Lecture 1A: STAGES OF SPORULATION CYCLE IN B. subtilis Flashcards
Key points of stage 0+1: vegetative growth
- B. subtilis is in its normal vegetative growth phase, dividing by binary fission.
*Sporulation begins when nutrients (especially carbon and nitrogen sources) become limited.
*The master regulator Spo0A is activated, initiating sporulation.
gene that
produces protein KIN A
Kin A (gene)
Upon
nutrient starvation, it inhibit the
anti-kinase activity of kipI
KIN A (protein)
- anti-kinase protein
- present in many
bacterial domain
kipI (protein)
What happens when there is nutrient
starvation
there is a
translation of mRNA to
make KIN A protein
What happens if the anti kinase activity
of kipI is inhibited
activation of SpoO A (meaning phosphorylated siya)
the
4th and 5th genes
respectively of seven
cistron operon made up
of 6- 7 genes under 1
promoter
kipI and kipA
It is triggered when there is a combined actions of kipI and kipA
regulatory pathway
known as the
sporulation
phosphorelay
cassette of
genes
Operon
What happens if there is no harsh
condition
the cell
turns on the kipI
Key points of 2: Axial filament and asymmetric cell division: Pre-spore
- The chromosome elongates and forms an axial filament stretching across the cell.
- This ensures that both the future spore (forespore) and the mother cell receive genetic material.
- The cell divides asymmetrically, forming a small forespore and a larger mother cell.
- The forespore receives only about 30% of the chromosome, with the rest translocating later.
- INVOLVES
DIFFERENTIATIO
N PROGRAM - Last about 5 hours
on the average - It involves 383
genes, epistatically
controlled by
transcription
factors: sigma E, F,
G - Highly regulated
controlled process
STAGE 2 AND 3
How many genes are involved in stage 2 and 3 and what transcription factors control these genes
383
genes.
transcription
factors: sigma E, F,
G
Why differentiation is
asymmetric division in stage 2 smaller than the
rest of the cell
BECAUSE
fore-spore is much
Formation of the
axial filament pre
spore
feeding tube
formed by the
mother cell and
separated from
future fore-spore by
a closing Z-ring to
form a tunnel
Sporangium
When pre-spore is
finally form , it
takes approx. ___% of 1 chromosome
and the __% of the
chromosome lies on the feeding tube
particularly in
protein SpoIII E
- 30%
of 1 chromosome - 70% of the
chromosome on the feeding tube
particularly in
protein SpoIII E
SpoIII E is also called
translocase)
Key points in stage 3: engulfment of pre-spore
- The mother cell engulfs the forespore, surrounding it with a second membrane.
- The forespore is now enclosed within the mother cell’s cytoplasm.
Stage 3 is accompanied by
simultaneous
activity of a what
modified
peptidoglycan
modified
peptidoglycan contains:
modified sugar,
muramic delta lacta
, and has low level
of peptide-cross
linkages glycan
strands
Stage 4: Cortex Formation
- A thick peptidoglycan cortex is synthesized between the two forespore membranes.
- This layer protects against heat and desiccation.
the
proteins
responsible for the
stage 5 and 6 are
already synthesize
by what stage
the end of stage
4
Stage 5: Coat Formation & Maturation
- A protein spore coat forms around the forespore, adding resistance to chemicals and enzymes.
- Dipicolinic acid (DPA) and calcium accumulate, stabilizing DNA and enhancing heat resistance
How many proteins are involved in formation of spore coat
Approx. 70 proteins
Many of the 70
protein actually
migrated to the
spore surface at
the time of
engulfment(stage2)
Stage 6: lysis
The mother cell undergoes lysis, releasing the mature endospore into the environment.
What is synthesized in stage 6
DPA(derived from
(L-aspartic)
Most layer of the
spores are composed of
Coat protein
