Metabolic coupling of two small-molecule thiols programs the biosynthesis of lincomycin A

Abstract

Low-molecular-mass thiols in organisms are well known for their redox-relevant role in protection against various endogenous and exogenous stresses. In eukaryotes and Gram-negative bacteria, the primary thiol is glutathione (GSH), a cysteinyl-containing tripeptide. In contrast, mycothiol (MSH), a cysteinyl pseudo-disaccharide, is dominant in Gram-positive actinobacteria, including antibiotic-producing actinomycetes and pathogenic mycobacteria. MSH is equivalent to GSH, either as a cofactor or as a substrate, in numerous biochemical processes, most of which have not been characterized, largely due to the dearth of information concerning MSH-dependent proteins. Actinomycetes are able to produce another thiol, ergothioneine (EGT), a histidine betaine derivative that is widely assimilated by plants and animals for variable physiological activities. The involvement of EGT in enzymatic reactions, however, lacks any precedent. Here we report that the unprecedented coupling of two bacterial thiols, MSH and EGT, has a constructive role in the biosynthesis of lincomycin A, a sulfur-containing lincosamide (C8 sugar) antibiotic that has been widely used for half a century to treat Gram-positive bacterial infections. EGT acts as a carrier to template the molecular assembly, and MSH is the sulfur donor for lincomycin maturation after thiol exchange. These thiols function through two unusual S-glycosylations that program lincosamide transfer, activation and modification, providing the first paradigm for EGT-associated biochemical processes and for the poorly understood MSH-dependent biotransformations, a newly described model that is potentially common in the incorporation of sulfur, an element essential for life and ubiquitous in living systems.

C-S bond cleavage by a polyketide synthase domain

“…1 and 3) with similar k cat /K m values ( Table 1). The observed K m values of LnmJ-SH, CaJ-SH, and MaJ-SH with all tested substrates (1)(2)(3)(4)(5)(6)(7)(8)(9)(10) are between 1.9 ± 0.2 and 42 ± 6 mM (Table 1), which are too high to be relevant under the physiological reactions. These high K m values may result from the structural difference between the native substrates of the SH domains and the substrate mimics tested, the fact that the SH domains were studied in isolation (i.e., in truncation lacking the context of other domains within the native PKS modules), or a combination of both (Fig.…”

“…Sulfur-containing metabolites are well known from both primary and secondary metabolism (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15). The best-characterized sulfur-incorporating enzymes from primary metabolism include the following: (i) the group I and II cysteine desulfurases that use L-cysteine as the substrate and catalyze the production of a protein-bound persulfide and alanine, as exemplified by NifS, IscC, and CsdB (1-3); (ii) the D-cysteine desulfhydrases that use D-cysteine as the substrate and catalyze the β-elimination reaction to produce hydrogen sulfide, ammonia, and pyruvate (32); and (iii) the cysteine S-conjugate β-lyases that use L-cysteine-S-conjugates as the substrates and catalyze the β-elimination reaction to produce a thiol, ammonia, and pyruvate (33).…”

“…However, sulfur incorporation into other natural products remains poorly understood. Only a few cases featured by C-S bond formation or C-S bond cleavage steps were reported to date, and most of the mechanisms require further investigation (6)(7)(8)(9)(10)(11)(12)(13)(14)(15).…”

Regulation of Ergothioneine Biosynthesis and Its Effect on Mycobacterium tuberculosis Growth and Infectivity

“…For example, EGT was recently observed to be involved in C8 sugar transfer and activation in the biosynthesis of the antibiotic lincomycin A in Streptomyces lincolnensis (50). In this reaction, EGT served as a carrier during the first glycosylation step to channel the lincosamine unit for further condensation with a methylated derivative of 4-propyl-L-proline.…”

Biotransformation of acetophenone to 1-phenylethanol by fungi

“…Cultured microorganisms are therefore frequently used to catalyze reactions such as hydrolysis [1][2][3][4], addition [5], substitution [6][7][8][9], oxidation [10][11][12][13], reduction [14][15][16], prenylation [17][18][19][20][21], and glycosylation [22][23][24][25]. Biotransformations are particularly advantageous compared to organic chemical syntheses because optically active molecules are produced from prochiral substrates, and chiral alcohols are important products of the pharmaceutical industry [26][27][28][29].…”