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On to Caulobacter !

On to Caulobacter !. 0.7 um in diameter 2-3 um long. Swarmer cell Stalk cell. The stalked bacterium. Graphical Representations of the Genome. 4,016,942 bp 3767 ORFs ( CW and CCW). A Sticky Wicket.

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On to Caulobacter !

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  1. On to Caulobacter! 0.7 um in diameter 2-3 um long Swarmer cell Stalk cell The stalked bacterium

  2. Graphical Representations of the Genome 4,016,942 bp 3767 ORFs (CW and CCW)

  3. A Sticky Wicket

  4. Wild-type Vibriod Cells Transposon Insertion Complementation by Normal Gene Shaping a Crescent-Shaped Cell: Crescentin Elongated stationary phase cells 2 um

  5. Cresecentin Filaments Shape Caulobacter optical sections of stationary phase cells

  6. Crescentin is an Intermediate Filament Ortholog

  7. MreB Directs Wall Synthesis as in E. coli Xylose-regulatable MreB Turned Off After Switch to Xylose-Free Medium

  8. MreB Also Positions the Chromosomes Depletion and Overexpression Both Disturb Partitioning

  9. And FtsZ is Involved in Division 40/60 split xylose medium glucose medium complementation by a wild-type ftsZ allele Xylose-regulatable FtsZ

  10. Prokaryotes Contain Orthologs of All Three Major Filamentous Networks of the Eukaryotic Cytoskeleton EM scale bars 100nm Light microscope bars 2 um

  11. The Caulobacter Life Cycle ~150 min

  12. Non-synchronized average level Transcriptome Changes During the Cell Cycle Expression of 16% of the Genome is Cell-Cycle Regulated

  13. Turning it on, turning it over Pulse/Chase

  14. Cell Cycle Regulation Is Mediated by CtrA CtrA controls 38 direct and 144 indirect targets (~7% of the genome)

  15. Resynthesis Represses the ORIs Cell Cycle Expression of CtrA Proteolysis Frees the ORI SW ST

  16. Asymmetric Localization of Other Key Determinant Molecules Proteolysis In SW Kinases Localize to ST Localize to SW Localize to poles and disperses

  17. Movie Localization of DivJ During the Cell Cycle Localization of DivJ::GFP to the ST pole during division

  18. MreB Organizes Polarity

  19. Another master Regulator, GcrA, Partitions Oppositely from CtrA GcrA is a Positive Regulator of DNA Replication in ST

  20. The CtrA/GcrA Master Cycle CtrA represses GcrA expression Proteolysis of CtrA releases GcrA expression GcrA expression turns CtrA expression back on CtrA represses expression of itself and GcrA ST molecular identity Taking Different Paths SW molecular identity Literally Sorting out molecular identity

  21. A Few Questions for Thought • Describe the Caulobacter life cycle, noting key cellular landmarks of each stage of development. • Extend your discussion of the prokaryotic cytoskeleton from E. coli to include Caulobacter’s crescentin. • Propose a model based on the Min operon system for how Caulobacter reproducibly divides in an unequal fashion. • Discuss the critical role of CtrA in the developmental of Caulobacter, including a sense of when, where and why this protein is active as well as the rich diversity of targets that it regulates (and the consequences of those interactions). • Describe how expression of CtrA and GcrA alternate to drive the developmental cycle of Caulobacter. • Explain how differential inheritance of transcription factors and kinases can constrain two daughter cells to different developmental fates.

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