membrane protein structure and assembly ross dalbey the ohio state university department of...
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Membrane Protein Structure and Assembly
Ross DalbeyThe Ohio State UniversityDepartment of Chemistry
Structures and architectures
• Protein-lipid interactions
• Two architectures (at least)
• TM helices
• Connecting loops and tails
• The “positive inside” rule
Biological Membrane
Heijne Nature Reviews Molecular Cell Biology 7, 909–918 (December 2006) | doi:10.1038/nrm2063
Molecular Interactions in Membrane Proteins
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
N
N
N
C
C
C
Procoat Leader Peptidase MalF
Periplasm
Cytoplasm
InnerMembrane
Dalbey (1990) TIBS 15, 253-257
Topology can be manipulated
N N
NC
Periplasm
Cytoplasm
InnerMembrane
Assembly of Membrane Proteins
Cytochrome bo oxidaseLacY permease
III+IV I IIIII+IV I II
Cyto
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
Front to Front
The X-ray Structure of the SecY complex in Methanococcus jannaschii
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
Samuelson et al., (2000) Nature, 406, 637-41
YidC is essential for cell viability
YidC depletion studies
Samuelson et al., 2000, Nature, 406, 637-641
Samuelson et al., 2000, Nature, 406, 637-641
Effect of YidC depletion on Sec-independent Membrane Insertion
Illustration of site-specific photocrosslinking
Chen et al. (2002) JBC, 277, 7670-7675
YidC and Ffh interact with Pf3 coat
N
N
+
- --
--
++
++
PMF
YidC
CC
Pf3 coat InsertionPf3 coat Insertion
YidC is a Membrane Protein Insertase for Sec-Independent
Proteins
Procoat InsertionProcoat Insertion
Dalbey and Kuhn (2004) J. Cell Biol. 166, 769
NADH-dehydro-genases Ubiquinol
Pool
CytochromeOxidasebo3
NADH NAD+ O2H2O
H+
H+
e- e- e-
H+H+H+
F0
F1
ATP synthase
Periplasm
Cytoplasm
Why is YidC essential for Bacteria?
Respiratory chain complexes in E. coli
Substrates for the YidC-only pathway
Pf3coat M13procoat F-ATPasesubunit c
N
N
N Periplasm
MscL
N
•YidC is required for membrane insertion of these substrates
•Pf3 coat can insert into proteoliposomes containing only YidC
Substrates for the YidC-Sec pathway
F1Fo-ATPasesubunit a
N
NPeriplasm
LacY
N
P1 C
C C
•YidC is required for membrane insertion of CyoA and subunit a
•YidC is required for the membrane protein folding of LacY
CyoA
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