Amaranth Flaveria

1
C4 dicots
Amaranth Flaveria
2
Ribulose 1,5-Bisphosphate Carboxylase (Rubisco)
Reactions
CO2 H2O
RuBP (5C)
2 X 3-P-Glycerate (3C) 2 H
Rubisco
O2 H2O
1 X 3-P-Glycerate (3C) 2H 1 X
2-P-Glycolate (2C)
RuBP (5C)
Rubisco
Located in chloroplasts 6 Large Subunits
(LSU), 55 kDa. rbcL gene Encoded on chloroplast
genome Contains substrate (CO2 and O2) binding
site. 6 Small Subunits (SSU), 12-18 kDa.
RbcS gene Encoded in nuclear
genome as gene family Synthesized as precursor,
20 Kda, with plastid transit sequence Transported
to chloroplasts Possibly for regulation and
assembly
3
How are rbcL and RbcS genes encoding
Rubisco regulated in C4 plants? Regulated by
leaf development? Regulated by
light? Transcriptional? Post-transcriptional?
4
(No Transcript)
5
A
B
C
6
(No Transcript)
7
A
B
In vivo protein synthesis and mRNA levels
Polysome analysis RbcS and rbcL mRNAs are
associated with polysomes in L and in D5hr L
plants RbcS and rbcL mRNAs are not associated
with polysomes in D plants Regulation in
response to light occurs at the level of
translation initiation
8
Rubisco rbcL and RbcS genes are regulated
post-transcriptionally in C4 plants Rubisco
gene expression in C4 leaves is influenced
by Light Leaf development Photosynthesis Gene
s encoding other C4 enzymes show independent
patterns of regulation
9
What proteins regulate translation or stability
of the Rubisco mRNAs, and what cis-acting
sequences are recognized by these
proteins? Two approaches Biochemical
analysis (search for mRNA binding
proteins) Transgenic C4 plants (Search for
cis-acting regulatory sequences)
10
McCormac et al., JBC 276, 2001
11
(No Transcript)
12
(No Transcript)
13
(No Transcript)
14
(No Transcript)
15
pSK to generate transcripts for in vitro
translation (T3) pBI221 for Biolistic (gene
gun) transient expression (CaMV) pGA482 for
expression in stably transformed C4 plants (CaMV)
16
(No Transcript)
17
(No Transcript)
18
(No Transcript)
19
(No Transcript)
20
Graduate Students Jingliang Wang Ping Xu Amy
Swec Joe Boinski John Long Amy Corey Jianxin
Wang Hanz Litz Vince Ramsperger Sabrina
Picinic Francois Faure
Technicians Sejal Patel Xiaowen Jang
Collaborators John Carr (Cambridge) Bill Taylor
(Canberra) Li Ping Lin (Beijing) V. James
Hernandez (UB) Derek Taylor (UB) Jeremy Bruenn
(UB) Mary Bisson (UB)
Funding NSF Biochemistry of gene expression
International programs USDA Photosynthesis
Plant genetic mechanisms
Postdocs Minesh Patel Robert Givens Mei-Hui
Lin Dennis McCormac
Undergraduates Jackson Buss Elizabeth
Herric Theresa Flood Francois Faure Kwan Lau Eric
Rydzik Paul Nordone Marina Boruk Jeff
Burkwitz Janet Lam Jay Friedman Melinda
Bauman Renata Mazzei Diane Watkins Matt
Bernhard Peter Depowski Curtis Erickson