Mitchell O'Connell

My lab was stoked to play a role in this fun collaboration with
@doc-jlmeier.bsky.social , Colin Wu and Schraga Schwartz labs among others, where we try to figure out the role of ac4C tRNA mods in mammalian stress signaling. See below for an excellent summary from Jordan (thanks!)

21.03.2025 15:22 — 👍 13    🔁 1    💬 0    📌 0

How does it enhance phage defence? Pfu/mL +/- Csx28. 10000x improvement in phage defence by small membrane protein. Bacterial growth with addition of phage. Bacteriostatic effect? Forms an octamerif forward in DDM, now nanodisc... ligand gating of channel? Depolarisation assay? Dye that is weakly fluorescent when cells are polarised, loss of polarisation increase fluor. DiBAC4. 40% depolarised with cas13b and csx28. No complex formation. Cleaved ssRNA to open this channel. tRNA anticodon loop cleavage by target-activated CRISPR-Cas13a. Cleavage products from tRNAs. Pull down monomeric Csx28 no pulldown; Octomer- enrichment of ssRNA in pull-down. Pull downs on grids - 8 mol of tRNA degradation products bound to Csx28. Where is the tRNA cleaved? cmo5U? Xm5U? Keio collection - screened against tRNA modification enzyme kos. Modification of the wobble residue prevents the phage defence. Csx27 4 TM protein next. Similar function to Csx28. Alphafold2 to identify similar RNA gated ion channels.

Session 9: Mitch O'Connell bacterial/bacteriophage arms race. Small RNAs to mount an adaptive MGE immune response. CRISPR RNA defence systems. How does Cas13 work as an enzyme to target RNA? Csx28 128 aa protein, TM, cyt. Co-opt membrane effectors? 👏 #LorneProteins2025

11.02.2025 23:25 — 👍 7    🔁 2    💬 0    📌 0

Preprint alert! Brandon a shared student between my lab and @pjmurphy249.bsky.social 's has uncovered some biases in ChIP-seq that means we may be missing signal in heterochromatic regions of the genome, and tagmentation based techniques can overcome this. See below for Patrick's fantastic summary:

05.02.2025 21:35 — 👍 5    🔁 0    💬 0    📌 0

And I will sleep when I'm dead! Big fan, and need to revisit. I haven't seen this interview, thanks for the link

22.11.2024 02:14 — 👍 1    🔁 0    💬 0    📌 0

a wonderful performance, thanks for sharing :)

22.11.2024 02:01 — 👍 1    🔁 0    💬 1    📌 0

I will check out. I've been on a Tom Petty binge lately! I can't get past this performance, cuts me to the core: www.youtube.com/watch?v=4O7a...

22.11.2024 01:48 — 👍 1    🔁 0    💬 1    📌 0

Thanks! @bronwynalucas.bsky.social! He's such a joy <3

18.11.2023 23:35 — 👍 1    🔁 0    💬 0    📌 0