Kegg Pathway: Biosynthesis of 12-, 14- and 16-membered macrolides

Appl Microbiol Biotechnol. 2007 Oct; 76(6): 1373-81
Jung WS, Han AR, Hong JS, Park SR, Choi CY, Park JW, Yoon YJ

To develop a system for combinatorial Biosynthesis of glycosylated macrolides, Streptomyces venezuelae was genetically manipulated to be deficient in the production of its macrolide antibiotics by deletion of the entire biosynthetic gene cluster encoding the pikromycin polyketide synthases and desosamine biosynthetic enzymes. Two engineered deoxysugar biosynthetic pathways for the Biosynthesis of thymidine diphosphate (TDP)-D-quinovose or TDP-D-olivose in conjunction with the glycosyltransferase-auxiliary protein pair DesVII/DesVIII derived from S. venezuelae were expressed in the mutant strain. Feeding the representative 12-, 14-, and 16-membered ring macrolactones including 10-deoxymethynolide, narbonolide, and tylactone, respectively, to each mutant strain capable of producing TDP-D-quinovose or TDP-D-olivose resulted in the successful production of the corresponding quinovose- and olivose-glycosylated macrolides. In mutant strains where the DesVII/DesVIII glycosyltransferase-auxiliary protein pair was replaced by TylMII/TylMIII derived from Streptomyces fradiae, quinovosyl and olivosyl tylactone were produced; however, neither glycosylated 10-deoxymethynolide nor narbonolide were generated, suggesting that the glycosyltransferase TylMII has more stringent substrate specificity toward its aglycones than DesVII. These results demonstrate successful generation of structurally diverse hybrid macrolides using a S. venezuelae in vivo system and provide further insight into the substrate flexibility of glycosyltransferases.

Chem Biol. 2006 Nov; 13(11): 1203-15
Proisy N, Sharp SY, Boxall K, Connelly S, Roe SM, Prodromou C, Slawin AM, Pearl LH, Workman P, Moody CJ

A series of benzo-macrolactones of varying ring size and conformation has been prepared by chemical synthesis and evaluated by structural and biological techniques. Thus, 12- to 16-membered lactones were obtained by concise routes, involving ring-closing metathesis as a key step. In enzyme assays, the 13-, 15-, and 16-membered analogs are good inhibitors, suggesting that they can adopt the required conformation to fit in the ATP-binding site. This was confirmed by cocrystallization of 13-, 14-, and 15-membered lactones with the N-terminal domain of yeast Hsp90, showing that they bind similarly to the "natural" 14-membered radicicol. The most active compounds in the ATPase assays also showed the greatest growth-inhibitory potency in HCT116 human colon cancer cells and the established molecular signature of Hsp90 inhibition, i.e., depletion of client proteins with upregulation of Hsp70.

J Antimicrob Chemother. 2004 Feb; 53(2): 367-70
Ortega E, Escobar MA, Gaforio JJ, Algarra I, Alvarez De Cienfuegos G

OBJECTIVES: The aim of this study was to determine whether pre-incubation of peritoneal or splenic cells with different doses of the macrolides erythromycin A (14-membered ring), azithromycin (15-membered ring) and josamycin (16-membered ring) affects their phagocytic activity or cytokine production. METHODS: Peritoneal and splenic cells from BALB/c mice were pre-incubated with different concentrations of these antibiotics, those similar to serum levels attained with the treatment schedules used in human therapy. RESULTS: From our observations of phagocytic activity and IL-12 production by peritoneal cells, these macrolide antibiotics seem to act mainly as immunosuppressive agents, although they induce peritoneal cells to increase IL-18 production and splenic cells IL-4 production. CONCLUSIONS: Macrolide antibiotics can interfere with the Th1 cell-amplifying activity of IL-18 in conjunction with IL-12 and, in contrast, may induce a Th2 cell response in an IL-4-dependent manner. These results could improve their therapeutic use especially in immunosuppressed patients.

Drugs. 2001; 61(4): 443-98
Zhanel GG, Dueck M, Hoban DJ, Vercaigne LM, Embil JM, Gin AS, Karlowsky JA

The first macrolide, erythromycin A, demonstrated broad-spectrum antimicrobial activity and was used primarily for respiratory and skin and soft tissue infections. Newer 14-, 15- and 16-membered ring macrolides such as clarithromycin and the azalide, azithromycin, have been developed to address the limitations of erythromycin. The main structural component of the macrolides is a large lactone ring that varies in size from 12 to 16 atoms. A new group of 14-membered macrolides known as the ketolides have recently been developed which have a 3-keto in place of the L-cladinose moiety. macrolides reversibly bind to the 23S rRNA and thus, inhibit protein synthesis by blocking elongation. The ketolides have also been reported to bind to 23S rRNA and their mechanism of action is similar to that of macrolides. Macrolide resistance mechanisms include target site alteration, alteration in antibiotic transport and modification of the antibiotic. The macrolides and ketolides exhibit good activity against gram-positive aerobes and some gram-negative aerobes. Ketolides have excellent activity versus macrolide-resistant Streptococcus spp. Including mefA and ermB producing Streptococcus pneumoniae. The newer macrolides, such as azithromycin and clarithromycin, and the ketolides exhibit greater activity against Haemophilus influenzae than erythromycin. The bioavailability of macrolides ranges from 25 to 85%, with corresponding serum concentrations ranging from 0.4 to 12 mg/L and area under the concentration-time curves from 3 to 115 mg/L x h. Half-lives range from short for erythromycin to medium for clarithromycin, roxithromycin and ketolides, to very long for dirithromycin and azithromycin. All of these agents display large volumes of distribution with excellent uptake into respiratory tissues and fluids relative to serum. The majority of the agents are hepatically metabolised and excretion in the urine is limited, with the exception of clarithromycin. Clinical trials involving the macrolides are available for various respiratory infections. In general, macrolides are the preferred treatment for community-acquired pneumonia and alternative treatment for other respiratory infections. These agents are frequently used in patients with penicillin allergies. The macrolides are well-tolerated agents. macrolides are divided into 3 groups for likely occurrence of drug-drug interactions: group 1 (e.g. erythromycin) are frequently involved, group 2 (e.g. clarithromycin, roxithromycin) are less commonly involved, whereas drug interactions have not been described for group 3 (e.g. azithromycin, dirithromycin). Few pharmacoeconomic studies involving macrolides are presently available. The ketolides are being developed in an attempt to address the increasingly prevalent problems of macrolide-resistant and multiresistant organisms.

Yakugaku Zasshi. 2000 Apr; 120(4): 374-86
Matsuoka M

Macrolide antibiotics (Mac) consist of a 12- to 16-membered lactone ring combined with a sugar moiety, and they inhibit protein synthesis via binding to 23S ribosomal RNA in bacteria. The 14- and 16-membered Mac are used for treating infectious diseases caused by Gram-positive and other bacteria; e.g., Haemophilus influenzae, Bordetella pertussis, Legionella pneumophila, Campylobacter, Treponema pallidum and Mycoplasma. Resistance to macrolide, lincosamide, and streptogramin-B (MLS) antibiotics in staphylococci is known to have the following mechanisms: 1) alteration of the target on ribosome due to dimethylation of a specific adenine residue in the 23S ribosomal RNA by the product of the erm gene, and consequently a decrease in binding of MLS antibiotics; 2) inactivation of streptogramin-B (STG-B) and lincosamide by the products of the sbh (encoding streptogramin B hydrolase) and linA' (encoding 3-lincomycin 4-clindamycin O-nucleotidyltransferase) genes, respectively; and 3) active efflux of Mac and STG-B antibiotics determined by the msrA and msrB genes in Staphylococcus epidermidis and Staphylococcus xylosus, respectively, both of which appear to act as an ATP-dependent efflux pump. I have shown that Staphylococcus aureus 8325(pEP2104) exhibits inducible resistance to PMS (partial macrolide and streptogramin B)-antibiotics [the 14-membered macrolides, erythromycin (EM), and oleandomycin (OL), and the 16-membered macrolide mycinamicin (MCM) and STG-B]. The sequence of the N-terminal amino acid residues of a 63 kDa protein (MsrSA) that appeared in the membrane of PMS-resistant strains was identical to that of an MsrA polypeptide related to enhanced efflux of [14C]EM. Ribosomes from PMS-resistant strains showed a similar affinity for EM to those from the PMS-sensitive host strain NCTC8325, and no inactivation of EM by 8325(pEP2104) was observed. In the present study, I showed the DNA sequence of the msrSA region on the constitutive PMS-resistant plasmid pMC38, PMS-inducible resistant plasmid pEP2104 and PMS-sensitive mutant plasmid pSP6, and the region that is essential for inducible expression in PMS resistance. In addition, I investigated the relationship between PMS resistance and intracellular accumulation of EM.

Antimicrob Agents Chemother. 1997 Dec; 41(12): 2719-23
Clancy J, Dib-Hajj F, Petitpas JW, Yuan W

A strain of Streptococcus agalactiae displayed resistance to 14-, 15-, and 16-membered macrolides. In PCR assays, total genomic DNA from this strain contained neither erm nor mef genes. EcoRI-digested genomic DNA from this strain was cloned into lambda Zap II to construct a library of S. agalactiae genomic DNA. A clone, pAES63, expressing resistance to erythromycin, azithromycin, and spiramycin in Escherichia coli was recovered. Deletion derivatives of pAES63 which defined a functional region on this clone that encoded resistance to 14- and 15-membered, but not 16-membered, macrolides were produced. Studies that determined the levels of incorporation of radiolabelled erythromycin into E. coli were consistent with the presence of a macrolide efflux determinant. This putative efflux determinant was distinct from the recently described Mef pump in Streptococcus pyogenes and Streptococcus pneumoniae and from the multicomponent MsrA pump in Staphylococcus aureus and coagulase-negative staphylococci. Its gene has been designated mreA (for macrolide resistance efflux).

Laryngoscope. 1997 Dec; 107(12 Pt 1): 1661-6
Suzuki H, Shimomura A, Ikeda K, Furukawa M, Oshima T, Takasaka T

The mechanism of macrolide therapy in chronic sinusitis patients is unclear. The authors studied the effect of macrolides on interleukin (IL)-8 secretion from cultured human nasal epithelial cells. Epithelial cells harvested from the nasal polyps of patients with chronic sinusitis were primary-cultured, and secreted IL-8 in culture media was measured by enzyme immunoassay. The cells secreted considerable amounts of IL-8 constitutively and in response to lipopolysaccharide. The secretion was significantly inhibited by 10(-5) M of erythromycin, clarithromycin, roxithromycin, and josamycin. 10(-6) M erythromycin still showed the inhibitory effect, whereas the same concentration of josamycin did not. These results indicate that macrolide antibiotics may act as an immunomodulator to reduce IL-8 in inflammatory sites and, at least partially, account for the clinically discrepant effects between 14- and 16-membered ring macrolides in long-term low-dose therapy for chronic sinusitis.

Mol Microbiol. 1996 Dec; 22(5): 867-79
Clancy J, Petitpas J, Dib-Hajj F, Yuan W, Cronan M, Kamath AV, Bergeron J, Retsema JA

Several streptococcal strains had an uncharacterized mechanism of macrolide resistance that differed from those that had been reported previously in the literature. This novel mechanism conveyed resistance to 14- and 15-membered macrolides, but not to 16-membered macrolides, lincosamides or analogues of streptogramin B. The gene encoding this phenotype was cloned by standard methods from total genomic digests of Streptococcus pyogenes 02C1064 as a 4.7 kb heterologous insert into the low-copy vector, pACYC177, and expressed in several Escherichia coli K-12 strains. The location of the macrolide-resistance determinant was established by functional analysis of deletion derivatives and sequencing. A search for homologues in the genetic databases confirmed that the gene is a novel one with homology to membrane-associated pump proteins. The macrolide-resistance coding sequence was subcloned into a pET23a vector and expressed from the inducible T7 promoter on the plasmid in E. coli BL21(DE3). Physiological studies of the cloned determinant, which has been named mefA for macrolide efflux, provide evidence for its mechanism of action in host bacteria. E.coli strains containing the cloned determinant maintain lower levels of intracellular erythromycin when this compound is added to the external medium than isogenic clones without mefA. Furthermore, intracellular accumulation of [14C]-erythromycin in the original S. pyogenes strain was always lower than that observed in erythromycin-sensitive strains. This is consistent with a hypothesis that the gene encodes a novel antiporter function which pumps erythromycin out of the cell. The gene appears to be widely distributed in S. pyogenes strains, as demonstrated by primer-specific synthesis using the polymerase chain reaction.

Biol Pharm Bull. 1993 Dec; 16(12): 1288-90
Matsuoka M, Jánosi L, Endou K, Saitoh S, Hashimoto H, Nakajima Y

A plasmid, pEP2104 (23.9 kilobase pairs), from Staphylococcus aureus carries a gene that specifies inducible resistance to 14-membered (erythromycin, EM, and oleandomycin, OL) and 16-membered macrolide (mycinamicin I and II), but not to all of the latter, and to streptogramin type B antibiotics (partial macrolide- and streptogramin-B-antibiotic resistance: PMS-resistance) (L. Jánosi, E. Bán, Acta Microbiol. Acad. Sci. Hung., 29, 187 (1982) and Y. Nakajima et al., J. Pharmacobio-Dyn., 15, 319 (1992)). The induced cells of strain 8325(pEP2104) did not inactivate EM, OL, josamycin, rokitamycin or mikamycin B (MKM-B), and the cell-free extract of the strain did not inactivate EM or MKM-B, either. Ribosomes from the cells whose PMS-resistance was induced by EM were sensitive not only to EM or spiramycin, but also to MKM-B. A 63000-dalton protein increased to a great extent only in the cell membrane fractions of induced 8325(pEP2104), and may be involved in PMS-resistance.

J Antimicrob Chemother. 1993 Mar; 31 Suppl C: 1-9
Mazzei T, Mini E, Novelli A, Periti P

After the discovery of erythromycin and other natural compounds, including oleandomycin, spiramycin, josamycin and midecamycin, much research has been devoted to synthesizing derivatives or analogues with improved chemical, biological and pharmacokinetic properties. These new macrolides are semisynthetic molecules that differ from the original compounds in their substitution pattern of the lactone ring system. The chemical structure of macrolides is characterized by a large lactone ring containing from 12 to 16 atoms to which are attached, via glycosidic bonds, one or more sugars. The lactone ring is substituted by hydroxyl or alkyl groups, one ketone at C7 in 12-membered macrolides and at C9 in 14-membered macrolides, and one aldehyde group in 16-membered macrolides. The only compound with a 15-membered ring contains a tertiary amino group. Although the 12-membered macrolides have never become important in clinical practice, in recent years numerous new 14-membered macrolide derivatives of erythromycin A have shown improved pharmacokinetics due to chemical modifications of a hydroxyl group at C6, a proton at C8, or a ketone at C9. Derivatives, such as dirithromycin, roxithromycin, clarithromycin and flurithromycin, have all been synthesized with the aim of inhibiting their decomposition under acidic conditions to inactive anhydrohemiketal derivatives. A new 15-membered macrolide, azithromycin, with a methylated nitrogen inserted into the lactone ring shows good activity against Gram-negative bacteria. The efforts expended in chemical and biochemical modifications of 16-membered macrolides have been less successful, with only a few new molecules, such as rokitamycin and miocamycin, showing improved bioavailability and activity against some resistant micro-organisms.(ABSTRACT TRUNCATED AT 250 WORDS)

Appl Environ Microbiol. 1989 Jun; 55(6): 1507-11
Yao RC, Mahoney DF

An enzyme-linked immunosorbent assay was developed for the detection of macrolide antibiotics by using a polyclonal antibody generated in rabbits immunized with 23-amino-O-mycaminosyltylonolide (23-amino-OMT) covalently linked to keyhole limpet hemocyanin. The specificity and sensitivity of this antibody were characterized by using 23-amino-OMT coupled to alkaline phosphatase as an enzyme-linked label in a direct competitive enzyme-linked immunosorbent assay. The assay sensitivity was as low as 0.3 ng/ml for 23-amino-OMT, with a 50% inhibitory concentration of 8 ng/ml. This antibody exhibited good reactivity with 12-, 14- or 16-membered macrolides possessing amino-substituted sugar moieties, regardless of the presence of neutral sugar residues. Little or no cross-reactivity was observed with the macrocyclic lactone ring structure (tylactone) or macrolides containing only neutral sugars. No cross-reaction was observed with polyenes or nonmacrolide antibiotics. Known macrolide-producing cultures grown in fermentation broth also showed good reactivity, indicating that this assay is useful in detecting this class of metabolites in fermentation.

Antimicrob Agents Chemother. 1989 Jan; 33(1): 78-81
Fernandes PB, Baker WR, Freiberg LA, Hardy DJ, McDonald EJ

Macrolide-resistant bacteria can be classified as inducibly resistant or constitutively resistant. Inducibly resistant bacteria are resistant to 14-membered macrolides, such as erythromycin and clarithromycin (A-56268), but are susceptible to the 16-membered macrolides, such as tylosin and spiramycin, as well as to clindamycin. Constitutively resistant bacteria are resistant to macrolide-lincosamide-streptogramin B antibiotics. In this study, the MICs of several erythromycin and clarithromycin analogs against macrolide-susceptible and macrolide-resistant Streptococcus pyogenes strains were determined. Four 11,12-carbamate analogs of clarithromycin had lower MICs than erythromycin did against S. pyogenes with the inducible or constitutive type of macrolide-lincosamide-streptogramin B resistance. Five 11,12-carbonate analogs of erythromycin with modifications at the 4" position of cladinose had lower MICs than did erythromycin against S. pyogenes with the constitutive type of resistance, and one of these compounds, which had a naphthyl-glycyl substitution at the 4" position, had a lower MIC than erythromycin against both the inducibly resistant and constitutively resistant strains. Two analogs of erythromycin with a modification on the 4" position of cladinose had lower MICs than erythromycin did against the constitutively resistant organisms but not against the inducibly resistant organisms. Thus, 14-membered macrolides can be modified so as to confer a low MIC when tested in vitro.

Jpn J Antibiot. 1988 Jul; 41(7): 920-59
Motohiro T, Aramaki M, Oda K, Kawakami A, Tanaka K, Koga T, Fujimoto T, Sakata Y, Yamashita F, Suzuki K

Rokitamycin (RKM), a newly developed macrolide antibiotic with a 16-membered ring, dissolves well under acidic conditions. It has been improved over other macrolides to minimize individual variations in its absorbability. We measured, using the GA-test, variations in gastric acidities of 43 children with ages between 1 to 14 years, and investigated the relationship between gastric acidities and pharmacokinetic values. Also activities (expressed in MICs) of antimicrobial agents were studied against clinically isolated 229 bacterial strains using an inoculum size of 10(6) cells/ml. Tested organisms included Streptococcus pyogenes (77 strains), Streptococcus agalactiae (29), Streptococcus pneumoniae (2), as Gram-positive cocci, and Haemophilus influenzae (1), Haemophilus parainfluenzae (1), Bordetella pertussis (12), Salmonella sp. (4) and Campylobacter jejuni (103) as Gram-negative bacilli. Against stock strains of bacteria, MICs of 10 drugs (RKM, erythromycin (EM), josamycin (JM), midecamycin (MDM), midecamycin acetate (MOM), clindamycin (CLDM), amoxicillin (AMPC), cefaclor (CCL), minocycline, ofloxacin (OFLX] were determined. Against isolates from patients who underwent treatment with RKM, MICs of only 4 drugs (RKM, EM, JM, MOM) were determined. Measurements were made on plasma and urinary concentrations of RKM and its urinary recovery rates after patients including 6 boys with ages between 5 years 1 month and 11 years 6 months were administered with RKM (dry syrup). Two groups of 6 boys were administered between meals with RKM at dose levels of 5 and 10 mg/kg, respectively. Clinical and bacteriological effects of RKM were evaluated for 175 patients including 5 cases of pharyngitis, 3 tonsillitis, 32 pneumonia, 17 mycoplasmal pneumonia, 34 atypical pneumonia, 28 streptococcal infections, 29 Campylobacter enteritis, 4 Salmonella gastroenteritis, and 23 enteritis due to unknown organisms. Five drop-out cases were excluded from the evaluations. In the evaluable cases, an average dose level used was 31.8 mg/kg/day, with a daily dose divided into 3 to 4 administrations and with an average treatment duration of 9 days. Adverse reactions of RKM and its effects on laboratory test values were investigated in these patients including the drop out cases. Obtained results of these studies are summarized below. 1. The GA-test produced pH values indicating that amounts of gastric acid were mostly either normal or high in 42 of the 43 subjects tested (97.7%), and only one low acid case (2.3%) was observed.(ABSTRACT TRUNCATED AT 400 WORDS)