Lugdunin

Lugdunin

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Names
IUPAC name (1R,4R,7S,10R,13S,16R,19S)-7-(1H-Indol-3-ylmethyl)-10-isobutyl-4,13,16,19-tetraisopropyl-21-thia-3,6,9,12,15,18,23-heptaazabicyclo[18.2.1]tricosane-2,5,8,11,14,17-hexone
Identifiers
CAS Number	1989698-37-4
3D model (JSmol)	Interactive image
ChEBI	CHEBI:133127 checkY
ChemSpider	57427231
ECHA InfoCard
E number
PubChem CID	121596231
CompTox Dashboard (EPA)	{{#property:P3117}}
InChI InChI=1S/C40H62N8O6S/c1-19(2)15-27-35(50)45-31(21(5)6)38(53)47-32(22(7)8)39(54)48-33(23(9)10)40-44-29(18-55-40)36(51)46-30(20(3)4)37(52)43-28(34(49)42-27)16-24-17-41-26-14-12-11-13-25(24)26/h11-14,17,19-23,27-33,40-41,44H,15-16,18H2,1-10H3,(H,42,49)(H,43,52)(H,45,50)(H,46,51)(H,47,53)(H,48,54)/t27-,28+,29+,30-,31+,32-,33+,40?/m1/s1 Key: QZNGYMKAHFFKCJ-ZBQZSICZSA-N InChI=1/C40H62N8O6S/c1-19(2)15-27-35(50)45-31(21(5)6)38(53)47-32(22(7)8)39(54)48-33(23(9)10)40-44-29(18-55-40)36(51)46-30(20(3)4)37(52)43-28(34(49)42-27)16-24-17-41-26-14-12-11-13-25(24)26/h11-14,17,19-23,27-33,40-41,44H,15-16,18H2,1-10H3,(H,42,49)(H,43,52)(H,45,50)(H,46,51)(H,47,53)(H,48,54)/t27-,28+,29+,30-,31+,32-,33+,40?/m1/s1 Key: QZNGYMKAHFFKCJ-ZBQZSICZBY
SMILES CC(C)C[C@@H]1C(=O)N[C@H](C(=O)N[C@@H](C(=O)N[C@H](C2N[C@@H](CS2)C(=O)N[C@@H](C(=O)N[C@H](C(=O)N1)Cc3c[nH]c4c3cccc4)C(C)C)C(C)C)C(C)C)C(C)C
Properties
Chemical formula	C40H62N8O6S
Molar mass	783.05 g·mol−1
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Infobox references

Lugdunin is an investigational antibiotic, classified as a thiazolidine-containing cyclic peptide. It was isolated in 2016 after Staphylococcus lugdunensis was identified as the species of bacteria from the human nose that suppressed growth of species of disease-causing bacteria in that part of the human microbiome.

Lugdunin is a non-ribosomally synthesized cyclic peptide that inhibits growth of Staphylococcus aureus strains. The lugdunin genes are located on a 30-kbp operon. The genes lugA, lugB, lugC, and lugD encode four non-ribosomal peptide synthases, which are preceded by a putative regulator gene lugR.

Gene	locustag	protein size/aa	Genbank protein entry	RefSeq protein entry
lugR	SLUG_RS03935	196	CCB53263.1	WP_002460032.1
lugA	SLUG_RS03940	2374	CCB53264.1	WP_002478842.1
	SLUG_RS03945	124	CCB53265.1	WP_002460029.1
lugB	SLUG_RS03950	1230	CCB53266.1	WP_014533237.1
lugC	SLUG_RS03955	2937	CCB53267.1	WP_002478844.1
lugT	SLUG_RS03960	228	CCB53268.1	WP_002460022.1
lugD	SLUG_RS03965	579	CCB53269.1	WP_002478846.1

ChemDraw image depicting the synthesis of lugdunin. The synthesis proceeds in typical NRPS fashion with four distinct domains.

The NRPS synthesis of lugdunin prior to cyclization and thiazolidine formation.

Biosynthesis

Lugdunin is synthesized by non ribosomal peptide synthetases in S. lugdunensis. The molecule is a cyclic peptide composed of a thiazolidine heterocycle and three D amino acids. The operon responsible for lugdunin synthesis is approximately 30 kb and contains four non ribosomal peptide synthetase genes. The operon contains a phosphopantetheinyl transferase, monooxygenase, an unknown tailoring enzyme, a regulator gene, and a type II thioesterase. Phosphopantetheinyl transferases carry out the activation of T domains, which act as carrier proteins. Monooxygenases incorporate a single hydroxyl into a lugdunin intermediate. The type II thioesterase is utilized to remove intermediates that stall during biosynthesis.

A surprising note about lugdunin is that the operon only encodes five adenylation domains, an interestingly small amount for such a large molecule. This discrepancy is accounted for by the addition of three consecutive valine residues in alternating D and L configurations by LugC. The thiazolidine ring forms following the release of the metabolite via reduction. The N-terminal L-Cysteine residue nucleophilically attacks the carbonyl on the C-terminal L-valine residue, thus forming an imine macrocycle. The Schiff base formed in this reaction is then nucleophilically attacked by a cysteine thiol which produces the thiazolidine heterocycle previously described.