1887

Abstract

SUMMARY: Two non-allelic suppressors have been isolated which suppress non-allelic, leaky, methionine-requiring mutants blocked either between cysteine and cystathionine or between cystathionine and homocysteine. Strains carrying either suppressor gene in the presence of the allele were stimulated by either cysteine or methionine, whereas the suppressed methionine-requiring mutants () although stimulated by methionine were inhibited by cysteine. S-methylcysteine supported the growth of leaky methionine-requiring mutants when it was present as the sole sulphur source and it also stimulated the growth of suppressed methionine-requiring mutants inhibited by cysteine. Sulphate or cysteine inhibited the growth response of certain methionine-requiring mutants to S-methylcysteine. The incorporation of radioactive sulphate into protein methionine was inhibited to a greater extent by S-methylcysteine than was its incorporation into protein cysteine. The results suggest that the sulphur of S-methylcysteine is converted to methionine without prior conversion to cysteine and that the suppressors act by retarding the formation of an inhibitor which accumulates as a result of the primary mutation to methionine requirement.

Loading

Article metrics loading...

/content/journal/micro/10.1099/00221287-28-3-481
1962-07-01
2019-10-14
Loading full text...

Full text loading...

http://instance.metastore.ingenta.com/content/journal/micro/10.1099/00221287-28-3-481
Loading
This is a required field
Please enter a valid email address
Approval was a Success
Invalid data
An Error Occurred
Approval was partially successful, following selected items could not be processed due to error