CiteULike: neils's Pettigrew

The cytochromes c-550 of Paracoccus denitrificans and Thiosphaera pantotropha: a need for re-evaluation of the history of Paracoccus cultures

Celia Goodhew — 2008-05-11T09:37:08-00:00

FEMS Microbiology Letters, Vol. 137, No. 1. (1996), pp. 95-101.

Abstract The c-type cytochrome and protein profiles were compared for a number of cultures of Paracoccus denitrificans obtained from a range of culture collections. The cultures fell into two groups corresponding to the two original isolates of this bacterial species. One group, which included NCIMB 8944, ATCC 13543, ATCC 17741, ATCC 19367, Pd 1222 and DSM 413, were similar or identical to LMD 22.21. The second group, including DSM 65 and LMG 4218, were similar or identical to LMD 52.44. These groupings were not compatible with the recorded history of culture deposition. Mass spectrometry and amino acid sequence comparisons showed that the cytochrome c-550 of the LMD 52.44 culture group differed by 16% from that of the LMD 22.21 group, and yet was only 1% different from the cytochrome c-550 of Thiosphaera pantotropha. These results suggest that consideration should be given to creation of a new species of Paracoccus pantotropha, which would include Thiosphaera pantotropha and Paracoccus denitrificans LMD 52.44.

Structural characterization of Paracoccus denitrificans cytochrome c peroxidase and assignment of the low and high potential heme sites.

W Hu — 2008-05-11T09:18:21-00:00

Biochemistry, Vol. 36, No. 26. (1 July 1997), pp. 7958-7966.

The amino acid sequence of the diheme cytochrome c peroxidase from Paracoccus denitrificans has been determined as the result of sequence analysis of peptides generated by chemical and enzymatic cleavages of the apoprotein. The sequence shows 60% similarity to the cytochrome c peroxidase from Pseudomonas aeruginosa, 39% similarity to an open reading frame encoding a putative triheme c-type cytochrome in Escherichia coli, and remote similarity to the MauG proteins from two methylotrophic bacteria. It is proposed, on the basis of the pattern of conserved residues in the sequences, that a change in iron coordination in the N-terminal heme domain may accompany reduction to the active mixed valence state, a change which may be accompanied by conformational adjustments in the highly conserved interface between the N- and C-terminal domains. These conformational adjustments may also lead to the appearance of a second Ca2+ binding site in the mixed valence enzyme. The exposed edge of the heme in the C-terminal domain is surrounded by several different patterns of charged residues in the Paracoccus and Pseudomonas enzymes, and this is consistent with the interaction of the former with the highly positively charged front face of the donor cytochrome c-550.

Calcium-Dependent Heme Structure in the Reduced Forms of the Bacterial Cytochrome c Peroxidase from Paracoccus pantotrophus

Sofia Pauleta — 2008-04-29T08:20:34-00:00

Biochemistry (29 April 2008)

Abstract: This work reports for the first time a resonance Raman study of the mixed-valence and fully reduced forms of Paracoccus pantotrophus bacterial cytochrome c peroxidase. The spectra of the active mixed-valence enzyme show changes in the structure of the ferric peroxidatic heme compared to the fully oxidized enzyme; these differences are observed upon reduction of the electron-transferring heme and upon full occupancy of the calcium site. For the mixed-valence form in the absence of Ca2+, the peroxidatic heme is six-coordinate and low-spin on the basis of the frequencies of the structure-sensitive Raman lines: the enzyme is inactive. With added Ca2+, the peroxidatic heme is five-coordinate high-spin and active. The calcium-dependent spectral differences indicate little change in the conformation of the ferrous electron-transferring heme, but substantial changes in the conformation of the ferric peroxidatic heme. Structural changes associated with Ca2+ binding are indicated by spectral differences in the structure-sensitive marker lines, the out-of-plane low-frequency macrocyclic modes, and the vibrations associated with the heme substituents of that heme. The Ca2+-dependent appearance of a strong ³15 saddling-symmetry mode for the mixed-valence form is consistent with a strong saddling deformation in the active peroxidatic heme, a feature seen in the Raman spectra of other peroxidases. For the fully reduced form in the presence of Ca2+, the resonance Raman spectra show that the peroxidatic heme remains high-spin.