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1. Nascent flagellar basal bodies are immobilized by rod assembly in Bacillus subtilis

   https://doi.org/10.1128/mbio.00530-25  

   Dunn, Caroline M; Foust, Daniel J; Gao, Yongqiang; Biteen, Julie S; Shaw, Sidney L; Kearns, Daniel B (June 2025, mBio)

   Salama, Nina R (Ed.)

   ABSTRACT Flagella are complex, trans-envelope nanomachines that localize in species-specific patterns on the cell surface. Here, we study the localization dynamics of the earliest stage of basal body formation inBacillus subtilisusing a fluorescent fusion to the C-ring protein FliM. We find thatB. subtilisbasal bodies do not exhibit dynamic subunit exchange and are largely stationary at steady state, consistent with flagellar assembly through the peptidoglycan (PG). However, rare mobile basal bodies were observed, and the prevalence of mobile basal bodies is elevated both early in basal body assembly and when the rod is mutated. Thus, basal body mobility is a precursor to patterning, and we propose that rod polymerization probes the PG superstructure for pores of sufficient diameter to permit rod transit. Furthermore, mutation of the rod disrupts basal body patterning in a way that phenocopies mutation of the cytoplasmic flagellar patterning protein FlhF. We infer that rod synthesis and the cytoplasmic regulators coordinate flagellar assembly by interpreting a grid-like pattern of pores, pre-existent in the PG. IMPORTANCEBacteria insert flagella in a species-specific pattern on the cell body, but how patterns are achieved is poorly understood. In bacteria with a single polar flagellum, a marker protein localizes to the cell pole and nucleates the assembly of the flagellum at that site.Bacillus subtilisassembles ~25 basal bodies over the length of the cell in a grid-like pattern and lacks proteins required for their polar targeting. Here, we show thatB. subtilisbasal bodies are mobile soon after assembly and become immobilized when the flagellar rod transits the peptidoglycan (PG) wall. Moreover, defects in the flagellar rod lead to a more-random distribution of flagella and an increase in polar basal bodies. We conclude that the peritrichous patterning of flagella ofB. subtilisis different from the polar patterning of other bacteria, and we infer that theB. subtilisrod probes the PG for holes that can accommodate the machine. 

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2. Arabidopsis pollen tube integrity and sperm release are regulated by RALF-mediated signaling

   https://doi.org/10.1126/science.aao3642  

   Ge, Zengxiang; Bergonci, Tabata; Zhao, Yuling; Zou, Yanjiao; Du, Shuo; Liu, Ming-Che; Luo, Xingju; Ruan, Hao; García-Valencia, Liliana E.; Zhong, Sheng; et al (December 2017, Science)
3. R1 retrotransposons in the nucleolar organizers of Drosophila melanogaster are transcribed by RNA polymerase I upon heat shock

   https://doi.org/10.1080/21541264.2018.1506682  

   Raje, Himanshu S.; Lieux, Molly E.; DiMario, Patrick J. (May 2018, Transcription)
4. Bald Cypress ( Taxodium distichum ) Knees Are Methane Sources Controlled by Geomorphology, Climate, and Hydrologic Extremes

   https://doi.org/10.1029/2025JG008996  

   Ross, Skylar K; Klauss, Niklas; Miles, Marissa; Khatiwada, Kabi Raj; El_Masri, Bassil; Runkle, Benjamin_R K; Stinchcomb, Gary E; Moon, Jessica B (October 2025, Journal of Geophysical Research: Biogeosciences)

   Abstract While woody root structures, such as bald cypress (Taxodium distichum) “knees,” can act as conduits of methane (CH₄), little has been done to explain variation from this flux pathway. We captured spatial (i.e., across knee surface, within sites, between sites) and temporal dynamics of CH₄from knees, and built empirical models to predict the contribution of knees to net CH₄fluxes. Knee and soil CH₄fluxes were measured across seasons within the lower Mississippi Alluvial Valley in a main channel (semi‐permanently flooded), side channel (seasonally flooded), and a reservoir edge (artificially flooded). Knees were a net source of CH₄across all seasons, even during periods of soil CH₄uptake. During periods of high knee CH₄efflux, fluxes varied across the knee surface, decreasing with height from the ground. Knee CH₄fluxes at the main and side channels decreased during a severe drought and increased ∼ ten‐fold in summer and two‐fold in winter following flooding events. At the reservoir edge, knee fluxes differed between the controlled draw up and draw down at the same water level, likely due to differences in temperature and oxygen availability. Knee CH₄fluxes were positively correlated with water level (measured from subsurface wells, above ∼−70 cm in the soil profile) and subsurface temperature, but the strength of the relationships differed across geomorphic positions. Cypress knees appear to be an important contributor to wetland CH₄efflux and accounting for the density of knees is needed to upscale their fluxes and better understand their ecosystem contribution. 

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5. YodL and YisK Possess Shape-Modifying Activities That Are Suppressed by Mutations in Bacillus subtilis mreB and mbl

   https://doi.org/10.1128/JB.00183-16  

   Duan, Yi; Sperber, Anthony M.; Herman, Jennifer K.; Henkin, T. M. (July 2016, Journal of Bacteriology)

   ABSTRACT Many bacteria utilize actin-like proteins to direct peptidoglycan (PG) synthesis. MreB and MreB-like proteins are thought to act as scaffolds, guiding the localization and activity of key PG-synthesizing proteins during cell elongation. Despite their critical role in viability and cell shape maintenance, very little is known about how the activity of MreB family proteins is regulated. Using a Bacillus subtilis misexpression screen, we identified two genes, yodL and yisK , that when misexpressed lead to loss of cell width control and cell lysis. Expression analysis suggested that yodL and yisK are previously uncharacterized Spo0A-regulated genes, and consistent with these observations, a Δ yodL Δ yisK mutant exhibited reduced sporulation efficiency. Suppressors resistant to YodL's killing activity occurred primarily in mreB mutants and resulted in amino acid substitutions at the interface between MreB and the highly conserved morphogenic protein RodZ, whereas suppressors resistant to YisK occurred primarily in mbl mutants and mapped to Mbl's predicted ATP-binding pocket. YodL's shape-altering activity appears to require MreB, as a Δ mreB mutant was resistant to the effects of YodL but not YisK. Similarly, YisK appears to require Mbl, as a Δ mbl mutant was resistant to the cell-widening effects of YisK but not of YodL. Collectively, our results suggest that YodL and YisK likely modulate MreB and Mbl activity, possibly during the early stages of sporulation. IMPORTANCE The peptidoglycan (PG) component of the cell envelope confers structural rigidity to bacteria and protects them from osmotic pressure. MreB and MreB-like proteins are thought to act as scaffolds for PG synthesis and are essential in bacteria exhibiting nonpolar growth. Despite the critical role of MreB-like proteins, we lack mechanistic insight into how their activities are regulated. Here, we describe the discovery of two B. subtilis proteins, YodL and YisK, which modulate MreB and Mbl activities. Our data suggest that YodL specifically targets MreB, whereas YisK targets Mbl. The apparent specificities with which YodL and YisK are able to differentially target MreB and Mbl make them potentially powerful tools for probing the mechanics of cytoskeletal function in bacteria. 

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