Discovery of Novel Tyrosine Ammonia Lyases for the Enzymatic Synthesis of <i>p</i>‐Coumaric Acid
Yannik Brack, Chenghai Sun, Dong Yi, Uwe T. Bornscheuer
Abstract
Abstract p ‐Coumaric acid ( p ‐CA) is a key precursor for the biosynthesis of flavonoids. Tyrosine ammonia lyases (TALs) specifically catalyze the synthesis of p ‐CA from l ‐tyrosine, which is a convenient enzymatic pathway. To explore novel and highly active TALs, a phylogenetic tree‐building approach was conducted including 875 putative TALs and 46 putative phenylalanine/tyrosine ammonia lyases (PTALs). Among them, 5 TALs and 3 PTALs were successfully characterized and found to exhibit the proposed enzymatic activity. The TAL from Chryseobacterium luteum sp. nov (TAL clu ) has the highest affinity ( K m =0.019 m m ) and conversion efficiency ( k cat / K m= 1631 s −1 ⋅ m m −1 ) towards l ‐tyrosine. The reaction conditions for two purified enzymes and their E. coli recombinant cells were optimized and p ‐CA yields of 2.03 g/L after 8 hours by TAL clu and 2.35 g/L after 24 h by TAL from Rivularia sp. PCC 7116 (TAL rpc ) in whole cells were achieved. These TALs are thus candidates for the construction of whole‐cell systems to produce the flavonoid precursor p ‐CA.