Nitriles (R-CN) contain a cyano functional group and they are very toxic. We have studied microbial degradation of nitriles. Their microbial degradation proceeds through two enzymatic pathways; nitrile hydratase catalyzes hydration of nitrile to amide followed by its conversion to acid plus ammonia by amidase, whereas nitrilase catalyzes hydrolysis of nitrile to acid plus ammonia. We have characterized these enzymes and their genes from several microorganisms. Particularly, we have focused on industrial strains such as Rhodococcus rhodochrous J1 and Pseudomonas chlororaphis B23.
Here, I would like to discuss about nitrile studies for these industrial strains from the following aspects: (i) Screening of nitrile-degrading microorganisms; (ii) investigation of culture condition; (iii) characterization of the enzymes involved in nitrile metabolism; (iv) diverse nitrile metabolism; (v) gene organization for nitrile-synthetic and degradation pathways linked with acid-utilization pathway; (vi) posttranslational modification of the enzyme; (vii) heme-containing enzyme synthesizing a cyano functional group; (viii) investigation of enzyme substrate specificity.
By changing nitrile substrates, various kinds of nitrile-degrading strains can be obtained. Information of enzyme characteristics and genetic analysis for nitrile metabolism are essential for industrial manufacture of useful compounds.
Major publications:
1) Biochemistry, 31, 9000 [1992]; 4) Nature Biotech, 16, 733 [1998]; 5) JBC, 278, 29600 [2003]; 6) JBC,279, 47619 [2004]; 7) PNAS, 101, 14031 [2004]; 8) JBC, 280, 8660 [2005]; 9) PNAS, 103, 564 [2006]; 10) PNAS,105, 14849 [2008]; 11) JBC, 283, 11312 [2008]; 12) JBC, 284, 14930 [2009]; 13) Biochem., 49, 9638 [2010]; 14) PNAS, 110, 2810 [2013]