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The article discusses the biochemical and physiological implications of butane monooxygenase activity in pseudomonas butanovora. Bacterial monooxygenase enzymes are broadly studied for its potential to help degrade environmental pollutants. It also serves as a biocatalysts for the creation of important chemicals for industrial purposes. Pseudomonas Butanovora cultivates with butane through the oxidation of butane to 1- butanol. This is done through a soluble butane monooxygenase. A supposed model is presented that tries to explain propionate- dependent inactivation with the butane monooxygenase when applied to the soluble methane monooxygenase.

The physiological consequences of trichloroethylene (TCE) transformation by three butane oxidizers were examined. Pseudomonas butanovora, Mycobacterium vaccae, and Nocardioides sp. CF8 utilize distinctly different butane monooxygenases (BMOs) to initiate degradation of the recalcitrant TCE molecule. Although the primary toxic event resulting from TCE cometabolism by these three strains was loss of BMO activity, species differences were observed. P. butanovora and Nocardioides sp. CF8 maintained only 4% residual BMO activity following exposure to 165 μM TCE for 90 min and 180 min, respectively. In contrast, M. vaccae maintained 34% residual activity even after exposure to 165 μM TCE for 300 min. Culture viability was reduced 83% in P. butanovora, but was unaffected in the other two species. Transformation of 530 nmol of TCE by P. butanovora (1.0 mg total protein) did not affect the viability of BMO-deficient P. butanovora cells, whereas transformation of 482 nmol of TCE by toluene-grown Burkholderia cepacia G4 caused 87% of BMO-deficient P. butanovora cells to lose viability. Together, these results contrast with those previously reported for other bacteria carrying out TCE cometabolism and demonstrate the range of cellular toxicities associated with TCE cometabolism. [ABSTRACT FROM AUTHOR]

Butane monooxygenase (BMO) from Pseudomonas butanovora has high homology to soluble methane monooxygenase (sMMO), and both oxidize a wide range of hydrocarbons; yet previous studies have not demonstrated methane oxidation by BMO. Studies to understand the basis for this difference were initiated by making single-amino-acid substitutions in the hydroxylase α subunit of butane monooxygenase (BMOH-α) in P. butanovora. Residues likely to be within hydrophobic cavities, adjacent to the diiron center, and on the surface of BMOH-α were altered to the corresponding residues from the α subunit of sMMO. In vivo studies of five site-directed mutants were carried out to initiate mechanistic investigations of BMO. Growth rates of mutant strains G113N and L279F on butane were dramatically slower than the rate seen with the control P. butanovora wild-type strain (Rev WT). The specific activities of BMO in these strains were sevenfold lower than those of Rev WT. Strains G113N and L279F also showed 277- and 5.5-fold increases in the ratio of the rates of 2-butanol production to 1-butanol production compared to Rev WT. Propane oxidation by strain G113N was exclusively subterminal and led to accumulation of acetone, which P. butanovora could not further metabolize. Methane oxidation was measurable for all strains, although accumulation of 23 µM methanol led to complete inhibition of methane oxidation in strain Rev WT. In contrast, methane oxidation by strain G113N was not completely inhibited until the methanol concentration reached 83 µM. The structural significance of the results obtained in this study is discussed using a three-dimensional model of BMOH-α. [ABSTRACT FROM AUTHOR]