Format

Send to

Choose Destination
See comment in PubMed Commons below
J Bacteriol. 1994 Mar;176(6):1718-28.

3-Carboxy-cis,cis-muconate lactonizing enzyme from Neurospora crassa: an alternate cycloisomerase motif.

Author information

1
Department of Chemistry and Biochemistry, University of Maryland, College Park 20742.

Abstract

3-Carboxy-cis,cis-muconate lactonizing enzyme (CMLE; EC 5.5.1.5) from Neurospora crassa catalyzes the reversible gamma-lactonization of 3-carboxy-cis,cis-muconate by a syn-1,2 addition-elimination reaction. The stereochemical and regiochemical course of the reaction is (i) opposite that of CMLE from Pseudomonas putida (EC 5.5.1.2) and (ii) identical to that of cis,cis-muconate lactonizing enzyme (MLE; EC 5.5.1.1) from P. putida. In order to determine the mechanistic and evolutionary relationships between N. crassa CMLE and the procaryotic cycloisomerases, we have purified CMLE from N. crassa to homogeneity and determined its nucleotide sequence from a cDNA clone isolated from a p-hydroxybenzoate-induced N. crassa cDNA library. The deduced amino acid sequence predicts a protein of 41.2 kDa (365 residues) which does not exhibit sequence similarity with any of the bacterial cycloisomerases. The cDNA encoding N. crassa CMLE was expressed in Escherichia coli, and the purified recombinant protein exhibits physical and kinetic properties equivalent to those found for the isolated N. crassa enzyme. We also report that N. crassa CMLE possesses substantially reduced yet significant levels of MLE activity with cis,cis-muconate and, furthermore, does not appear to be dependent on divalent metals for activity. These data suggest that the N. crassa CMLE may represent a novel eucaryotic motif in the cycloisomerase enzyme family.

PMID:
8132467
PMCID:
PMC205260
[Indexed for MEDLINE]
Free PMC Article
PubMed Commons home

PubMed Commons

0 comments
How to join PubMed Commons

    Supplemental Content

    Full text links

    Icon for HighWire Icon for PubMed Central
    Loading ...
    Support Center