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Rational engineering of the TOL meta ‐cleavage pathway
Author(s) -
Sheridan Rose,
Jackson Graham A.,
Ward John,
Dunnill Peter
Publication year - 1998
Publication title -
biotechnology and bioengineering
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.136
H-Index - 189
eISSN - 1097-0290
pISSN - 0006-3592
DOI - 10.1002/(sici)1097-0290(19980420)58:2/3<240::aid-bit17>3.0.co;2-g
Subject(s) - pseudomonas putida , catechol , chemistry , metabolic pathway , dioxygenase , cleavage (geology) , enzyme , stereochemistry , metabolic intermediate , flux (metallurgy) , biochemistry , biology , organic chemistry , paleontology , fracture (geology)
The meta ‐cleavage pathway of Pseudomonas putida mt‐2 was simulated using a biochemical systems simulation developed by Regan (1996). A non‐competitive inhibition term for catechol‐2,3‐dioxygenase (C23O) by 2‐OH‐pent‐2,4‐dienoate (K i = 150 μ M ) was incorporated into the model. The simulation predicted steady state accumulation levels in the μ M range for metabolites pre‐ meta ‐cleavage, and in the m M range for metabolites post‐ meta ‐cleavage. The logarithmic gains L[ V − i , X j ] and L[ X − i , X j ] clearly indicated that the pathway was most sensitive to the concentration of the starting substrate, benzoate, and the first enzyme of the pathway, toluate‐1,2‐dioxygenase (TO). The simulation was validated experimentally; it was found that the amplification of TO increased the steady state flux from 0.024 to 0.091 (mmol/g cell dwt)/h. This resulted in an increased accumulation of a number of the pathway metabolites (intra‐ and extracellularly), especially cis ‐diol, 4‐OH‐2‐oxovalerate, and 4‐oxalocrotonate. Metabolic control analysis indicated that C23O was, in fact, the major controling enzymic step of the pathway with a scaled control coefficient of 0.83. The amplification of TO resulted in a shift of some of the control away from C23O. Catechol‐2,3‐dioxygenase, however, remained as the major controling element of the pathway. © 1998 John Wiley & Sons, Inc. Biotechnol Bioeng 58:240–249, 1998.