Archives of Microbiology

, Volume 160, Issue 2, pp 126–131

The malonate decarboxylase enzyme system of Malonomonas rubra: evidence for the cytoplasmic location of the biotin-containing component


  • Hubert Hilbi
    • Mikrobiologisches Institut, Eidgenössische Technische HochschuleETH-Zentrum
  • René Hermann
    • Mikrobiologisches Institut, Eidgenössische Technische HochschuleETH-Zentrum
  • Peter Dimroth
    • Mikrobiologisches Institut, Eidgenössische Technische HochschuleETH-Zentrum
Original Papers

DOI: 10.1007/BF00288714

Cite this article as:
Hilbi, H., Hermann, R. & Dimroth, P. Arch. Microbiol. (1993) 160: 126. doi:10.1007/BF00288714


Malonate decarboxylase of Malonomonas rubra is a complex enzyme system involving cytoplasmic and membrane-bound components. One of these is a biotin-containing protein of Mr 120'000, the location of which in the cytoplasm was deduced from the following criteria: (i) If the cytoplasm was incubated with avidin and the malonate decarboxylase subsequently completed with the membrane fraction the decarboxylase activity was abolished. The corresponding incubation of the membrane with avidin, however, was without effect. (ii) Western blot analysis identified the single biotin-containing polypeptide of Mr 120'000 within the cytoplasm. (iii) Transmission electron micrographs of immuno-gold labeled M. rubra cells clearly showed the location of the biotinyl protein within the cytoplasm, whereas the same procedure with Propionigenium modestum cells indicated the location of the biotin enzyme methylmalonyl-CoA decarboxylase in the cell membrane. The biotin-containing protein of the M. rubra malonate decarboxylase enzyme system was not retained by monomeric avidin-Sepharose columns but could be isolated with this column in a catalytically inactive form in the presence of detergents. If the high binding affinity of tetrameric avidin towards biotin was reduced by destructing part of the tryptophan residues by irradiation or oxidation with periodate, the inhibition of malonate decarboxylase by the modified avidin was partially reversed with an excess of biotin. Attempts to purify the biotin protein in its catalytically active state using modified avidin columns were without success.

Key words

Malonomonas rubraPropionigenium modestumMalonate decarboxylaseMethylmalonyl-CoA decarboxylaseBiotinAvidinElectron microscopyHigh pressure freezingImmunolabeling

Copyright information

© Springer Verlag 1993