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Protein of unknown function (DUF3108) This is a bacterial family of putative lipoproteins. The structure for Swiss:Q64U78, PDB:3fzx, the first structural template for this large family including several homologs in the human gut microbiome and in metagenomic datasets, folds into a beta barrel that topologically looks like a small-scale porin (such as FepA). Swiss:Q64U78 is a putative exported protein, and this fold is of the YmcC-like type, with a predicted signal peptide SpI cleavage site AGAMA|QNQDC, and a Phobius server prediction of non-cytoplasmic localization for amino acids 21-236. The possibility of it being a membrane protein can be ruled out by the hydrophilic nature of the solvent exposed surface outside the barrels. Analysis of sequence conservation suggests that an area near Glu172/Trp206 is potentially interesting. These two residues are also conserved in Dali hit PDB:2in5, a hypothetical lipoprotein classified as a new YmcC-like fold in SCOP (SCOP:159271, with a 12-stranded meander beta-sheet folded into a deformed beta-barrel) despite large structural differences between the two structures, suggesting similarity in function. |
Jiyao W et al.(2023). "The conserved domain database in 2023.",