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Mucosal Surfaces > L5 Glycan Metabolism > Flashcards

L5 Glycan Metabolism Flashcards

1
Q

Where do glycans get broken down

A

Colon

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2
Q

Whaf is dietary fibre eg from plants

A

Glycans which are indigestible by our enzymes

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3
Q

Gice some plant cell wall polysaccharides

A

Xylan

Pectin

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4
Q

Are plant cell wall glycans soluble or insoluble

A

Both

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5
Q

Give some oligo saccharide vegetable examples

A

Broccoli and beans have raffinose

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6
Q

What type of starch isnt digested by our amylqses

A

Resistant starch

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7
Q

What are fructans and where can you find them

A

Fructose polysaccharides wg in garlic but also put into probiotics

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8
Q

What process produces waste products scfa

A

Anaerobic fermentation

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9
Q

What are the 3 types of scfa and who makes them

A

Butyrate - firmicutes
Proprionate- bacteroidetes
Acetate- all

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10
Q

What are the major functions of butyrate by firmicutes

A

Anti cancer effects and providing energy for colonocytes

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11
Q

What are the major functions of proprionate by bacteroidetes

A

Anti inflam (smith et al 2013)

Glucose homeostasis

Reduce appetite

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12
Q

What is the function of acetate

A

Lower ph to block pathogens

Also affects lipogenesis

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13
Q

Which article discusses butyrate anti cancer functions

A

Chen et al 2018

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14
Q

What does chen et al 2018 outline

A

By blocking hdacs, butyrate hyperacetylayes histones which helps regulate apoptotic and cell survival enzymes

Interferes with apoptotic pathways

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15
Q

Why does ulcerstive colitis occur in rectum and distal colon

A

Lower levels of scfa there

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16
Q

Why is there a smaller mucus layer with mucin in si and stomach

A

Erosion due to lack of anaerobic fermembration there for glycan utilisation so they start to use mucins

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17
Q

Which articel outlines wrosion of mucin layer due ti low dietary fibre

A

Desai 2017

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18
Q

Give an example of bacteria which can utilise o glycan mucins (desai 2017)

A

Bacteroides theta

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19
Q

What does muc2 deficiency on epi cells cause

A

Colon cancer and inflammation (desai 2017)

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20
Q

What happens where theres low fietary fibre to the microbiota diversity which happens in ibd

A

The mucin utlising bacteria outcompete the rest (usually bacteroides)

21
Q

Why can some utlisie mucins

A

Express cazymes which can degrade mucus polysaccharides

22
Q

Give some examples bacteroidetes (-)

A

Bacteroides theta,ovatus,fragilis, prevotella

23
Q

Give some dxamples of firmicutes (+)

A

Clostridium, roseburia, eubacterium

24
Q

Which other bacteria are for fermentation

A

Actinobscteria like bifido

25
Q

Which bacteria tend to have more specialised roles

A

Firmicutes and actino

26
Q

What bacteroides prefer mucins for energy

A

B. Thetaiotaomicron

27
Q

Which bacteroides prefer plant polysaccharides like xylan

A

Bacteroides ovatus

28
Q

Can bacteroides use mog

A

Yes

29
Q

Which part of genome is responsible for bacteroidetes utlisation of glycan from OM

A

Puls - polysaccharide utilisation loci

30
Q

What do puls encode

A

Different SUS like systems (starch utilisation systems) which allow import and degradation of glycans.

31
Q

Why is there many puls

A

Nrcause many different sus like systems speicfic for specific glycans

32
Q

How many puls do b thetaiotaomicron encode

A

88 for diff glycans

33
Q

What sus protein is the importer transembrane protein

A

Sus C

34
Q

What does sus c form complex with and why

A

Sus d lipoprotein which bunds glycan larger than 5 sugars long. Sits on top of sus C like a lid

35
Q

What is sus G like proteuns

A

The surface enzymes hsed to degrade larger polysaccharides into smaller

36
Q

What enzyme is susG

A

Gh13 for starch

37
Q

What associates with sus c and d which allows sensing of glycans by bacteroidetes

A

The sensor regulators all for diff glycans

38
Q

What do glycans further get degraded by from puls

A

Periplasmic enzymes

39
Q

What is needed on c/d complex ti bind glycans wkth high affinity unlike susD so that glycans wre available

A

SGBP - surface glycan binding proteins (SusE like)

40
Q

Give an exmaple of a surface cazyme needed for the cd mechanism

A

B theta need dextranase to breakdown dextran so rhag it gets imported. Witjout it the b theta couldnt grow

41
Q

Why are firmicutes more specialised

A

Less gh and pl

42
Q

What type of mechanism instwad of puls do firmicutes have

A

Abc atp birning cassettes on inner mmebrnae usint atp hydrlysis

In larhe cell wall have Glycanases like gh13 for starch. Theyre upregulated accordingly

43
Q

What do the glycanssws in cell walls of firmicutes have to bind glycans

A

Carbohydrate binding molrcules CBM

44
Q

What do firmicutes prefer over bacteroidetes and give an exmaple

A

Insoluble polysaccharides. Eg ruminococci have multienzyme complexes which breakdown starch and cellulose called cellulosome and amylosome

45
Q

Which bacteria need firmicutes and bacteroudetes ti break down poly into okigo for use

A

Bifidonacterium

46
Q

Do bifido have similar to abc transporter mechanism

A

Yes. Rhey also have glycansses and the surface binding proteins

47
Q

What is the bifido interaction with f and b called

A

Cross feeding

48
Q

Give an example of how bacteroides ovatus is used to co culture bifido asolescentis on simple xylans/ wheat

A

B ovatus can utlisie complrx and simple wheat xylans from planr polysaccharides. This breakdown into simple oligo xylans can be used to grow bifido adolescentis

Mucosal Surfaces (33 decks)

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