Metal Stress

Question 1

What are metalloenzymes

Answer 1

Essential metals are cofactors for catalytic acitity and occur in six enzyme comission classes such as oxidoreductases transferaases hydrolase lyases isomerase and ligase

Question 2

What is the most prelevant metal to least

Answer 2

Mg Zn Fe and Mn

Question 3

What is toxicity caused by

Answer 3

Interacation with SH and other functional groups displacement of essential metal cofactors and binding with certain protiens

Question 4

What are common toxic effects

Answer 4

Carcinogenicity, Immune system impariment, Neurotoxicity, impariment of kidney, respiratory system

Question 5

What is a structural motifi

Answer 5

Particular combination of two or more secondary structures that form a distinc three-dimensional structure when it apperas in mutiple protiens

Question 6

What is zinc fingers composed of

Answer 6

Two antiparallel B strands with two cys followed by an a helix with two histindines
Zinc ion is coordinated by four amino acid residuces that results in the finer shapre the stabilzation of protien doamin (three secondary structure in zinc ion

Question 7

What is the C4 zinc finger

Answer 7

Four conserved cysteines in contact with the Zn ion which is less common

Question 8

Where does the recognition between the zinc finger and DNA occur

Answer 8

In the major groove the protien wraps around the DNA double helix

Question 9

Which finger does not interacts with DNA

Answer 9

Finger one

Question 10

What does the cell activate with heavy metal load

Answer 10

Metal stress response pathway associated with metal regulatory transcripton factor 1 which binds to MREs enahnces metallothiones and metal transporters

Question 11

What are the 5 different functional domains of MTF-1

Answer 11

Dna binding domain, siz C2H2 zinc fingers
Nuclear import signal (NIS) domain
Nuclear export signal (NES)
Three transactivation domains
Homodimerization domain

Question 12

What does activation of MTF-1 need

Answer 12

Loading with zinc, dimerization and post-translational modification by phosphorylation

Question 13

What is happening under normal conditions to MTF-1

Answer 13

It is shuttling between the cytoplasm and nucleus which is mediated by interacation of MTF-1 with Crm1 mediated nuclear export of protiens taht carry a leucine rich NES

Question 14

How is MTF-1 activated

Answer 14

Directly or indircetly by zinc released from protiens called metallothionens upon competive heavy metal load or oxidative stress

Question 15

What is essential is MTF-1

Answer 15

All 6 zinc finger are lodaded with zin and phosphorylation

Question 16

What happens after zinc binds

Answer 16

Dimerization and phosphorylation MTF1 shuttles to nucleus where it binds to MRE which is important for maintain metal homeostasis and detoxication of heavy metals

Question 17

What else can MTF-1 help with

Answer 17

Against hypoxia hyperthermia and oxidative stress

Question 18

What was the experiment with subcellular distribution

Answer 18

Kidney cells were transfected with VSV tagged MTF-1 and fluro untreated cells have mostly cytoplasmic localization of MTF-1 while the transcrption factor moves to the nucleus in cells treated with heavy metal

Question 19

What does leptomycin B do

Answer 19

Can be stimilated by this drug which inihibits NES binding site of the nuclear export protien CRM1 induces nuclear accumulation of MTF-1 without affectin nuclear import

Question 20

What plays a role in heat shock and other stress conditons

Answer 20

MTF-1 plays a role in regulating mutiple cellular stress response

Question 21

What genes are important

Answer 21

Ones that are induced by MTF-1 and are required for maintatin metal homeostasis and detoxification of heavy metals are genes encoding meallothiones

Question 22

What are metallothioneins

Answer 22

Cystenine-rich, low molecular weight intracellular metal binding protiens

Question 23

What is the structure of metallothioneins

how many mental or atom

Answer 23

Consist of two domains alpha and beta which can bind 4 or 3 atoms of metal ions

Question 24

What is the binding affinity

Answer 24

Zn < Cd< Cu<Ag = Hg =Bi

Question 25

What does binding affinity mean

Answer 25

Cd will replace zn which will be avialble to load and activate MTF-1 which is the detoxication of non-essential metals such as cadium and the regulation of intracellular concentration of essentials metals such as Zn and Cu