A Tyrosine Aminomutase from Rice (Oryza sativa) Isomerizes (S)-α- to (R)-β-Tyrosine with Unique High Enantioselectivity and Retention of Configuration

Abstract

A recently discovered 3,5-dihydro-5-methylidene-4H-imidazol-4-one (MIO)-dependent tyrosine aminomutase (OsTAM) from rice [Yan, J., et al. (2015) Plant Cell 27, 1265] converts (S)-α-tyrosine to a mixture of (R)- and (S)-β-tyrosines, with high (94%) enantiomeric excess, which does not change with pH, like it does for two bacterial TAMs. The K(M) of 490 μM and the k(cat) of 0.005 s(-1) are similar for other TAM enzymes. OsTAM is unique and also catalyzes (R)-β- from (S)-α-phenylalanine. OsTAM principally retains the configuration at the reactive C(α) and C(β) centers during catalysis much like the phenylalanine aminomutase on the Taxol biosynthetic pathway in Taxus plants.

Enantiomer discrimination in β-phenylalanine degradation by a newly isolated Paraburkholderia strain BS115 and type strain PsJN

“…The reported reaction time for chiral resolution was quite long with more than 48 h using 2 mM of substrate (Wu et al 2010 ). Apart from this also β-tyrosine aminomutase is known from Oryzae sativa with high enantioselectivity towards ( R )-β-PA (Walter et al 2016 ). So a slow enzymatic racemization of ( R )-PA to ( S )-PA and further metabolization of the latter by BS115 appears at least possible; but no bacterial aminomutase with such an activity is known until now.…”

Efficient production of phenylpropionic acids by an amino‐group‐transformation biocatalytic cascade

“…Another example is (R)-β-tyrosine, which is usually produced by the amino shift of (S)-α-tyrosine using tyrosine AMs (Christenson, Liu, Toney, & Shen, 2003;Rachid, Krug, Weissman, & Muller, 2007;Walter et al, 2016). Compared with that of tyrosine AMs, the TcPAM C107S, L104A obtained by protein engineering here showed high enzyme activity and enantioselectivity.…”

“…So far, three AMs are known to isomerize ( S )‐α‐tyrosine to ( R )‐β‐tyrosine. The enzymes from Chondromyces crocatus ( Cc TAM; Krug & Muller, ) and Oryze sativa ( Os TAM; Walter, King, & Walker, ) catalyze a mixture of ( R )‐ and ( S )‐β‐tyrosine, with 69% and 94% e.e. for the ( R )‐isomer, respectively.…”

“…By cofactor recycling and enzyme expression optimization, this cascade achieved excellent conversion (98%); it was more efficient than the kinetic resolution method (Sealock, ). Another example is ( R )‐β‐tyrosine, which is usually produced by the amino shift of ( S )‐α‐tyrosine using tyrosine AMs (Christenson, Liu, Toney, & Shen, ; Rachid, Krug, Weissman, & Muller, ; Walter et al, ). Compared with that of tyrosine AMs, the Tc PAM C107S, L104A obtained by protein engineering here showed high enzyme activity and enantioselectivity.…”

“…The enzymes from Chondromyces crocatus (CcTAM; Krug & Muller, 2009) and Oryze sativa (OsTAM; Walter, King, & Walker, 2016) catalyze a mixture of (R)-and (S)-β-tyrosine, with 69% and 94% e.e. for the (R)-isomer, respectively.…”