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Evidence that particulate methane monooxygenase and ammonia monooxygenase may be evolutionarily related
A J Holmes1, A Costello, M E Lidstrom
1Department of Biological Science, University of Warwick, Coventry, UK.
Abstract:
Genes encoding particulate methane monooxygenase and ammonia monooxygenase share high sequence identity. Degenerate oligonucleotide primers were designed, based on regions of shared amino acid sequence between the 27-kDa polypeptides, which are believed to contain the active sites, of particulate methane monooxygenase and ammonia monooxygenase. A 525-bp internal DNA fragment of the genes encoding these polypeptides (pmoA and amoA) from a variety of methanotrophic and nitrifying bacteria was amplified by PCR, cloned and sequenced. Representatives of each of the phylogenetic groups of both methanotrophs (alpha- and gamma-Proteobacteria) and ammonia-oxidizing nitrifying bacteria (beta- and gamma-Proteobacteria) were included. Analysis of the predicted amino acid sequences of these genes revealed strong conservation of both primary and secondary structure. Nitrosococcus oceanus AmoA showed higher identity to PmoA sequences from other members of the gamma-Proteobacteria than to AmoA sequences. These results suggest that the particulate methane monooxygenase and ammonia monooxygenase are evolutionarily related enzymes despite their different physiological roles in these bacteria.
Insights
Particulate methane monooxygenase and ammonia monooxygenase enzymes, crucial for methane oxidation and ammonia oxidation respectively, show significant evolutionary relatedness. Their genes (pmoA and amoA) share high sequence identity, suggesting a common ancestry despite distinct functions.
Area of Science:
- Microbiology
- Molecular Biology
- Biochemistry
Background:
- Particulate methane monooxygenase (pMMO) and ammonia monooxygenase (AMO) are key enzymes in methane and ammonia oxidation, respectively.
- These enzymes are found in methanotrophic and nitrifying bacteria, respectively, playing critical roles in biogeochemical cycles.
- High sequence identity between pmoA and amoA genes suggests potential evolutionary links.
Purpose of the Study:
- To investigate the evolutionary relationship between particulate methane monooxygenase and ammonia monooxygenase.
- To analyze the sequence conservation of pmoA and amoA genes across different bacterial groups.
- To explore the implications of sequence similarity for enzyme function and evolution.
Main Methods:
- Design of degenerate oligonucleotide primers based on conserved amino acid sequences of pMMO and AMO active sites.
- Polymerase chain reaction (PCR) amplification of a 525-bp DNA fragment from pmoA and amoA genes.
- Cloning and sequencing of amplified gene fragments from diverse methanotrophic (alpha- and gamma-Proteobacteria) and ammonia-oxidizing bacteria (beta- and gamma-Proteobacteria).
Main Results:
- Successful amplification and sequencing of pmoA and amoA gene fragments from various bacterial groups.
- Analysis revealed strong conservation in primary and secondary structures of the predicted amino acid sequences.
- Nitrosococcus oceanus AmoA exhibited higher sequence identity to gamma-Proteobacteria PmoA than to other AmoA sequences.
Conclusions:
- The particulate methane monooxygenase and ammonia monooxygenase enzymes are evolutionarily related.
- Sequence conservation supports a shared ancestry despite differing physiological roles.
- The findings provide insights into the evolution of microbial enzymes involved in key biogeochemical processes.