RESUMO
The nitrogen-fixing, symbiotic root-nodule forming bacterium Bradyrhizobium japonicum USDA 110 contained gammacerane derivatives next to triterpenoids of the hopane series. Diploptene, diplopterol, 2 beta-methyldiplopterol, aminobacteriohopanetriol and adenosylhopane were accompanied by tetrahymanol and the corresponding novel methylated homologues 2 beta-methyltetrahymanol, 20 alpha-methyltetrahymanol, and 2 beta,20 alpha-dimethyltetrahymanol. Incorporation of [(2)H(3)]methyl-L-methionine indicated that the additional methyl groups originated from methionine, probably with S-adenosylmethionine acting as methyl donor, with retention of the three deuterium atoms. The simultaneous presence of hopane and gammacerane derivatives seems a characteristic feature of the genus Bradyrhizobium and the phylogenetically closely related Rhodopseudomonas palustris.
Assuntos
Bradyrhizobium/química , Triterpenos/metabolismo , Bradyrhizobium/metabolismo , Cromatografia em Camada Fina , Ciclização , Deutério/metabolismo , Cromatografia Gasosa-Espectrometria de Massas , Liases/metabolismo , Espectroscopia de Ressonância Magnética , Metionina/análogos & derivados , Metionina/metabolismo , Metilação , Filogenia , Fosfatos de Poli-Isoprenil/metabolismo , Rodopseudomonas/química , Rodopseudomonas/metabolismo , S-Adenosilmetionina/metabolismo , Simbiose , Triterpenos/químicaRESUMO
Streptomyces coelicolor A3(2) contains a cluster of putative isoprenoid and hopanoid biosynthetic genes. The strain does not produce the pentacyclic hopanoids in liquid culture but produces them on solid medium when sporulating. Mutants defective in the formation of aerial mycelium and spores (bld), with the exception of bldB, do not synthesize hopanoids, whereas mutants, which form aerial mycelium but no spores (whi), do. The membrane condensing hopanoids possibly may alleviate stress in aerial mycelium by diminishing water permeability across the membrane.
