The Catabolism of Cystathionine by Escherichia coli

Wijesundera, S.; Woods, D. D.

doi:10.1099/00221287-29-2-353

Cited by 26 publications

(9 citation statements)

References 26 publications

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“…I n the present case cysteine desulphydrase (deaminase) activity disappeared and reappeared in parallel with that of cystathionase; this and other evidence led to the conclusion that both activities are a function of the same protein. On the other hand, D-serine dehydratase (deaminase) activity was not affected when cystathionine was repressed or resynthesized; this supports the conclusion of Wijesundera & Woods (1962), based on purification and selective inactivation, that the enzymes which attack D-serine and cystathionine are distinct entities.…”

Section: '7supporting

confidence: 70%

“…Earlier experiments in this laboratory on the cystathionase of Escherichia coli (Wijesundera & Woods, 1962) were made with a pyridoxin auxotroph (~1 6 6 ) and a wild strain ( F ) ; furthermore the cell-free extracts then used were prepared by shaking with minute glass balls. It was first necessary to establish that the strain…”

Section: Cystathionase Activity Of Various Strains Of Escherichia Colimentioning

confidence: 99%

“…The microbiological method described by Wijesundera & Woods (1962) with Escherichia coli strain 26/18 (which responds to homocysteine and methionine) was used, as was the chromatographic procedure used by those authors.…”

Section: Extract Of Heated Escherichia Coli (Strain ~~1 5 )mentioning

confidence: 99%

“…The L-cystathionine used was the batch described by Wijesundera & Woods (1962) isolated from the mycelium of a mutant of Neurospora crassa. DLAllocystathionine was obtained from the California Corporation for Biochemical Research (Los Angeles, U.S.A.).…”

Section: Extract Of Heated Escherichia Coli (Strain ~~1 5 )mentioning

confidence: 99%

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Repression by Methionine of Cystathionase Formation in Escherichia coli

Rowbury

Woods

1964

Journal of General Microbiology

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SUMMARYCystathionase catalyses the formation of homocysteine from cystathionine; its formation in cultures of Escherichia coli is repressed by the presence of methionine in the growth medium, and to a similar extent to that shown with homocysteine methylase (the enzyme complex which catalyses the conversion homocysteine -+ methionine). Cystathionase, again like homocysteine methylase, is formed rapidly without concomitant growth when repressed organisms are transferred to a medium free from methionine ; such enzyme formation is prevented by chloramphenicol, suggesting that de novo synthesis of protein is required. The co-repression by methionine of the two enzyme systems fortifies the evidence that cystathionase is a component of the normal pathway of methionine synthesis by E . coli and consequently that its substrate, cystathionine, is a normal intermediate. Cystathionase preparations also formed pyruvate from cysteine; this activity paralleled that of cystathionase itself when the methionine status of the medium was changed, and it is concluded that the same protein is responsible for both activities. INTRODUCTIONIn previous work in this laboratory Wijesundera & Woods (1962) showed that L-cystathionine was converted to homocysteine, pyruvate and ammonia by a cystathionase enzyme present in several strains of Escherichia coli. Since homocysteine is undoubtedly the immediate precursor of methionine in this organism (see review by Guest & Woods, 1962), these observations supported the view, originating from the properties of methionine auxotrophs of 23. coli and other micro-organisms, that cystathionine is an earlier intermediate, though there remained some evidence to the contrary (see Discussion). The final reaction by which homocysteine is converted to methionine is a complicated one requiring folic acid derivatives and, in certain circumstances, also cobalamin as cofactors (Guest & Woods, 1962). However, the formation of the enzyme complex (homocysteine methylase), and indeed individual components of it, is repressed by the presence of methionine in the culture medium; the enzymes are, however, rapidly resynthesized when methionine is removed (Rowbury & Woods, 1961 ; Foster, Rowbury & Woods, 1963). The main objective of the present work was to examine the effect of growth with methionine on the cystathionase content of E. coli with conditions under which it could be strictly compared with the known effect on the homoc ys t eine met hy lase complex. TO Xhcrob. xxxvDownloaded from www.microbiologyresearch.org by

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Section: '7supporting

confidence: 70%

Section: Cystathionase Activity Of Various Strains Of Escherichia Colimentioning

confidence: 99%

Section: Extract Of Heated Escherichia Coli (Strain ~~1 5 )mentioning

confidence: 99%

Section: Extract Of Heated Escherichia Coli (Strain ~~1 5 )mentioning

confidence: 99%

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Repression by Methionine of Cystathionase Formation in Escherichia coli

Rowbury

Woods

1964

Journal of General Microbiology

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“…Results obtained support the existence of the 5 methionine genes originally identified (metA, B, C, E and F) and have revealed another (metG). Parallel work on the enzyme deficiencies of similar Escherichia coli mutants and representative S. tphimurium mutants (Rowbury, 1964a, b; Rowbury and Woods, 1964;Wijesundera and Woods, 1962;Woods, Foster and Guest, 1965;Foster, personal communication) has permitted the firm establishment of the same pathway of methionine synthesis in these two organisms ( fig. ).…”

Section: Discussion (I) the Genes And Enzymes Concerned With Methionimentioning

confidence: 99%