Achromobacter cycloclastes nitrite reductase

Iwasaki, N., Noji, S., and Shidara, S. (1975). Achromobacter cycloclastes nitrite reductase. The function of copper, amino acid composition, and ESR spectra. J. Biochem. (Tokyo) 78, 355-361. 

Libby, E., and Averill, B. A. (1992). Evidence that the type 2 copper centers are the site of nitrite reduction by Achromobacter cycloclastes nitrite reductase. Biochem. Biophys. Res. Commun. 187, 1529-1535. 

Figure 3 Electronic absorption (A) and magnetic circular dichroism (B) spectra of the Type 1 Cu site of Achromobacter cycloclastes nitrite reductase (a) and spinach plastocyanin (b). Absorption data were obtained at 120 K for nitrite reductase and at 25 K for plastocyanin. MCD spectra were obtained at 4.2 K. Gaussian resolution of bands in the absorption spectra is based on a simultaneous linear least-squares fit of Abs, MCD, and CD data for each. MCD data from 5000 to 8000 cm have been multiplied by a factor of 5. (Reprinted with permission from Ref. 22. 1996 American Chemical Society)...

The blue protein from A. faecalis strain S-6, which was isolated as a requirement for transferring electrons to a copper-containing nitrite reductase, has since been shown to have sequence homology with proteins arbitrarily designated pseudoazurin by Ambler and Tobari (1985), from Achromobacter cycloclastes and from Pseudomonas AMI. [Pseudomonas AMI also produces amicyanin, which is the recipient of electrons from methylamine dehydrogenase, (see below)]. In A. cycloclastes reduced pseudoazurin donates electrons to a copper nitrite reductase (Liu et ai, 1986), as it does in A. faecalis. Ambler and Tobari (1985)... 

Hulse, C. L., and Averill, B. A. (1989). Evidence for a copper-nitrosyl intermediate in denitrification by the copper-containing nitrite reductase of Achromobacter cycloclastes. J. Am. Chem. Soc. Ill, 2322-2323. 

The crystal structure of nitrite reductase (NiR) from Achromobacter cycloclastes was recently reported by Godden et al. (46). The protein contains both a type I and a type II copper site. The type I center has a distorted tetrahedral structure typical of type I copper, whereas the... 

Figure 1. Schematic representation of the copper sites in nitrite reductase from Achromobacter cycloclastes (17).

Fig. 8. (a) Drawing of the trimer of nitrite reductase from Achromobacter cycloclastes. (b) Drawing of the interface between domain 1 (subunit A) and domain 2 of the adjacent symmetry-related molecule (subunit C) of nitrite reductase from A. cycloclastes. (c) Drawing of domain 1 and 3 of ascorbate oxidase. The type-1 copper is in domain 3 and the trinuclear copper center is between domain 1 and domain 3. The domains have an orientation similar to that of the corresponding domains of the nitrite reductase shown in b. The figure was produced by the RIBBON Program (S7). 

Iwasaki H, Matsubara T (1972) A nitrite reductase from Achromobacter cycloclastes. J Biochem 71 645-652... 

Until now, pseudoazurin has only been found in bacteria, e.g., in the denitrifying bacteria Alcaligenes faecalis and Achromobacter cycloclastes. It is the electron donor of the green copper-protein nitrite reductase which catalyses the reduction of nitrite (NO2) to nitrogen monoxide (NO) [86-89]. The physiological electron donor of pseudoazurin is as yet unknown [70]. Pseudoazurin has a molecular mass of approximately 13.5 kD and a chain length of about 123 amino acid residues [88]. The additional amino acids, as compared with plastocyanin, form the C-terminal end of the protein (Fig. 14). The pseudoazurins have redox potentials of about 230 mV [90,91]. 

Most proteins with type 1 copper centers are blue, although the nitrite reductases from Achromobacter cycloclastes, Alcaligenes faecalis, and Pseudomonas aureofaciens, are green [26,27]. This is probably caused by a distortion of the type 1 copper center, although the interrelation of distortion and absorption properties of the copper centers have not yet been clarified [27]. 

A denitrifying nitrite reductase from Achromobacter cycloclastes and Ps. denitrificans is a copper protein, containing two moles copper per mole of protein (molecular weight 69 000). This reduces nitrite to nitrogen monoxide. 

Nitrite Reductase Achromobacter cycloclastes 458nm = 2200 Esssmn 1.800 1.22 rhombic (73) 2.56 278,279... 

Nitrite reduction to nitric oxide is catalyzed by dissimilatory nitrite reductase. The enzymes purified from Alcaligenes faecalis (Iwasaki and Matsub-ara, 1971), Pseudomonas aeruginosa (Walker and Nicholas, 1961), andMj-crococcus denitrificans (Newton, 1969) have been shown to contain c d-type cytochrome. The nitrite reductase from Achromobacter cycloclastes does not... 

Adman ET, Godden JW, Turley S (1995) The structure of copper-nitrite reductase from achromobacter cycloclastes at five pH values, with NO-2 bound and with type 11 copper depleted. J Biol Chem 270 27458-27474... 

The copper-containing nitrite reductases (Cu NiR s) also contain two distinct types of chromophore. The best characterized is that from Achromobacter cycloclastes, for which a 2.3 A resolution X-ray structure has been reported (12). The enzyme consists of an a3 trimer of 34.5 kDa subunits, each of which contains two copper atoms in distinct sites. One is an... 

Figure 8. Schematic drawing showing the structure and arrangement of copper centers in the Cu-containing nitrite reductase from Achromobacter cycloclastes.

Jackson, M. A., J. M. Tiedje, and B. A. Averill. 1992. Evidence for an NO-rebound mechanism for production of N2O from nitrite by the copper-containing nitrite reductase from Achromobacter cycloclastes. FEBS Lett. 291 41-44. 

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