Sequence and expression of a halobacterial beta-galactosidase gene

Area of Science:

• Microbiology
• Molecular Biology
• Biochemistry

Background:

• Gene expression studies in haloarchaea are limited by the absence of a suitable reporter gene.
• Previous work identified and sequenced peptides from a beta-galactosidase in Haloferax alicantei.

Purpose of the Study:

• To clone and characterize the beta-galactosidase gene (bgaH) from Haloferax alicantei.
• To develop a functional reporter gene for gene expression analysis in haloarchaea.

Main Methods:

• Peptide sequences were used to clone the bgaH gene and flanking DNA.
• Bioinformatic analysis of the deduced amino acid sequence.
• Engineering the bgaH gene into a halobacterial plasmid vector for transformation.
• Assessing enzyme activity in transformants using Xgal and ONPG assays.

Main Results:

• The complete bgaH gene was cloned and sequenced.
• The deduced BgaH protein (74 kDa) showed similarity to glycosyl hydrolase family 42.
• Upstream ORFs indicated involvement in carbohydrate metabolism; a downstream ORF contained a fibronectin III motif.
• Functional expression of BgaH in Haloferax volcanii was confirmed by blue colony formation on Xgal and quantifiable ONPG assay results.

Conclusions:

• The cloned bgaH gene provides a novel and functional beta-galactosidase reporter system for haloarchaea.
• This reporter system facilitates gene expression studies in previously challenging organisms.
• The bgaH gene is a valuable tool for molecular biology research in halophilic archaea.