(2.3) cytoskeleton

Ch 2 - Bacteria

what kinds of internal structures help to organize bacterial cells?

• cytoskeleton

• some cytoskeleton proteins involved in cell wall synthesis during cell division

  • FtsZ

  • MreB

• other cytoskeletal proteins involved with moving internal items (e.g., plasmids, magnetosomes)

  • ParM

• ff

cytoskeleton

series of internal proteins that assist in keeping everything in (or movinf it to) the right locations in cells

which cytoskeleton proteins involved in cell wall synthesis during cell division?

• FtsZ

• MreB

FtsZ

• tubulin-related protein

• polymerizes to form the Z-ring, a contractile structure at the inner membrane that marks the future division site and recruits cell wall-synthesis machinery

FtsZ labelling

how do the z-ring and cell wall-synthesis machinery work together?

the z-ring pulls inward as FtsZ breaks down (GTP hydrolysis), helping the cell wall machinery pinch the cell in two; it disappears after division and grets rebuilt for the next round

MreB

• bacterial “actin-like” protein

• behaves like actin in eukaryotes and forms long, helical filaments under the membrane

• found in almost all non-spherical bacteria (ex, rod shaped, esp in multicellular form) → helps them stay rod-shaped by guiding where the cell wall gets built

MreB labelling

ParM

dorects plasmid movement to either side of the cell, ensuring plasmid segregation

mangetospirillium bacteria

• white arrows →membrane that is surrounding the magnetism (that’s why these are considered ORGANELLES!)

• high-res image of the plasmid membrane surrounding the magnetosomes

• protein filaments found alongside the magnetosome chains: play a role in organizing them

MamK

• actin-like protein

• required for magnetosome formation

• when mutated, magnetosome-associated filaments disappeared

what happens when mamK gene is disrupted?

• gene was fused to a fluorescent protein (GFP)

• cell membrane is stained with red fluorescent dye

magnetosomes are no longer in the same line/ alignment like in image B

2.3 checkpoint