March 4 Flashcards
(13 cards)
What is the preferred carbon source for yeast?
Glucose
What does Snf-1 protein stand for? What type of protein is it?
It stands for sucrose non-fermenting protein 1. It is a protein kinase
What is the rough experimental to identify colonies with mutations that prevent them from using other carbon sources than glucose?
You first grow them on glucose plate, then mutagenize them, shift the carbon source, then some will stop growing. You pick those single colonies and grow them in liquid glucose media individually, if they’re not growing because DNA pol mutation or something, then they must have something that is related to them using other carbon source. THen clone the genes
What is snf1 complexed with? What activates this complex?
Snf1 is with Snf4 and snf1 interacting protein (SIP). So heterotrimer. If the serine on the activation loop of snf1 is PO4’d, then it is active and cell can use other carbon sources.
What happens to ATP and ADP/AMP levels as yeast is glucose starved?
The ATP levels go down, so ADP and AMP go up
What metabolite is needed for yeast to make nucleotides, AA’s, pentose phosphate pathway to make NADPH?
Need Glucose 6 Phosphate (G6P)
How can yeast utilize lactate and ethanol, how do they enter TCA cycle? What do they become before can leave TCA cycle and become what?
Lactate will become pyruvate, then around cycle becomes oxaloacetate. EtOH will be converted, then become acetyl-CoA, also become oxaloacetate. Oxaloacetate will become aspartate but also be comverted to phosphoenolpyruvate, so now can go reverse glycolysis and get to the glucose 6 phosphate.
What is the irreversible step in glycolysis?
It is the last step, it is phosphoenolpyruvate to pyruvate
What is problem with TCA cycle when have no glucose, what cycle do instead, what steps are different?
TCA cycle has 2 carbon molecules left each cycle, so your metabolite pools get smaller, so if lactate (carbons) or ethanol (2 carbons), it is not as good as pyruvate (3 carbons). The glyoxylate cycle works at same time in parallel, it turns isocitrate straight to succinate or acetyl-CoA, skips the a-ketoglutarate and losing hte CO2 and producing NADH. Both aceytl coa or succinate eventually become oxaloacetate that is needed to get the G6P. Glycosylate cycle produces less NADH so less ATP, but still overall better option
What is it called when yeast switch from using glucose to ethanol?
Diauxic shift
Snf1 is in yeast, but there is homolog in humans called something else. What is it called and what is it activated by? How ADP play role in this?
Loss of glucose causes a kinase to PO4 and activate AMP kinase (Snf1) on activation loop. ADP binding to Snf1 can prevent its dephosphorylation, so when cell has more energy, it has less ADP, so Snf1 can be deactivated (dephosphorylated) and cwll can use glucose again.
There are 3 kinases that phosphorylate Snf1. Is there difference if knock out all 3 of them or just knock out Snf1?
No, each kinase kind of activate Snf1, so if get rid of 1, other 2 will still activate it. So only way to get same phenotype as knocking out Snf1 is to knock out all 3 kinases
