Download Membrane protein structure and assembly

Membrane Protein Structure and
Assembly
Ross Dalbey
The Ohio State University
Department of Chemistry
Structures and architectures
•
•
•
•
•
Protein-lipid interactions
Two architectures (at least)
TM helices
Connecting loops and tails
The “positive inside” rule
Biological Membrane
Molecular Interactions in Membrane Proteins
Heijne Nature Reviews Molecular Cell Biology 7, 909–918 (December 2006) | doi:10.1038/nrm2063
Only two basic structures
TM helix lengths are typically 20-30
residues
(Bowie, JMB 272: 780)
Loops tend to be short
(Tusnady & Simon, JMB 283:488)
The “positive inside” rule
C
N
Periplasm
Inner
Membrane
N
C
Cytoplasm
C
N
Procoat
Leader Peptidase
Dalbey (1990) TIBS 15, 253-257
MalF
Topology can be manipulated
C
N
Periplasm
Inner
Membrane
N
N
Cytoplasm
Assembly of Membrane Proteins
Cyto
III+IV
I
II
Cytochrome bo oxidase
LacY permease
F1Fo ATPase
Many membranes in a eukaryotic cell
Membrane translocation and insertion devices in bacteria and in the
endoplasmic reticulum
The machinery that is involved in
membrane protein insertion in E. coli
Xie and Dalbey (2008)
Nature Reviews Micro 6, 235
The X-ray Structure of the SecY
complex in Methanococcus jannaschii
Front to Front
Van den berg et al., 2004, Nature 427 36-44
Van den Berg et al (2004) Nature 427, 36
Different stages of translocation of a secretory
protein
Recognition of a transmembrane
helix by the Sec61 translocon
Hessa et al (2005) Nature 433, 377
Evolutionarily conserved
YidC Family Members
Stuart and Neupert (2000) Nature (News and Views) 406, 575
Jim Samuelson
YidC is essential for cell viability
Samuelson et al., (2000) Nature, 406, 637-41
YidC depletion studies
Samuelson et al., 2000, Nature, 406, 637-641
Effect of YidC depletion on Secindependent Membrane Insertion
Samuelson et al., 2000, Nature, 406, 637-641
Illustration of site-specific
photocrosslinking
YidC and Ffh interact with Pf3 coat
Chen et al. (2002) JBC, 277, 7670-7675
YidC is a Membrane Protein
Insertase for Sec-Independent
Proteins
YidC
-
+
N
PMF
Procoat Insertion
N-
-
+
+
C
Pf3 coat Insertion
Dalbey and Kuhn (2004) J. Cell Biol. 166, 769
+
+
C
Why is YidC essential for Bacteria?
H+
H+
H+
H+
Cytochrome
NADHOxidase
dehydroUbiquinol bo3
genases
Pool
ee
e-
NADH NAD+
H+
O2
Periplasm
F0
Cytoplasm
H2O
F1
ATP synthase
Respiratory chain complexes in E. coli
Substrates for the YidC-only pathway
N
N
N
Pf3coat
M13procoat
Periplasm
N
F-ATPase
subunit c
MscL
•YidC is required for membrane insertion of these substrates
•Pf3 coat can insert into proteoliposomes containing only YidC
Substrates for the YidC-Sec pathway
P1
C
N
Periplasm
C
N
CyoA
F1Fo-ATPase
subunit a
C
N
LacY
•YidC is required for membrane insertion of CyoA and subunit a
•YidC is required for the membrane protein folding of LacY
YidC functions in the integration of TS into
the membrane
Xie and Dalbey (2008) Nature Reviews Micro 6, 235
YidC functions in the folding of Lac
permease
Nagamori et al. (2004) J. Cell Biol. 165, 53
Assembly of cytochrome bo oxidase
Dalbey et al (2011) Ann Rev Biochem, in press.
Assembly of F1Fo ATP synthase
Dalbey et al (2011) Ann Rev Biochem, in press
Conclusion
• α-helices and β-sheets are the basic
membrane-spanning regions
• Positively charged residues control the
membrane protein topology
• Sec translocase and YidC insertase are
the devices used to insert proteins
• The bacterial YidC functions as a
membrane chaperone and assembly
factor