Effects of nucleic acid compounds on viability and cell composition of Bdellovibrio bacteriovorus during starvation

Hespell, Robert B.; Mertens, M.

doi:10.1007/bf00406030

Cited by 8 publications

(17 citation statements)

References 16 publications

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“…bacteriovorus clearly possesses the complete potential for degrading ribonucleoside monophosphates and metabolizing the ribose derived from these compounds. This conclusion is best supported by the presence of various enzyme activities in cell extracts (Table 6) and by the previous findings that only the ribose moiety of exogenous ribonucleoside monophosphates is catabolized to C02 by free bdellovibrio cell suspensions (10). It is well established that E. coli also possesses these enzymes (1,6,15,16,20,23,25,28).…”

Section: Discussionmentioning

confidence: 70%

“…With intraperiplasmically growing bdello- (Table 4); (ii) with intraperiplasmic bdellovibrio growth on "4C-labeled nucleic acid base-labeled E. coli, very little radioactivity is detected in the respired C02 and almost all of the radioactivity incorporated into the progeny bdellovibrios is found in the nucleic acid cell fraction (10,11,24); and (iii) when free bdellovibrio cell suspensions are incubated with ribonucleoside monophosphates, only the ribose portion of these compounds is catabolized, with equivalent levels of nucleic acid bases found in the suspending buffer after incubation (10).…”

Section: Discussionmentioning

confidence: 99%

“…From several standpoints, the bdellovibrio metabolism of RNA-ribose is a rather unusual type of bacterial metabolism. Although B. bacteriovorus has the enzymatic potential to metabolize ribose, whole cells do not take up ribose per se or use other exogenous sugars (10,12). Bdellovibrio use of ribose requires that this compound be supplied in the form of ribonucleoside monophosphates which are taken up intact.…”

Section: Discussionmentioning

confidence: 99%

“…The diluted cultures were incubated for 1 h, the appropriate compound(s) for radioactive labeling was added, and incubation was continued for 2 to 3 h (about 6 x 108 cells per ml, final concentration). The compounds used for radioactive labeling included: [5,6-3H]uracil, 0.2 to 0.3 ,uCi/ml, 10 All bdellovibrio and E. coli cultures were harvested by centrifugation, and cell suspensions were made in 5 mM N-2-hydroxyethyl piperazine-N'-ethanesulfonic acid (pH 7.6) containing 0.1 mM MgCl2 and 0.1 mM CaC12 (HM buffer) after two washings by centrifugation in this buffer. Cell numbers in these suspensions were standardized by optical density measurements (660 nm) using reference curves based on plaque counts for bdellovibrio or plate counts for E. coli (38).…”

Section: Methodsmentioning

confidence: 99%

“…Thin-layer chromatography. The procedures outlined by Randerath and Randerath (29) using the solvent systems described previously (10,11) Radioactivity and miscellany. All radioactivity measurements were made by scintillation counting using Aquasol II fluid (New England Nuclear Corp., Boston, Mass.).…”

Section: Methodsmentioning

confidence: 99%

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Metabolism of RNA-ribose by Bdellovibrio bacteriovorus during intraperiplasmic growth on Escherichia coli

Hespell¹,

Odelson²

1978

J Bacteriol

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During intraperiplasmic growth of Bdellovibrio bacteriovorus 109J on Escherichia coli some 30 to 60% of the initial E. coli RNA-ribose disappeared as cellassociated orcinol-positive material. The levels of RNA-ribose in the suspending buffer after growth together with the RNA-ribose used for bdellovibrio DNA synthesis accounted for 50% or less of the missing RNA-ribose. With intraperiplasmic growth in the presence of added U-14C-labeled CMP, GMP, or UMP, radioactivity was found both in the respired C02 and incorporated into the bdellovibrio cell components. The addition of exogenous unlabeled ribonucleotides markedly reduced the amounts of both the 1'CO2 and '4C incorporated into the progeny bdellovibrios. During intraperiplasmic growth of B. bacteriovorus on [U-'4C]ribose-labeled E. coli BJ565, ca. 74% and ca. 19% of the initial 14C was incorporated into the progeny bdellovibrios and respired C02, respectively. Under similar growth conditions, the addition of glutamate substantially reduced only the 14CO2; however, added ribonucleotides reduced both the 14CO2 and the 14C incorporated into the progeny bdellovibrios. No similar effects were found with added ribose-5-phosphate. The distribution of 14C in the major cell components was similar in progeny bdellovibrios whether obtained from growth on [U-14C]ribose-labeled E. coli BJ565 or from E. coli plus added U-_4C-labeled ribonucleotides. After intraperiplasmic growth of B. bacteriovorus on [5,6-3H-]uracil-[U-'4C]ribose-labeled E. coli BJ565 (normal or heat treated), the whole-cell 14C/3H ratio of the progeny bdellovibrios was some 50% greater and reflected the higher 14C/3H ratios found in the cell fractions. B. bacteriovorus and E. coli cell extracts both contained 5'-nucleotidase, uridine phosphorylase, purine phosphorylase, deoxyribose-5-phosphate aldolase, transketolase, thymidine phosphorylase, phosphodeoxyribomutase, and transaldolase enzyme activities. The latter three enzyme activities were either absent or very low in cell extracts prepared from heat-treated E. coli cells. It is concluded that during intraperiplasmic growth B. bacteriovorus degrades some 20 to 40% of the ribonucleotides derived from the initial E. coli RNA into the base and ribose-l-phosphate moieties. The ribose-1phosphate is further metabolized by B. bacteriovorus both for energy production and for biosynthesis, of non-nucleic acid cell material. In addition, the data indicate that during intraperiplasmic growth B. bacteriovorus can metabolize ribose only if this compound is available to it as the ribonucleoside monophosphate.

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