Lecture 8 -- Peptidoglycan/Lipopolysaccharide/Lipoteichoic Acid

Question 1

inside the cell (must be moved outside except for mutans and levans)

Answer 1

where are extracellular polysaccharides synthesized?

Question 2

acivate sugar –> transfer to a lipid (undecaprenyl phosphate) –> move across membrane & possibly assemble outside

Answer 2

Steps for extracellular polysaccharide transfer from inside to outside the cell

Question 3

Peptidoglycan, Teichoic Acid, and Lipoteichoic acid (LPS)

Answer 3

What uses the Wyz mechanism?

Question 4

LPS

Answer 4

Which uses both the ABC transporter mechanism and the WYZ mechanism?

Question 5

contributes to cell shape, rigidity, and resistance to osmotic pressure

(5-20% of cell envelope in Gram-negative)
(90% of cell envelope in Gram-positive)

Answer 5

Functions of peptidoglycan

Question 6

lots of variation in peptidoglycan; fairly constant composition and structure of peptidoglycan

Answer 6

Gram positives; Gram negatives

Question 7

punches holes in peptidoglycan and the high osmotic pressure causes large bubbles to form

Answer 7

treating non-typeable bacteria with lysosome

Question 8

the o antigen in the LPS layer

Answer 8

What does the immune system see in a gram negative cell?

Question 9

N-acetyl muramic acid, N-acetyl glucosamine linked by glycosidic bonds, peptide crosslinking in G+

Answer 9

Components of peptidoglycan

Question 10

links 4 to 3, made up of amino acids

Answer 10

interbridges

Question 11

Mur A–> MurE require ATP and add peptides, MurF adds dipeptide, parks nucleotide at end of Mur, sugar peptide is transferred onto undecaprenyl phosphate (lipid I) –> lipid II

Answer 11

Peptidoglycan synthesis steps of assembly

Question 12

Assembly (Murs), Transport (Lipid Cycle through the intermembrane), polymerization (adding pentapeptide)–alternating NAG and NAM

Answer 12

Three phases of peptidoglycan synthesis

Question 13

cation homeostasis, trafficking ions nutrients proteins and antibiotics, regulation of autolysin – what snips and adds pieces to peptidoglycan, presentation of envelope protiens

Answer 13

function of anionic polysaccharides

Question 14

linker region covalently attached to peptidoglycan (TA) or free hydroxyl (LPS), and a highly phosphorylated polymer

Answer 14

structure of teichoic and lipteichoic acids

Question 15

alanine, glucose, or glucosamine

Answer 15

R group in P-glycerol teichoic acid

Question 16

R1 can be glucose or GlcNAc, R2/R3 may be alanine

Answer 16

R group in P-ribitol teichoic acid

Question 17

their outer membrane is impermeant to large hydrophilic molecules and prevents rapid diffusion of small hydrophobic molecules

Answer 17

Why are G- more resistant to hydrophobic antibiotics and detergents than G+

Question 18

small hydrophilic molecules through nonspecific protien channels (porins), large molecules such as vitamins and iron chelates through specialized channels

Answer 18

What crosses outer membrane and through what?

Question 19

adding sugars to Kdo-Lipid A, sugars donated from sugar nucleotide diphosphates, sugars modified after being donated

Answer 19

Core synthesis

Question 20

prototype, widespread, involves hetero- and branched-polysaccharides

Answer 20

overall WYZ dependent details

Question 21

widespread, used for non-branched polysaccharides

Answer 21

overall ABC-Transporter dependent details

Question 22

• growth is from the reducing end of the polysaccharide

- no ATP requirement

Answer 22

function of Wyz dependent o-antigen synthesis

Question 23

• requires ATP hydrolysis

- long linear polymer with undecaprenyl phosphate and terminating sugar (passed through middle assembled)

Answer 23

function of ABC transporter

Question 24

• activated sugar pushes through the membrane as it is synthesized

Answer 24

synthase dependent polysaccharide synthesis