Coproheme decarboxylases - Phylogenetic prediction versus biochemical experiments

Area of Science:

• Biochemistry
• Molecular Biology
• Enzymology

Background:

• Coproheme decarboxylases (ChdCs) catalyze the final step in coproporphyrin-dependent heme biosynthesis.
• The gene encoding ChdCs is phylogenetically widespread across bacteria and Archaea.

Purpose of the Study:

• To investigate the phylogenetic distribution and functional activity of ChdCs.
• To test the reliability of phylogenetic predictions for enzymatic function.
• To identify conserved sequence motifs associated with ChdC activity.

Main Methods:

• Phylogenetic analysis of ChdC genes across diverse microbial clades.
• Heterologous expression of ChdC representatives.
• Biochemical assays to determine coproheme decarboxylase activity.
• Sequence motif identification.

Main Results:

• ChdC genes are present in monoderm bacteria, diderm bacteria, and Archaea.
• Active coproheme decarboxylase activity was confirmed in diderm bacteria for the first time.
• The archaeal ChdC homolog from Sulfolobus solfataricus was found to be inactive.
• A conserved sequence motif (-Y-P-M/F-X-K/R-) was identified for ChdCs.
• Phylogenetic conservation of the motif did not always correlate with enzymatic activity.

Conclusions:

• Diderm bacteria possess functional coproheme decarboxylases.
• Phylogenetic analysis alone is insufficient to predict enzymatic activity, as demonstrated by the inactive archaeal ChdC.
• The identified sequence motif is a useful, but not definitive, marker for ChdC function.