Fig. 4 | npj Biofilms and Microbiomes

Fig. 4

From: New melanocortin-like peptide of E. coli can suppress inflammation via the mammalian melanocortin-1 receptor (MC1R): possible endocrine-like function for microbes of the gut

Fig. 4

a Structure of melanocortins and similar peptides. The four common melanocortins of mammals are derived from one pro-opiomelanocortin (POMC) precursor. ACTH and alpha-MSH are products of alternative processing of the same precursor and have very similar interactions with four of the melanocortin receptors. (The exception is MC2R; in the adrenal MC2R, is the dominant receptor and enables ACTH to have an effect that is orders of magnitude greater than that of alpha-MSH.) While the primary sequences of amino acids 1–13 are identical in ACTH and alpha-MSH, the latter has two post-translational moieties, an N-terminal acetyl and a C-terminal amide, that are important for full potency of alpha-MSH. That MECO-1 lacks the HFRW canonical sequence of the mammalian melanocortins but has bioactivity at MC1R equal to alpha-MSH was a surprise to us. Do note that three of the four substitutions are considered “conservative”. b Mitochondrial peptides. The C-termini of the two elongation factors of human mitochondria are compared to MECO-1. Note that each of them is about as close to MECO-1 as each is to the other. c Microbial peptides. The first eight sequences are those with the closest matches with MECO-1. The last two are from Bacteriodetes, organisms that are typically highly represented in the human colon

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