If an enzyme name is shown in bold, there is experimental evidence for this enzymatic activity.
Locations of Mapped Genes:
Synonyms: cyanate catabolism
|Superclasses:||Degradation/Utilization/Assimilation → Inorganic Nutrients Metabolism → Nitrogen Compounds Metabolism|
Cyanate can occur inside the cell as a result of nonenzymatic decomposition of carbamoyl phosphate, and in the environment due to dissociation of urea and photooxidation of cyanide. Although cyanate at high concentrations is toxic to E. coli, it can serve as a sole source of nitrogen due to the production of ammonia by cyanase [Sung87]. The cyanate degradation pathway therefore serves the dual purpose of detoxification and nitrogen utilization [Kozliak95].
Cyanase catalyzes the first step of the pathway, producing CO2 and the unstable compound carbamate. Carbamate spontaneously decomposes to CO2 and ammonia, thus producing a source of nitrogen for growth. The second enzyme of this pathway, carbonic anhydrase, is an essential component of the pathway. In the absence of carbonic anhydrase at atmospheric concentrations of CO2, non-enzymatic hydration of CO2 is not sufficient to prevent depletion of the intracellular bicarbonate pool due to rapid diffusion of CO2 [Guilloton93].
Guilloton93: Guilloton MB, Lamblin AF, Kozliak EI, Gerami-Nejad M, Tu C, Silverman D, Anderson PM, Fuchs JA (1993). "A physiological role for cyanate-induced carbonic anhydrase in Escherichia coli." J Bacteriol 1993;175(5);1443-51. PMID: 8444806
Anderson87: Anderson PM, Johnson WV, Endrizzi JA, Little RM, Korte JJ (1987). "Interaction of mono- and dianions with cyanase: evidence for apparent half-site binding." Biochemistry 26(13);3938-43. PMID: 3651424
Anderson88: Anderson PM, Johnson WV, Korte JJ, Xiong XF, Sung YC, Fuchs JA (1988). "Reversible dissociation of active octamer of cyanase to inactive dimer promoted by alteration of the sulfhydryl group." J Biol Chem 263(12);5674-80. PMID: 3128546
Anderson94: Anderson PM, Korte JJ, Holcomb TA, Cho YG, Son CM, Sung YC (1994). "Formation of intersubunit disulfide bonds and properties of the single histidine and cysteine residues in each subunit relative to the decameric structure of cyanase." J Biol Chem 269(21);15036-45. PMID: 8195141
Cronk01: Cronk JD, Endrizzi JA, Cronk MR, O'neill JW, Zhang KY (2001). "Crystal structure of E. coli beta-carbonic anhydrase, an enzyme with an unusual pH-dependent activity." Protein Sci 10(5);911-22. PMID: 11316870
DiazMejia09: Diaz-Mejia JJ, Babu M, Emili A (2009). "Computational and experimental approaches to chart the Escherichia coli cell-envelope-associated proteome and interactome." FEMS Microbiol Rev 33(1);66-97. PMID: 19054114
Hashimoto03: Hashimoto M, Kato J (2003). "Indispensability of the Escherichia coli carbonic anhydrases YadF and CynT in cell proliferation at a low CO2 partial pressure." Biosci Biotechnol Biochem 67(4);919-22. PMID: 12784642
Kozliak94: Kozliak EI, Guilloton MB, Gerami-Nejad M, Fuchs JA, Anderson PM (1994). "Expression of proteins encoded by the Escherichia coli cyn operon: carbon dioxide-enhanced degradation of carbonic anhydrase." J Bacteriol 176(18);5711-7. PMID: 8083164
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