Catabolite repression in Streptomycin-dependent Escherichia coli
department or school: Medicine, Faculty of
department or school: Biochemistry and Molecular Biology, Department of
data provider: DSpace
degree campus: UBCV
creator: Coukell, Milton Barrie
issued: 2011-07-16T22:05:50Z
issued: 1969
related degree: Doctor of Philosophy - PhD
degree grantor: University of British Columbia
description: Biosynthetic reactions in micro-organisms normally are under precise control, usually by a feed-back mechanism in which the end product inhibits the activity and/or represses the formation of the enzyme which initiates the biosynthetic pathway. Streptomycin (Sm)-dependent mutants of Escherichia coli, unlike the parent wild-type strains excrete the amino acid, L-valine, thereby indicating a loss of precise regulation in the biosynthesis of this amino acid (Tirunarayanan, Vischer and Renner, 1962; Bragg and Polglase, 1962). The initiating enzyme for valine biosynthesis, acetohydroxy acid (AHA) synthetase, is derepressed in Sm-dependent E. coli (Coukell and Polglase, 1965), thus providing an explanation for the excretion of valine by this mutant. However, it was apparent that the extent and cause of regulatory insufficiency in Sm-dependent E. coli required further investigation. A study of the effect of the carbon source used for growth on AHA synthetase formation revealed that in wild-type E. coli B this enzyme was subject to catabolite repression. End-product inhibition of AHA synthetase by L-valine in E. coli B attained a maximum at 60-70% inhibition. These previously unreported properties of AHA synthetase (sensitivity to catabolite repression and incomplete end-product inhibition) are significant in the regulation of the biosynthetic pathway leading to the aliphatic amino acids and pantothenate. In Sm-dependent E. coli B, growing with non-limiting antibiotic, catabolite repression of AHA synthetase was relaxed. Additional evidence for relaxation of catabolite repression in Sm-dependent E. coli was provided by the observation that Sm-dependent mutants of E. coli (strains B and E) were inducible for β-galactosidase in the presence of glucose Furthermore, several glucose-sensitive enzymes of wild-type E. coli B (citrate synthase, fumarase, aconitase and iso-citrate dehydrogenase) were found to be insensitive to variation in the nature of the carbon source in a Sm-dep…
aggregated CHO: https://circle.library.ubc.ca/rest/handle/2429/36049
note: CATABOLITE REPRESSION IN STREPTOMYCIN-DEPENDENT ESCHERICHIA COLI by MILTON BARRIE COUKELL B . S c , U n i v e r s i t y o f B r i t i s h C o l u m b i a , 1963 M.Sc., U n i v e r s i t y o f B r i t i s h C o l u m b i a , 1966 A THESIS SUBMITTED IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY i n t h e Department of BIOCHEMISTRY We a c c e p t t h i s t h e s i s as c o n f o r m i n g t o the r e q u i r e d s t a n d a r d T/flE UNIVERSITY OF A p r i l , BRITISH COLUMBIA 1969 In p r e s e n t i n g t h i s t h e s i s i n p a r t i a l f u l f i l m e n t o f the r e q u i r e m e n t s f o r an advanced degree a t the U n i v e r s i t y o f B r i t i s h C olumbia, I ag r e e t h a t the L i b r a r y s h a l l make i t f r e e l y a v a i l a b l e f o r r e f e r e n c e and Study. I f u r t h e r a g r e e t h a t p e r m i s s i o n f o r e x t e n s i v e c o p y i n g of t h i s t h e s i s f o r s c h o l a r l y purposes may be g r a n t e d by the Head o f my Department or by h i s r e p r e s e n t a t i v e s . I t i s u n d e r s t o o d t h a t c o p y i n g or p u b l i c a t i o n of t h i s t h e s i s f o r f i n a n c i a l g a i n s h a l l not be a l l o w e d w i t h o u t my w r i t t e n p e r m i s s i o n . Department of // C L ^ O e y - C ^ K ^ K ^ L - ^ X / S-y The U n i v e r s i t y o f B r i t i s h Columbia Vancouver 8, Canada Date i ABSTRACT B i o s y n t h e t i c r e a c t i o n s i n m i c r o - o r g a n i s m s n o r m a l l y a re under p r e c i s e c o n t r o l , u s u a l l y by a feed-back mechanism i n whi c h t h e end p r o d u c t i n h i b i t s t he a c t i v i t y and/or r e p r e s s e s the f o r m a t i o n o f t h e enzyme which i n i t i a t e s t he b i o s y n t h e t i c pathway. S t r e p t o m y c i n (Sm)-dependent mutants o f Escherichia c o l i , u n l i k e t h e p a r e n t w i l d - t y p e s t r a i n s e x c r e t e the amino a c i d , L - v a l i n e , t h e r…
has type: Thesis/Dissertation
is shown at: 10.14288/1.0104323
language: eng
degree discipline: Biochemistry and Molecular Biology
provider: Vancouver : University of British Columbia Library
publisher: University of British Columbia
rights: For non-commercial purposes only, such as research, private study and education. Additional conditions apply, see Terms of Use https://open.library.ubc.ca/terms_of_use.
scholar level: Graduate
type: Text
identifier URI: http://hdl.handle.net/2429/36049