Identification and characterization of an abundant lipoprotein from Methylacidiphilum fumariolicum SolV

Abstract

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.

Identification and characterisation of a major outer membrane protein from Methylacidiphilum fumariolicum SolV

“…Our attention was drawn to the high expression of genes encoding two unknown proteins. One of them is WP_009060351 (gene: MFUM_0397 ), which ranks first among all lipoproteins and has been characterised recently (Liu et al 2023 ). This lipoprotein might play a vital role in the linkage between the OM and the peptidoglycan.…”

“…sp . Recently, we proposed a lipoprotein transport system (Liu et al 2023 ). Several genes lacking in the OMPs and lipoprotein transporter system may indicate strain SolV use a different and relatively simple system to perform this transport.…”

“…Upon analysis of the genome and transcriptomic data of M. fumariolicum SolV from different growth conditions, two highly expressed genes were attracting attention. One is the gene encoding a lipoprotein (protein ID: WP_009060351) characterised before (Liu et al 2023 ). The other gene MFUM_2087 is encoding an outer membrane protein WP_009059494, which ranks first among all outer membrane proteins and is characterised in this study.…”