Sean Czerwinski
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sczerwinski.bsky.social
Sean Czerwinski
@sczerwinski.bsky.social
510 followers 950 following 33 posts
Ph.D. Candidate at GSU with @jamesgurney.bsky.social - Phage researcher that is open to losing a capsid and genome on occasion. Evolutionary medicine in the face of AMR #PhageSteering #HAs
Avid concert goer. Footy fan. Phage phan.
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sczerwinski.bsky.social
Phold is a fantastic tool and my go to for detailed annotation and visualization of phage genomes. Congrats!
August 9, 2025 at 1:58 PM
sczerwinski.bsky.social
I’d love to chat more about this work and the potential of phage steering in complex, drug-resistant infections. Come find me at my poster at ASM Microbe 2025 - Sunday, June 22nd!
June 10, 2025 at 9:14 PM
sczerwinski.bsky.social
We found SNPs in pilR and pilZ, key regulators of T4P biogenesis. One line had a SNP in pqsR, a transcriptional regulator of quorum sensing in PA, because is it ever not quorum sensing? These mutations conferred resistance to the phage and attenuated T4P function!
Mutations in key regulatory factors of T4P biogenesis confer phage resistance. (A) PilR serves as the response regulator of pilA transcription. The sensor kinase, PilS, phosphorylates PilR, activating it, which, in turn, activates transcription of pilA, which encodes for the major pilin subunit, PilA. (B) PilZ regulates T4P biogenesis. By binding to the extension ATPase, PilB activates shaft polymerization. PilZ and FimX are necessary for PilB activation. (C) Without PilZ binding, PilB remains inactive, and energy is not generated for shaft assembly. (D) Defective PilR does not activate transcription of pilA, no PilA subunits are synthesized, and thus, the shaft is not assembled.
June 10, 2025 at 9:13 PM
sczerwinski.bsky.social
Curiously, lines evolved in the presence of S. aureus showed greater SNP diversity conferring resistance to the phage. See the bold SNPs...
Chromosomal single-nucleotide polymorphisms (SNPs) defined for all co-evolution condition replicates and the ancestral PAO1. SNPs were determined using breseq (version 0.31). SNPs of two variations in 5 out of 5 (5/5) +Luz19 co-evo replicates and 3/5 +SA+Luz19 co-evo replicates. In all but one of these replicate sequences, the SNP in pilR is C192Y (TGC → TAC). Replicate B of the +Luz19 condition had a different SNP in pilR, P189Q (CCG → CAG). Of the replicates in the two conditions that were subject to co-evolution with Luz19, two lacked an SNP in pilR, both in the +SA+Luz19 condition. Replicate B instead had a 197 bp deletion in pilZ. Replicate A of +SA+Luz19 was the only replicate co-evolved alongside Luz19 that sequencing did not reveal a pil gene mutation; instead, a PQS system mutation was identified in pqsR.
June 10, 2025 at 8:43 PM
sczerwinski.bsky.social
Thanks very much!
May 10, 2025 at 2:47 PM
sczerwinski.bsky.social
Really exciting preprint, congrats! I’ve been working on identifying novel phages from P. aeruginosa CF isolates, but suspect some (or many) may be missed by my pipeline. I’d love to try Phager. I saw phager.py mentioned and assume the SI is pending, but any chance early access might be possible?
May 8, 2025 at 9:24 PM
Reposted by Sean Czerwinski
evolvedbiofilm.bsky.social
Susan today explains contractile injection systems of Streptomyces
- see their cool paper in @naturemicrobiol.bsky.social
www.nature.com/articles/s41...

#KNVM2025
Cytoplasmic contractile injection systems mediate cell death in Streptomyces - Nature Microbiology
Characterization of a contractile injection system (CIS) in the Gram-positive multicellular model organism Streptomyces coelicolor finds that CIS mediate cell death in response to stress that impacts ...
www.nature.com
April 2, 2025 at 11:54 AM