Stereospecific 2'-amination and 2'-chlorination of adenosine by Actinomadura in the biosynthesis of 2'-amino-2'-deoxyadenosine and 2'-chloro-2'-deoxycoformycin.
2'-Amino-2'-deoxyadenosine and 2'-chloro-2'-deoxycoformycin (2'-CldCF) are two nucleoside antibiotics produced by Actinomadura. The biosynthesis of these two nucleoside antibiotics has been studied by the addition of [U-14C]adenosine with or without unlabeled adenine to cultures of Actinomadura. By this experimental approach, it is possible to demonstrate that adenosine is the direct precursor for the biosynthesis of 2'-amino-2'-deoxyadenosine and 2'-CldCF. These conclusions are based on the observation that the percentage distribution of 14C in the aglyconic and pentofuranosyl moieties of 2'-amino-2'-deoxyadenosine and 2'-CldCF were similar to the distribution of 14C in the adenine and ribosyl moieties of the [U-14C]adenosine (i.e., 48:52) added to cultures of Actinomadura. Experimentally, the percentage distribution of 14C in the (i) adenine:2-amino-2-deoxy-beta-D-ribofuranose of 2'-amino-2'-deoxyadenosine is 51:49; (ii) 8-(R)-3,6,7,8-tetrahydroimidazo[4,5-d]-[1,3-diazepin-8-o1]:2 -chloro-2- beta-D-ribofuranose of 2'-CldCF is 45:55; and (iii) adenine:ribose of the adenosine isolated from the RNA of Actinomadura is 42:58. Further proof that adenosine is the direct precursor for the biosynthesis 2'-amino-2'-deoxyadenosine and 2'-CldCF was demonstrated by the addition of 75 mumol of unlabeled adenine together with [U-14C]adenosine to nucleoside-producing cultures of Actinomadura. The percentage distribution of 14C in the aglycon and the sugar moieties of 2'-amino-2'-deoxyadenosine and 2'-CldCF were 46:54 and 47:53, respectively; the percentage distribution of 14C in the adenine and ribose moieties of the adenosine isolated from the RNA of Actinomadura was 51:49. These data show that the hydroxyl on C-2' of the ribosyl moiety of adenosine undergoes a replacement by a 2'-amino or a 2'-chloro group to form 2'-amino-2'-deoxyadenosine or 2'-CldCF with retention of stereconfiguration at C-2'. Finally, Actinomadura can utilize inorganic chloride from the medium as demonstrated by the isolation of [36Cl]2'-CldCF following the addition of [36Cl]chloride to the culture medium. Mechanisms for the regioselective modification of the C-2' hydroxyl group and stereospecific insertion of the amino and chloro groups are discussed.
Suhadolnik
R J
RJ
Department of Biochemistry, Temple University School of Medicine, Philadelphia, Pennsylvania 19140.
Pornbanlualap
S
S
Baker
D C
DC
Tiwari
K N
KN
Hebbler
A K
AK
D000192:Actinomycetales / Q000378:metabolism*; D000241:Adenosine / Q000378:metabolism*; D000586:Amination; D000900:Anti-Bacterial Agents / Q000096:biosynthesis*; D002713:Chlorine / Q000378:metabolism; D003070:Coformycin / Q000031:analogs & derivatives / Q000096:biosynthesis; D003839:Deoxyadenosines / Q000031:analogs & derivatives* / Q000096:biosynthesis; D009705:Nucleosides; D015649:Pentostatin / Q000031:analogs & derivatives*; D011355:Prodrugs / Q000378:metabolism; D013237:Stereoisomerism
D000900:Anti-Bacterial Agents; D003839:Deoxyadenosines; D009705:Nucleosides; D011355:Prodrugs; C003965:2'-amino-2'-deoxyadenosine; D003070:Coformycin; D015649:Pentostatin; D002713:Chlorine; C046686:adechlorin; D000241:Adenosine