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 mm) and conversion efficiency (k(cat) /K(m=) 1631 s(-1) ⋅ mm(-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.