Transcript Lecture for Ribosomal P

Translation
7mG
Initiation
Recruitment of mRNA to the ribosome
AAAAAn
7mG
Elongation
Synthesis of nacent polypeptide
nAAAAA
Termination
Release of polypeptide from the ribosome
7mG
nAAAAA
Eukaryotic Ribosome Structure
60S
Large Subunit
80S
Small Subunit
40S
Large subunit
rRNA:
Proteins:
28S, 5.8S and 5S
44 - 47
Small subunit
18S
33 - 35
P-protein Stalk of the Large Ribosomal Subunit
•Universal Feature
•Component of the
60S
28S rRNA
Active
Site of the Ribosome
•Stimulate EF2-GTPase
activity
•
P0 + (P1 + P2)2
P0: 35 kDa
P1 and P2: ~12 kDa
Characteristic P-protein
Variable N-terminus
Acidic Hinge
Conserved
C-terminus
P-protein Complexity
Bacteria
Rat
P1
Yeast
P1a
P1b
P1
L12
P2
P2a
P2b
P2
Plant Ribosomes Contain Four Distinct
12-kDa P-proteins
ESDDDMGFSLFD
ESDDDMGFSLFD
ESDEDMGFSLFD
KSDDDMGFSLFD
Variable N-terminus
Acidic
Hinge
Conserved
C-terminus
P-protein Complexity
Bacteria
Rat
Yeast
Plants
P1
P1a
P1b
P1
P1
P2
P2a
P2b
P2a
P2b
P2
P3
P3
L12
Regulatory Role of P-proteins in Translation
•Slow
Growth of Yeast P-protein Deficient Mutants
Wild type
+ P-proteins
Mutants
No P-proteins
X
Regulatory Role of P-proteins in Translation
•Ribosomes
of Actively Dividing Yeast Cells Contain More
P-proteins than Ribosomes of Cells in the Stationary Phase
Stationary Phase
log Phase
Arabidopsis: A model plant system
•Genome sequenced
•Rapid life cycle
•Easy to grow
•LOTS of seed
•Genetic “tools” available
•Large number of mutants available
"What is a weed? A plant whose virtues have not yet been discovered."
Ralph Waldo Emerson
Agrobacterium tumefaciens Infection
Plant Cell
Agrobacterium
tumefaciens
T-DNA
Chromosome
Ti plasmid
Nucleus
Chromosomal
DNA
T-DNA