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PDBsum entry 1a8c
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References listed in PDB file
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Key reference
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Title
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Primary sequence and solution conformation of ferrocytochrome c-552 from nitrosomonas europaea.
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Authors
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R.Timkovich,
D.Bergmann,
D.M.Arciero,
A.B.Hooper.
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Ref.
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Biophys J, 1998,
75,
1964-1972.
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PubMed id
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Abstract
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Cytochrome c-552 from Nitrosomonas europaea is a 9.1-kDa monoheme protein that
is a member of the bacterial cytochrome c-551 family. The gene encoding for
c-552 has been cloned and sequenced and the primary sequence of the product
deduced. Proton resonance assignments were made for all main-chain and most
side-chain protons in the diamagnetic, reduced form by two-dimensional NMR
techniques. Distance constraints (1056) were determined from nuclear Overhauser
enhancements, and torsion angle constraints (88) were determined from scalar
coupling estimates. Solution conformations for the protein were computed by the
hybrid distance geometry-simulated annealing approach. For 20 computed
structures, the root mean squared deviation from the average position of
equivalent atoms was 0.84 A (sigma = 0.12) for backbone atoms over all residues.
Analysis by residue revealed there were three regions clearly less well defined
than the rest of the protein: the first two residues at the N-terminus, the last
two at the C-terminus, and a loop region from residues 34 to 40. Omitting these
regions from the comparison, the root mean squared deviation was 0.61 A (sigma =
0.13) for backbone atoms, 0.86 A (sigma = 0.12) for all associated heavy atoms,
and 0. 43 A (sigma = 0.17) for the heme group. The global folding of the protein
is consistent with others in the c-551 family. A deletion at the N-terminus
relative to other family members had no impact on the global folding, whereas an
insertion at residue 65 did affect the way the polypeptide packs against the
methionine-ligated side of the heme. The effects of specific substitutions will
be discussed. The structure of c-552 serves to delineate essential features of
the c-551 family.
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