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MIP 443 > Lecture 17 --Second Messengers > Flashcards

Lecture 17 --Second Messengers Flashcards

1
Q

intracellular signaling molecules that relay information perceived on the outside of cells to the target molecules inside the cell

A

secondary messengers

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2
Q

what type of molecules are the known secondary messengers?

A

multiphosphorylated nucleotides or cyclic nucleotides

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3
Q

which second messenger is involved with stringent response and other nutrient responses

A

p(pp)Gpp

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4
Q

which secondary messenger is involved in the regulation of metabolic activities and virulence mechanisms (multiple are found in a single bacterium)

A

cAMP

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5
Q

which secondary messenger is involved in cyst formation, but for the most part has little known about it

A

cGMP

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6
Q

which secondary messenger is involved in DNA damage-dependent cell cycle control and viability

A

c-di-AMP

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7
Q

which secondary messenger is involved in the regulation of biofilms as well as virulence and motility

A

c-di-GMP

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8
Q

are cyclic secondary messengers made up or mainly purines or pyrimidines and which do these include?

A

mainly purines (adenine and guanine)

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9
Q

what is produced in response to starvation – they show up as “magic spots” in the absence of amino acids, and what is this response known as

A

alarmones; stringent response

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10
Q

which secondary messengers are associated with the inhibition of rRNA synthesis and upregulation of amino acid biosynthesis during amino acid starvation

A

ppGpp and pppGpp

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11
Q

why does the stringent response involve a flat period of no growth?

A

Cells divert resources away from growth and towards the biosynthesis of amino acids

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12
Q

what fold reduction is seen in the rRNA, tRNA, and protein synthesis during stringent response?

A

10-20 fold reduction

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13
Q

SpoT is found in the stringent response. What is its role with regard to the synthesis of ppGpp

A

When amino acids are available, the hydrolase domain degrades ppGpp

When there is a lack of amino acids, acyl carrier protein binds to SpoT to activate synthesis of ppGpp

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14
Q

Does amino acid starvation result in charged or uncharged tRNA and how does this affect normal binding

A

uncharged, instead of binding to A-site of ribosome, acts as a signal for RelA to synthesize ppGpp

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15
Q

Which domain of the RelA/SpoT have catalytic abilities?

A

The n-terminal (NTD)

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16
Q

Determine strength of synthase activity and hydrolase activity for RelA and SpoT

A 
RelA = strong synthase activity, weak nonfunctional hydrolase activity
SpoT = weak synthase activity, strong hydrolase activity
17
Q

What are the two functions of the CONSERVED TGS and ACT domains in RelA and SpoT

A

TGS - binds uncharged ACP/determines synthesis/hydrolase activity in SpoT

ACT - interacts with ribosome

18
Q

What turns off/on RelA and SpoT and how does this change concentrations of ppGpp in the cell

A

RelA is associated with 1% of ribosomes = base levels of ppGpp always produced

uncharged ACP results in decreased hydrolysis activity, less degraded, more synthesized

19
Q

what type of second messengers are made up of a single phosphate nucleotide with a cyclic bond arrangement between the sugar and phosphate groups

  • are used for hormone and ion channel signaling in eukaryotes
  • allosteric effectors of DNA-binding proteins in prokaryotic cells
  • have biological significance for a range of protein - ligand interactions
A

cyclic nucleotides

20
Q

what two molecules are messengers for glucose catabolism

A

CRP/CAP and cAMP

21
Q
  • a key secondary messenger that controls catabolite repression
  • associated with kinase function in regulation of glycogen, sugar, and lipid metabolism
A

cAMP (cyclic adenosine monophosphate)

22
Q
  • A CyclicAMP Receptor Protein (CRP) homologue that can control virulence
  • reduced in virulence (mutants of adenylate cyclase)
A

virulence factor regulator

23
Q

Does CRP expression increase or decrease as pathogen depletes glucose in lungs and forms large biofilm

A

increase

24
Q

Serves as a DNA integrity scanning protein to check cell cycle checkpoints and sporulation, controls cell size and envelope stress, widely found in bacteria and a subset of archaea

A

c-di-AMP

25
Q

What produces c-di-AMP and what degrades it

A

diadenylate cyclase (DAC); phosphodiesterase

26
Q

What is DarR a receptor protein for?

A

c-di-AMP

27
Q

Why was it so difficult to discover c-di-AMP

A

It is essential, disA, dacA, and dacB mutants do not work –> shows required for normal cellular growth

28
Q

which secondary messenger acts as an effector of the cellulose synthase enzyme

A

c-di-GMP

MIP 443 (14 decks)

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