Investigation of the crystal structure of cytochrome ba 3 oxidase
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Transcript of Investigation of the crystal structure of cytochrome ba 3 oxidase
Investigation of the crystal structure of cytochrome ba3 oxidase
By Caroline Christian
Based on the paper by Soulimane, T., et all “Structure and mechanism of the aberrant ba3-cytochrome c
oxidase from Thermus thermophilus” EMBO Journal, 19 (1766-1776), 2000.
NADHDehydrogenase
Succinate dehydrogenase
bc1 complex
Cytochrome oxidase
ATP synthase
NADHNAD+
e-
SuccinateFumarate
e-
Quinol pool
O2
H2O
e-
e-
cyt c
e-e-
e-
e-
H+H+ H+
H+
ADP + Pi ATP
Respiratory chain
Out
In
Complex I Complex II Complex III Complex IV
Three different types of heme-copper oxidases
Out
Type B - ba3 oxidase
Type C - cbb3 oxidase
Type A(mitochondrial
aa3 oxidase)
I I
c c cb b3a a3 b a3
In
II II III II I
= Copper atom
= heme molecule (Iron atom)
Outside P side
Inside N side
Cytochrome ba3 oxidase crystal structure3 subunits- Subunit I, II and IIa
Subunit I – 13 alpha helixes
Subunit II – 1 alpha helix, 8 beta sheets
Subunit IIa – 1 alpha helix
Critical residues needed for function of the heme-copper oxidasesK and D channels
X-ray crystal structure of type-A oxidase (Rhodobacter sphaeroides numbering)
Residues are the K channel residues posed in the paper
Tyr 237*Ser 309Thr 312*Tyr 244Tyr 248*Ser 261*Glu 516Asp 517*= conservation
Conservation in all 14 complete type B oxidases sequences
Residues are the D-channel residues posed in paper – Top view
Three pores in the protein, two are blocked by each heme, one is blocked by D-channel.
Residues are the D-channel residues posed in paper – Side view
Glu 17Thr 21Gln 82Gln 86Ser 109Ser 153Thr 156Ser 197Thr 231Ile 235No conservation
Critical residues needed for function of the heme-copper oxidasesK and D channels
X-ray crystal structure of type-A oxidase (Rhodobacter sphaeroides numbering)
Ile 235 replaces Glu 286 (R. sphaeroides type A) at the top of the D-channel?
Ile 235
Ile 235 with all residues within 4 Angstroms of it
There are some other residues within 4 angstroms of Ile 235 that could be playing same role-
Trp 193*Thr 231Pro 234Val 236*Phe 238*Trp 239**= compete conservation