Cloning, sequencing, and characterizing the Lactobacillus leichmannii pyrC gene encoding dihydroorotase

Area of Science:

• Microbiology
• Molecular Biology
• Biochemistry

Background:

• The pyrimidine biosynthetic pathway is crucial for cellular function.
• Dihydroorotase (DHOase) is a key enzyme in this pathway.
• Understanding bacterial enzyme genetics is important for various applications.

Purpose of the Study:

• To clone and characterize the gene encoding dihydroorotase (DHOase) from Lactobacillus leichmannii.
• To investigate the genetic regulation and protein characteristics of L. leichmannii DHOase.
• To compare the L. leichmannii DHOase with homologous enzymes from other species.

Main Methods:

• Cloning of the Lactobacillus leichmannii DHOase gene (pyrC) via phenotypic complementation of an E. coli pyrC deficient mutant.
• DNA sequencing and analysis of the open reading frame (ORF).
• Primer extension and Northern blot analysis for transcription initiation and gene expression studies.

Main Results:

• The L. leichmannii pyrC gene spans 1281 bp, encoding a 427 amino acid polypeptide (46,316 Da).
• Transcription initiation site identified 37 bp upstream of the start codon.
• Independent transcription of the pyrC gene confirmed, separate from the adjacent pyrB gene.
• 46.6% amino acid sequence identity observed between L. leichmannii DHOase and the Bacillus subtilis enzyme.

Conclusions:

• The L. leichmannii DHOase gene has been successfully cloned and characterized.
• Conserved protein domains suggest functional importance for the enzyme.
• This study contributes to the understanding of pyrimidine biosynthesis in bacteria.