Assigning a function to a conserved archaeal metallo-β-lactamase from Haloferax volcanii

Area of Science:

• Biochemistry
• Molecular Biology
• Archaea Biology

Background:

• Metallo-β-lactamases are enzymes with diverse cellular roles, including DNA and RNA metabolism.
• Many prokaryotic metallo-β-lactamases are uncharacterized, lacking proven functions.
• HVO_2763 from Haloferax volcanii is a potential metallo-β-lactamase with sequence similarity to tRNA 3' processing endonuclease tRNase Z.

Purpose of the Study:

• To characterize the function of the metallo-β-lactamase HVO_2763 in the halophilic archaeon Haloferax volcanii.
• To determine if HVO_2763 possesses tRNA 3' processing or exonuclease activity.
• To investigate potential roles of HVO_2763 in cellular processes based on its deletion mutant phenotype.

Main Methods:

• Recombinant expression and in vitro activity assays of HVO_2763.
• Transcriptome analysis of a HVO_2763 deletion strain in Haloferax volcanii.
• Biochemical characterization of enzyme activity.

Main Results:

• In vitro assays demonstrated that recombinant HVO_2763 lacks tRNA 3' processing and exonuclease activity.
• Transcriptome analysis revealed downregulation of membrane transport-related proteins in the HVO_2763 deletion mutant.
• The characterized function of HVO_2763 differs from its sequence homolog, tRNase Z.

Conclusions:

• HVO_2763 is not a functional tRNA 3' processing endonuclease or exonuclease.
• HVO_2763 from Haloferax volcanii is likely involved in membrane transport, either directly or indirectly.
• This study highlights the importance of functional characterization beyond sequence homology for unannotated proteins.