Identification and characterization of an abundant lipoprotein from Methylacidiphilum fumariolicum SolV

Bacterial lipoproteins are characterized by the presence of a conserved N-terminal lipid-modified cysteine residue that allows the hydrophilic protein to anchor into bacterial cell membranes. These lipoproteins play essential roles in a wide variety of physiological processes. Based on transcriptome analysis of the verrucomicrobial methanotroph Methylacidiphilum fumariolicum SolV, we identified a highly expressed lipoprotein, WP_009060351 (139 amino acids), in its genome. The first 86 amino acids are specific for the methanotrophic genera Methylacidiphilum and Methylacidmicrobium, while the last 53 amino acids are present only in lipoproteins of members from the phylum Verrucomicrobiota (Hedlund). Heterologous expression of WP_009060351 in Escherichia coli revealed a 25-kDa dimeric protein and a 60-kDa tetrameric protein. Immunoblotting showed that WP_009060351 was present in the total membrane protein and peptidoglycan fractions of M. fumariolicum SolV. The results suggest an involvement of lipoprotein WP_009060351 in the linkage between the outer membrane and the peptidoglycan.

Automated summary

Bacterial lipoproteins, characterized by a lipid-modified cysteine residue, have important roles in various physiological processes. The highly expressed lipoprotein WP_009060351 was identified in the genome of the methanotrophic bacterium Methylacidiphilum fumariolicum SolV through transcriptome analysis. Heterologous expression of WP_009060351 revealed its dimeric and tetrameric forms, and immunoblotting confirmed its presence in the membrane protein and peptidoglycan fractions. These results suggest the involvement of WP_009060351 in the linkage between the outer membrane and peptidoglycan.