Folate-dependent enzymes in cultured Chinese hamster ovary cells: evidence for mutant forms of folylpolyglutamate synthetase
A Chinese hamster ovary auxotroph requiring glycine + adenosine + thymidine CHO AUXB1) was shown by us previously to lack several folylpolyglutamate synthetase (FPGS) type activities. Two revertants of AUXB1 have been isolated and found to contain altered forms of this enzyme. The revertant enzymes are more sensitive to heat inactivation than the parent CHO enzyme. ATP and MgCl/sub 2/ protect both revertant and parent CHO FPGS against rapid heat denaturation at pH 9.0, but not at pH 7.4. A genetically related auxotroph (CHO AUXB3) contains one-fifth the parent amount of FPGS. Unlike the FPGS from parent CHO and a genetically unrelated mutant requiring only glycine (CHO AUXB2), the AUXB3 enzyme specifically lacks tetrahydropteroyltetra(U-/sup 14/C)glutamate synthetase activity. These findings and polyethylene glycol fusion data with AUXB2 indicate that AUXB1 and AUXB3 each carry a mutation in the structural gene for a CHO FPGS that catalyzes tetrahydropteroyldi- as well as tetraglutamate formation. The altered form of FPGS in AUXB3 is responsible for its glycine + adenosine auxotrophy under standard culture conditions.
- Research Organization:
- Lawrence Livermore Lab., CA
- DOE Contract Number:
- W-7405-ENG-48
- OSTI ID:
- 6864803
- Journal Information:
- Arch. Biochem. Biophys.; (United States), Vol. 197:1
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
ANIMAL CELLS
MUTANTS
ENZYME ACTIVITY
COMPARATIVE EVALUATIONS
LIGASES
CARBON 14 COMPOUNDS
FOLIC ACID
GLUTAMIC ACID
HAMSTERS
HEAT
INACTIVATION
REVERTANTS
AMINO ACIDS
ANIMALS
CARBOXYLIC ACIDS
DRUGS
ENERGY
ENZYMES
HEMATINICS
HEMATOLOGIC AGENTS
HETEROCYCLIC COMPOUNDS
HYDROXY COMPOUNDS
LABELLED COMPOUNDS
MAMMALS
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
PTERIDINES
RODENTS
VERTEBRATES
VITAMIN B GROUP
VITAMINS
550400* - Genetics