococcus pneumoniae

When Streptococcus pneumoniae produces low amounts of the second messenger cyclic di-AMP (c-di-AMP), they do not survive in the presence of competence-stimulating peptide (CSP), which is used for tra...

onlinelibrary.wiley.com

Reposted by John D. Helmann

Molecular Microbiology @molmicrounihoh.bsky.social · Jul 1

👉 Cyclic Di-AMP Affects Cell Membrane Integrity of Streptococcus pneumoniae!

Molecular Microbiology | Microbiology Journal | Wiley Online Library onlinelibrary.wiley.com/doi/10.1111/...

#cdiAMPl @molecularmicro.bsky.social

Cyclic Di‐AMP Affects Cell Membrane Integrity of Streptococcus pneumoniae

When Streptococcus pneumoniae produces low amounts of the second messenger cyclic di-AMP (c-di-AMP), they do not survive in the presence of competence-stimulating peptide (CSP), which is used for tra...

onlinelibrary.wiley.com

Reposted by John D. Helmann

Molecular Microbiology Editors @molecularmicro.bsky.social · Jun 24

Jinich et al. present an important new resource for the Mtb community!
The Mycobacterium tuberculosis Transposon Sequencing Database (MtbTnDB) is an interactive web resource summarizing 150+ published screens.
#MicroSky #Mycobacterium #tuberculosis
onlinelibrary.wiley.com/doi/10.1111/...

The Mycobacterium tuberculosis Transposon Sequencing Database (MtbTnDB): A Large‐Scale Guide to Genetic Conditional Essentiality

Mtb transposon sequencing database is a unified resource for exploring conditional gene essentiality in Mycobacterium tuberculosis. By standardizing over 150 transposon sequencing screens, it enables...

onlinelibrary.wiley.com

Reposted by John D. Helmann

Molecular Microbiology Editors @molecularmicro.bsky.social · Jun 24

Stevens et al. describe the molecular basis for increased antibiotic tolerance in S. aureus COL: a prs mutation that reduces PRPP synthetase activity (leading to downregulation of pyrimidine, histidine, and tryptophan synthesis) plays a major role.
#MicroSky
onlinelibrary.wiley.com/doi/10.1111/...

Staphylococcus aureus COL: An Atypical Model Strain of MRSA That Exhibits Slow Growth and Antibiotic Tolerance due to a Mutation in PRPP Synthetase

COL is an unusual “model” strain of Staphylococcus aureus that exhibits slow growth and multidrug antibiotic tolerance. This phenotype is primarily due to a mutation in Prs, which synthesizes the cor...

onlinelibrary.wiley.com