Bacillus subtilis, electron

The growth of Bacillus subtilis may take place under a variety of conditions (a) aerobic conditions, (b) using nitrate as electron acceptor, and (c) fermentative conditions with glucose provided pyruvate is available as an electron acceptor since the organism lacks pyruvate formate hydrogen lyase (Nakano and Zuber 1998). 

FIGURE 24-34 Structure of SMC proteins, (a) The five domains of the SMC primary structure. N and C denoted the amino-terminal and carboxyl-terminal domains, respectively, (b) Each polypeptide is folded so that the two coiled-coil domains wrap around each other and the N and C domains come together to form a complete ATP-binding site. Two of these domains are linked at the hinge region to form the dimeric V-shaped molecule, (c) Electron micrograph of SMC proteins from Bacillus subtilis. 

The simpler cytochrome bc] complexes of bacteria such as E. coli,102 Paracoccus dentrificans,116 and the photosynthetic Rhodobacter capsulatus117 all appear to function in a manner similar to that of the large mitochondrial complex. The bc] complex of Bacillus subtilis oxidizes reduced menaquinone (Fig. 15-24) rather than ubiquinol.118 In chloroplasts of green plants photochemically reduced plastoquinone is oxidized by a similar complex of cytochrome b, c-type cytochrome /, and a Rieske Fe-S protein.119 120a This cytochrome b6f complex delivers electrons to the copper protein plastocyanin (Fig. 23-18). 

Cua centers exist in two redox states [Cu(II)Cu(I)] and [Cu(I)Cu(I)]. The oxidized species is a fully delocalized mixed-valence pair (formally two Cu+ 1.5 ions), as revealed by EPR spectroscopy (Kroneck et al., 1988, 1990). Despite the similar coordination geometry around copper, these systems display sharper NMR lines than do the BCP due to a shorter electron relaxation time of the paramagnetic center (wlO "s) (dementi and Luchinat, 1998). NMR studies are available for the native Cua centers from the soluble fragments of the The. thermophilus, Paracoc-cus denitrificans, Paracoccus versutus, and Bacillus subtilis oxidases (Bertini et al., 1996 Dennison et al., 1995 Luchinat et al., 1997 Salgado et al., 1998a) and Pseudomonas stutzeri N2O reductase (Holz et al., 1999), as well as for engineered Cua sites in amicyanin (Dennison et al., 1997) and Escherichia coli quinol oxidase (Kolczak et al., 1999). 

The rate with the quinone is less than 1% of the rate with TMPD so that it would be interesting to determine whether the in-vivo rate of quinone turnover during succinate oxidation is consistent with the operation of the electron transport system. Although the Sulfolobus enzyme is composed of four subunits, there is no evidence that all are associated with the enzyme other than that they copurify with enzyme activity. The succinate dehydrogenase from eucarya and bacteria have two subunits whose M, are approximately 70000 and 28 000 [112]. They appear to be analogous to the M, 66000 and 31 000 subunits from the Sulfolobus succinic dehydrogenase. The M, 66 000 subunit from Sulfolobus is catalytically active by itself, and like the Mr 70000 subunit contains covalently-bound FAD. Antisera against the Mr 66000 Sulfolobus subunit cross-reacts with an Mr 67 000 constituent in membranes from T. acidophilum, S. solfataricus, beef-heart submitochondrial particles, and Bacillus subtilis. 

S, (2002) Three-dimensional structure by cryo-electron microscopy of YvcC, an homodimeric ATP-binding cassette transporter from Bacillus subtilis. Journal of Molecular Biology, 315 (5), 1075-1085. 

G.A. Reid, C. von Wachenfeldt, and S.K. Chapman (2003). Expression, purification and characterisation of a Bacillus subtilis ferredoxin A potential electron transfer donor to cytochrome P450 Biol. J. Inorg. Biochem. 93, 92-99. 

The authors wish to thank Mr. M. Veenhuis for supplying us with the electron micrograph of Bacillus subtilis and Mrs. M.Th. Broens-Erenstein and Mrs. M. Eras for their help in the preparation of this manuscript. 

Methylamylose and 6-deoxyamylose have been studied as substrates for the crystalline liquefying amylase of Bacillus subtilis. The oligosaccharides obtained from the enzyme digests were separated by paper chromatography and some of the fractions identified after acetylation by electron-impact m.s. Neither... 

Aerobic bacteria (e.g., Paracoccus denitrificans and Bacillus subtilis) grow by oxidative phosphorylation driven by Reaction (2) where the sulfur in Reaction (1) is replaced by O2 [3]. The two reactions differ by the amount of protons apparently translocated pa- electron transported from H2 to the acceptor substrate (H /e ratio, nn+/ne). The H /e ratio is estimated to be 0.5 for Reaction (1) and 4 for Reaction (2). These numbers were calculated from the redox potentials of the substrates (Table 1 [4-6]) according to Eq. (3) with Ap = 0.17 V and assuming... 

More recently, flavin-dependent nicotinamide oxidases, such as YcnD from Bacillus subtilis [754] or an enzyme from Lactobacillus sanfranciscensis [755] were employed for the oxidation of nicotinamide cofactors at the expense of molecular oxygen producing H2O2 or (more advantageous) H2O via a two- or four-electron transfer reaction, respectively [756-758]. Hydrogen peroxide can be destroyed by addition of catalase and in general, both NADH and NADPH are accepted about equally well. 

Brunei A, Wilson A, Heniy L, Dorlet P, Santolini J (2011) The proximal hydrogen bond network modulates Bacillus subtilis nitric-oxide synthase electronic and structural properties. J Biol Chem 286 11997-12005... 

Iron-sulfur clusters are versatile electron transfer cofactors, which are ubiquitous in many metalloenzymes. In the Bacillus subtilis, redox regulator (Fnr) that controls genes of the anaerobic metabolism in response to low oxygen tension, an unusual structure for the oxygen-sensing [4Fe-4S] " cluster was detected by a combination of genetic experiments with UV-visible and Mossbauer spectroscopy [79]. Asp-141 was identified as the fourth iron-sulfur cluster ligand besides three Cys residues. 

Levansucrases.—The levansucrase from Bacillus subtilis has an average molecular weight of 5.4 x 10. Estimates of the size and shape of the molecule were comparable with those obtained by electron microscopy. 

The relative contributions of the direct Cu-Cu bond and the superexchange interactions to the Cua electronic structure have been evaluated via comparative studies on the Cua sites from Bacillus subtilis CcO, engineered azurin, and ami-cyanin vs. a mixed-valence model complex by Tolman and coworkers [69,73]. The model complex has two thiolate bridges and complete electron delocalization, evidenced by the characteristic EPR spectrum with a seven-line hyperfine splitting pattern (g gy, = 2.204, 2.046, 2.010, and = 35 x 10 cm , = 51 x 10 ... 

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