The sequence of the Haemophilus influenzae mutB gene indicates it encodes a DNA helicase II-like protein

Area of Science:

• Microbiology
• Molecular Biology
• Genetics

Background:

• The mutator and UV sensitive phenotypes of Haemophilus influenzae mutB1 mutants indicate defects in DNA repair pathways.
• Understanding the genetic basis of DNA repair is crucial for microbial genetics and understanding mutagenesis.

Purpose of the Study:

• To isolate and characterize the gene responsible for complementing the mutator and UV sensitive phenotypes in H. influenzae.
• To elucidate the molecular function of the H. influenzae mutB gene.

Main Methods:

• Genomic DNA fragment isolation and complementation assays in H. influenzae and Escherichia coli.
• Nucleotide sequencing of the isolated DNA fragment.
• Bioinformatic analysis to identify open reading frames (ORFs) and compare sequences with known genes.

Main Results:

• A 6.2-kb DNA fragment from H. influenzae was isolated that complemented mutator and UV sensitive phenotypes.
• The fragment contained a 2184 bp ORF with significant nucleotide and amino acid similarity to the E. coli uvrD gene.
• Sequence analysis revealed conserved helicase superfamily domains and potential regulatory motifs, including a LexA-binding site.

Conclusions:

• The H. influenzae mutB gene encodes an ATP-dependent DNA helicase-like activity.
• This enzyme likely plays a role in DNA repair and/or mutagenesis in H. influenzae.
• The findings provide insights into the conservation of DNA repair mechanisms across bacterial species.