Earthworm pre-procarboxypeptidase: a copper responsive enzyme.
This paper describes the identification and molecular cloning of the earthworm metalloenzyme preprocarboxypeptidase. It was possible to approximate the putative pre-pro cleavage sites, which after removal activates a 35.7 kDa mature peptide with a length of 317 amino acids. The primary, secondary and predicted tertiary structure of the mature chain is highly homologous to other carboxypeptidases from diverse phylogenetic origin. Using a fully quantitative PCR, we were able to assess relative expression of this gene in earthworms exposed to different heavy metal contaminated substrates. In summary, cadmium on its own or in combination with lead and zinc, did not trigger transcriptional up-regulation of carboxypeptidase. In contrast, copper exposed earthworms were assessed to have a 4-fold increase in carboxypeptidase transcript numbers. A hypothetical model is presented to explain how the exposure to heavy metals may influence transcriptional control and/or function of this enzyme. Finally, the significance of these observations in terms of risk assessment and biomonitoring of contaminated soils is discussed.
Stürzenbaum
S R
SR
School of Biosciences, University of Wales, Cardiff, UK. StiurzenbaumSR@Cardiff.ac.uk
Cater
S
S
Morgan
A J
AJ
Kille
P
P
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002268:Carboxypeptidases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D017124:Conserved Sequence; D003300:Copper / Q000633:toxicity*; D017931:DNA Primers / Q000235:genetics; D018076:DNA, Complementary / Q000235:genetics; D004785:Environmental Pollutants / Q000633:toxicity; D004792:Enzyme Precursors / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009835:Oligochaeta / Q000187:drug effects* / Q000201:enzymology* / Q000235:genetics; D010802:Phylogeny; D016133:Polymerase Chain Reaction; D017434:Protein Structure, Tertiary; D017386:Sequence Homology, Amino Acid
D017931:DNA Primers; D018076:DNA, Complementary; D004785:Environmental Pollutants; D004792:Enzyme Precursors; D003300:Copper; D002268:Carboxypeptidases