Lecture 14: Contact Dependent Antagonism

contact dependent antagonism utilizes specialized _____ that deliver protein _____ in a contact-dependent manner

secretion machineries; toxins

contact-dependent antagonism also includes _____ bacteria that consume bacterial _____ for nutrients

predatory; prey

T6SS are found in gram _____ bacteria that deliver _____ in a contact-dependent manner

NEGATIVE; protein toxins

T6SS are evolutionarily related to _____

contractile phage tail tube and sheath

T6SS assemble in the _____ of the attacking cell then when the sheath contracts, the _____ pokes into the neighboring cell and delivers _____

cytosol; contracts; tube; effector toxins

the _____ of the T6SS forces the tube outward to penetrate the neighboring cell

contractile sheath

where are the effector toxins delivered into the recipient cell?

periplasm

the Sheath/Tube T6SS complex is anchored to a _____ complex

membrane baseplate

true or false: the sheath/tube can extend the entire width of the cell

TRUE

an unknown signal from the _____ of the T6SS triggers rapid _____ to _____ its length, does this require prey cells to be triggered?

baseplate; sheet contraction; 1/2; NO

true or false: Triggering of contraction of the T6SS sheet required prey cell

FALSE; does not require it to be triggered

a _____ of the T6SS punctures the _____ of the prey cell

sharp tip; membrane

during penetration, the _____ associated with the tip is delivered to the prey

toxin payload

can the contracted sheath be re-used?

yes, recycled by ClpV chaperone

why is T6SS a large energy investment?

lots of proteins are made and a large number of them are lost in the recipient

T6SS toxins are extremely _____, but the targets are always _____ and _____

diverse; conserved; essential

All species that have a T6SS are gram _____, most RECIPIENTS of it are gram _____

negative; negative

T6SS can destroy essential_____ of the recipient cell, degrade or inactivate essential _____, or modify essential _____

structures; metabolites; proteins

what are two examples of essential metabolites that are targeted by T6SS toxins

NAD and ATP

when pseudomonas and vibrio are grown together, which organisms T6SS dominates?

Pseudomonas

how does the Pseudomonas T6SS destroy vibrio?

targets cell wall structure → looses its shape

in the Pseudomonas and Vibrio co-culture, most will only attack after _____

attacked by someone else

the T6SS tail tube penetrates into the _____ and _____

periplasm; cytoplasm

true or false: ALL T6SS TARGETS are gram negative

FALSE: most but not all!

True or False: Attacker cells can damage their own kin with their T6SS

FALSE: they have immunity factors (will often accidentally fire into kin cells)

T6SS encode _____ proteins alongside their toxins

immunity

T6SS immunity proteins will _____ and _____ toxins _____ to injection

bind; neutralize; PRIOR

immunity proteins also protect _____ cells from intoxication

kin

some bacteria have been found to accumulate _____ as a stragety to subvert T6S

immunity genes

can immunity genes be present if the organism doesn’t have T6SS themselves?

YES (some accumulate them as protection)

T6S _____ can be shared between kin cells

components

the _____, _____, _____, and _____ proteins can all be transferred to a kin cell after injection by a T6SS

tip, effectors, tube, sheath

why might it be beneficial for a cell to attack their kin with their T6SS?

share components! Saves energy for kin who doesn’t need to make them all from scratch

growing a T6SS mutant with a WT kin will _____ the T6SS function

rescue (by sharing components!)

T6SS shapes the human _____ composition

gut community

many _____ microbes have T6SS and there are an estimates 1 billion T6S attacks per minute per gram of _____ in the _____

gut; feces; colon

when Flavobacterium johnsoniae and Bacteroides thetaiotaomicron are co-cultures, the _____ had the competitive advantage due to its _____

Flavobacterium; T6SS (when it got removed it had no advantage!)

contact dependent inhibition (CDI) systems are also known as _____

toxin on a stick

what three proteins are encoded in the CDI system?

secretion protein, filament/toxin, immunity factor

what is the CDI secretion protein gene called?

CdiB

what is the CDI filament/toxin gene called?

CdiA

what is the CDI immunity factor gene called?

CdiI

CdiA is a very _____ protein. The N-terminus forms a _____, while the C-terminus contains a _____

LARGE; long filament; toxin domain

the CdiA filament _____ secretion but the toxin domain remains _____ until there is _____

completes; un-secreted; contact with target cell

after contact with a target cell, the CdiA secretion is _____ and the toxin is _____

completed; delivered

True or False: the CDI system delivers several molecules of toxin

FALSE: ONLY ONE

the CdiB protein is responsible for facilitating _____

secretion of CdiA

where is CdiB protein found?

outer membrane

which end of the CdiA protein is the toxin domain?

C-terminus

what are the two predatory bacteria that we talked about?

Bdellovibrio and Myxococcus

Bdellovibrio is a _____ bacterium with _____ motility

small; rapid

Bdellovibrio infects, kills, digests, and lyses other _____ bacteria, including _____

gram negative; E. coli

Can Bdellovibrio replicate outside the host cell?

yes, but very slow

Bdellovibrio inserts through the _____ and replicates within the _____

outer membrane; periplasm

Bdellovibrio produces proteins that degrade __(4)___

RNA, DNA, lipids, proteins

eventually Bdellovibrio will _____ the host cell and released _____ replicated daughter cell

lyse; 4-6

To replicate its genome, Bdellovibrio uses the _____ nucleotides in addition to _____

hosts; making its own

after bdellovibrio invasion, it will _____ the membrane and begin to form a _____

reseal; deloplast

how does Bdellovibrio replicate?

non-binary fission, elongates to filament then divides multiple times

Can Myxococcus grow independently of a host?

YES! (it usually does!)

Myxococcus can grow independently of prey, but will also _____ and _____ on some bacterial species like _____

lyse; feed; E. coli

they do not _____ or _____ it’s prey, instead they travel together in large _____ swarms in search for food

invade; engulf; multicellular

Myxococcus attack prey cells _____ in something called a _____

together; wolfpack

upon finding a prey cell, Myxococcus will move _____ and _____ over the prey cells creating a _____ effect

back; fourth; rippling

Myxococcus have a _____ motility

rippling

True or False: Myxococcus has a T6SS and bacteriocins that are necessary for predation

FALSE: they have them, but no known component has been shown NECESSARY for predation

upon starvation, myxococcu can differentiate into _____ that contain a _____ form

fruiting bodies; dormant spore