Mutant strains of Rhodopseudomonas spheroides lacking delta-aminolevulinate synthase: growth, heme, and bacteriochlorophyll synthesis.
Two mutant strains of Rhodopseudomonas spheroides were described which lacked delta-aminolevulinate synthase activity. They required delta-aminolevulinate for growth; they did not respond to protoporphyrin or magnesium photoporphyrin, and only poorly to hemin. Synthesis of cytochromes and heme by mutant H-4 was dependent upon delta-aminolevulinate; this strain did not form bacteriochlorophyll either with or without delta-aminolevulinate and, consequently, grew only under aerobic conditions. Mutant H-5 formed bacteriochlorophyll in response to delta-aminolevulinate and grew both anaerobically in the light and aerobically in the dark; the amount of delta-aminolevulinate needed for optimal anaerobic growth was higher than that required aerobically. Synthesis of bacteriochlorophyll and heme by suspensions of mutant H-5 incubated anaerobically in the light was dependent upon delta-aminolevulinate; bacteriochlorophyll production was completely inhibited by high aeration and by puromycin. The mutants differed in their ability to take up radioactive delta-aminolevulinate from the external environment; mutant H-5 was less active than mutant H-4 or the wild type. It was suggested that R. spheroides made only one form of delta-aminolevulinate synthase, which provided delta-aminolevulinate for bacteriochlorophyll and heme synthesis.
D000217:Acyltransferases; D000596:Amino Acids; D001375:Azaguanine / Q000494:pharmacology; D002247:Carbon Isotopes; D002734:Chlorophyll / Q000096:biosynthesis*; D006418:Heme / Q000096:biosynthesis*; D007503:Iron Isotopes; D007982:Levulinic Acids; D009154:Mutation; D011691:Puromycin / Q000494:pharmacology; D011758:Pyrroles / Q000096:biosynthesis; D012241:Rhodopseudomonas / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism; D013912:Threonine / Q000494:pharmacology
D000596:Amino Acids; D002247:Carbon Isotopes; D007503:Iron Isotopes; D007982:Levulinic Acids; D011758:Pyrroles; D002734:Chlorophyll; D013912:Threonine; D006418:Heme; D011691:Puromycin; D000217:Acyltransferases; D001375:Azaguanine