C7- Fungal Collaborators And Competitors

Question 1

What is ammensalism

Answer 1

Where one has negative effect on the other with no gain unlike parasitism

Question 2

What sorts of things can bacteria modulate of fungi

Answer 2

Antifungal susceptibility, capsule formation, growth, biofilm, hyphal development

Question 3

What sorts of things can fungi modulate on bacteria

Answer 3

Growth, antibiotics, virulence traits like iron acquisition, quorum sensing and biofilm

Question 4

Candida albicans and pseudomonas aeruginosa - example 1

Question 5

What is pa found in

Answer 5

Cystic fibrosis lung

Question 6

What do it do to hyphae directly

Answer 6

Binds hyphae in response to quorum molecule homoserine lactose and kills them

Question 7

What phenazines can pa release

Answer 7

Pyocyanin and pyorubin

Question 8

What are these important according to major study on morphology effects and how do these phenazines do this

Answer 8

Block biofilm formation and hyphal formation

By repressing respiration in candida

Question 9

Why does phenazine increasing o2 levels in biofilm important (found during experiments)

Answer 9

Because they’re usually anaerobic to allow colonies of anaerobes to develop

Question 10

How did they find it was stopping respiration

Answer 10

Dye TTC which turns red by reduction by the ETC didnt happen

Lack of red in presence with phenazines

Question 11

How does conversely, pa induce fluconazole resistance of candida

Answer 11

Homoserine lactose induces efflux pump expression

Question 12

Which structure is similar to homoserine lactone which indicates its mechanism of action on hyphae (also blocks hyphal growth)

Answer 12

Farnesol

Question 13

Which gene do pa have for iron acquisition which is compromised by fungi

Answer 13

Pyochelin genes

Question 14

Which lung fungi can block growth and biofilm formation of pa important for virulence in Cystic fibrosis

Answer 14

Af through its gliotoxin

Question 15

Example 2 - lactobacillus app and c. Albicans

Question 16

What product of gut lactobacillus masks b glucan (immune escape) and can be used as a c source for growth of ca

Answer 16

Lactate

Question 17

How does it remodel the cell wall

Answer 17

Through Gpr1 sensor of lactate and signal transduction to remodel b glucan

Question 18

Which lactobacillus has chitinase activity which blocks yeast to hyphal formation which is good for us in contrast

Answer 18

Rhamnosis GG

Question 19

In mouse model, what does scfa (also produced by commensals like lactobacillus) like butyrate help to stop overgrowth which is stopped in antiobiotic treatment (potentially important in Ibd)

Answer 19

Filamentation and biofilm formation

Question 20

T6ss and microbial competition

Question 21

Explain the structure of a t6ss

Answer 21

You have a sheath which contracts during firing event
Then base plate
Then a membrane complex/HCP tube which pushes effector through the vgrg and paar(needle end)

HCP-vgrg-paar structure pushes effectors into target cell

Question 22

What depolymerises the sheath to decontract it after a firing event, allowing it to reset for new firing event

Answer 22

TssH

Question 23

What do resistant bacteria have which neutralises effector proteins

Answer 23

Immunity proteins which bind

Question 24

Give a few examples of t6ss use

Answer 24

Inter bacterial competition
Nutrient scavenging
Killing of fungi
Host cell invasion/killing

Question 25

Which bacteroides can control other popn of bacteroides like b theta or ovatus which don’t have it through t6ss

Answer 25

Fragilis

Question 26

What is resistant to this killing

Answer 26

Proteo bacteria like ecoli

Question 27

Give example of a bacteria which uses its t6ss to kill fungi in inter kingdom competition

Answer 27

Serratia marcescens

Question 28

Incubation of sm with the sach cerevisiae, c glabrata and c albicans does what compared to t6ss mutants

Answer 28

Kills them

Question 29

Which effector previously invoked in bacterial bacterial competition was later found to only affect c albicans killing not the other 2

Answer 29

Tfe1

Question 30

How did they later identify again tfe 1 and other like tfe2

Answer 30

They did a ko of tsse component of the base plate so that effectors would accumulate in fungi Then did quantitative proteomics on wt vs tsse mutant should see toxin accumulation and found tfe1 and tfe2 hits and proteins like hcp which validated the t6ss model

Question 31

What does ko of tfe2 effector do unlike tfe1 ko

Answer 31

Partially Rescues ca, cg and sc not just ca

Question 32

What does ko of both effectors show unlike if only 1 is ko causing partial rescue

Answer 32

Same phenotype as having a t6ss ko (large survival)

Question 33

Doing cryo-tem of sm with yeast Candida/sach cells shows what

Answer 33

Necrotic cells/ lysed in presence of t6ss but not in tsse mutant and in contact Ko of tfe1 showed rescue aswel of necrosis/lysis of Candida albicans Loss of granules in tfe2 mutant when incubated with glabrata and sach cer

Question 34

When you express a plasmid into the fungi with tfe1 or 2 into s. Cerevisae what happened. Was tfe2 found to kill the cells or jus cause growth arrest of s.cer specifically (which stopped when stopped tfe2 expression)?

Answer 34

Tfe1 had no toxicity effect at low levels but tfe2 always toxic Found in liquid culture that once you stop tfe2 exp in cerevisiae then growth is rescued so it isn’t killing them.

Question 35

How did studies on sach cer find the mechanism tfe1 uses is membrane transport interruption/ membrane depolarisation

Answer 35

Dibac4 staining which stains cells which aren’t respiring/no etc/membrane depolarisation (opposite of ttc) Showed staining of sach cer expression of tfe1

Question 36

Are hyphal tup1 ko candida also killed by sm or just yeast

Answer 36

Both

Question 37

How is tfe1 as a membrane depolarising toxin also supported by quantitative proteomics when candida incubated with the diff effectors wt/mutant

Answer 37

No target proteins which are upreg or downregulated in its presence (no diff in mutants vs wt) So suggests it targets membrane not specific proteins

Question 38

How many proteins are differentially upreg or downregulated in tfe2 presence

Answer 38

30

Question 39

What are downregulated vs upregulated

Answer 39

Sulfate assimilation parhway downregulated (way sulfur is acquired for growth) Upreg of arginine synthesis

Question 40

What does this indicate

Answer 40

Imbalance of nutrients/ depletion of nutrients leading to starvation, autophagy and death

Question 41

Other fungi- bacteria interactions

Question 42

Which bacteria in oral mucosa constantly found in biofilm with Candida albicans to form plaques or caries/tooth decay

Answer 42

Strep mutans

Question 43

How is it suggested this biofilm forms

Answer 43

Through farnesol signalling of candida which induces glucosyltransferases by mutans to increase ecm component of biofilms

Question 44

Which 2 bacterial commensals found in mouse models sufficient in stoping candida overgrowth/colonisation (eg in Ibd) - FAN 2015

Answer 44

Blautia producta (firmicute) and b theta

Question 45

How in mice models after 2 weeks was ca undetected. The same molecule also reduced invasive disease death by 50% in mouse model

Answer 45

Through inducing ll37 whcih is anti-candida by hif1a tf induction

Question 46

Does proteobactedia have the same effect through ll37

Answer 46

No- showing importance of immunomodulatory firmicute and bacteroidetes with other examples like b fragilis and clostridia/f. Prausnitzii

Question 47

Why is hoarau 2016 been controversial

Answer 47

Because s. Marcescens shown to have a t6ss which would suggest it is not mutualistic with candida

Question 48

Why are gpi anchored mannoproteins with n-mannan being on the outer cell wall very important

Answer 48

To hide b glucans which are very immunogenic

Question 49

Which author / research study first coined the idea that l Reuteri in mouse models are critical for trp metabolism induced ilc3 which release il22- which they found to have antagonistic effects on c albicans (example of a ammensalistic relationship)

Answer 49

Zelante 2013