Conservation of primary structure in prokaryotic hydrogenases

Area of Science:

• Biochemistry
• Molecular Biology
• Microbial Genetics

Background:

• Prokaryotic (NiFe)-hydrogenases exhibit conserved primary sequences, suggesting a common evolutionary origin.
• Specific cysteine and histidine residues are critical for enzyme activity, ligand, and cofactor binding in these enzymes.

Purpose of the Study:

• To investigate the evolutionary origins and conserved functional regions of prokaryotic (NiFe)-hydrogenases.
• To identify regulatory sequences controlling the expression of methyl-viologen hydrogenase genes in Methanobacterium thermoautotrophicum.

Main Methods:

• Primary sequence analysis of (NiFe)-hydrogenases.
• Comparative sequence analysis of intergenic regions in Methanobacterium thermoautotrophicum strains.

Main Results:

• Evidence suggests a common ancestral sequence for all studied prokaryotic (NiFe)-hydrogenases.
• Highly conserved cysteinyl and histidinyl residues are identified as essential for enzyme function.
• A conserved sequence of over 100 base pairs upstream of methyl-viologen hydrogenase genes was found in multiple M. thermoautotrophicum strains.

Conclusions:

• Prokaryotic (NiFe)-hydrogenases evolved from a single ancestral gene.
• Conserved residues play vital roles in the catalytic activity and cofactor binding of hydrogenases.
• The identified conserved intergenic sequence is essential for regulating hydrogenase gene expression in M. thermoautotrophicum.