Biodegradation

, Volume 3, Issue 4, pp 423–434

Characterization of an inducible, membrane-bound iminodiacetate dehydrogenase from Chelatobacter heintzii ATCC 29600

Authors

  • Thomas Uetz
    • Federal Institute for Water Resources and Water Pollution Control (EAWAG)
    • Department of Microbiology, BiozentrumUniversity of Basel
    • Swiss Federal Institute of Technology
  • Thomas Egli
    • Federal Institute for Water Resources and Water Pollution Control (EAWAG)
    • Swiss Federal Institute of Technology
Article

DOI: 10.1007/BF00240364

Cite this article as:
Uetz, T. & Egli, T. Biodegradation (1992) 3: 423. doi:10.1007/BF00240364
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Abstract

Iminodiacetate (IDA) is a xenobiotic intermediate common to both aerobic and anaerobic metabolism of nitrilotriacetate (NTA). It is formed by either NTA monooxygenase or NTA dehydrogenase. In this paper the detection and characterization of a membrane-bound iminodiacete dehydrogenase (IDA-DH) from Chelatobacter heintzii ATCC 29600 is reported, which oxidizes IDA to glycine and glyoxylate. Out of 15 compounds tested, IDA was the only substrate for the enzyme. Optimum activity of IDA-DH was found at pH 8.5 and 25°C, respectively, and the Km for IDA was found to be 8mM. Activity of the membrane-bound enzyme was inhibited by KCN, antimycine and dibromomethylisopropyl-benzoquinone. When inhibited by KCN IDA-DH was able to reduce the artificial electron acceptor iodonitrotetrazolium (INT). It was possible to extract IDA-DH from the membranes with 2% cholate, to reconstitute the enzyme into soybean phospholipid vesicles and to obtain IDA-DH activity (more than 50% recovery) using ubiquinone Q1 as the intermediate electron carrier and INT as the final electron acceptor. Growth experiments with different substrates revealed that in all NTA-degrading strains tested both NTA monooxygenase and IDA-DH were only expressed when the cells were grown on NTA or IDA. Furthermore, in Cb. heintzii ATCC 29600 growing exponentially on succinate and ammonia, addition of 0.4 g l-1 NTA led to the induction of the two enzymes within an hour and NTA was utilized simultaneously with succinate. The presence of IDA-DH was confirmed in ten different NTA-degrading strains belonging to three different genera.

Key words

membrane proteinbiodegradationiminodiacetateiminodiacetate dehydrogenasenitrilotriacetate (NTA)ubiquinones

Abbreviations

cA

component A

cB

component B

DBMIB

dibromomethylisopropyl-benzoquinone

HEPES

hydroxyethylpiperazinethanesulfonic acid

IDA

iminodiacetate, HN(CH2COOH)2

IDA-DH

iminodiacetate dehydrogenase

INT

iodonitrotetrazolium chloride

NTA

nitrilotriacetate, N(CH2COOH)3

NTA-MO

nitrilotriacetate monooxygenase

PMS

phenazine methosulphate

SDS-PAGE

sodium dodecylsulfate polyacrylamide gel electrophoresis

Suc-DH

succinate dehydrogenase

Copyright information

© Kluwer Academic Publishers 1993