Comparative metabolism of Chlamydia with special reference to catabolic activities

Deoxyribonucleic acid-dependent ribonucleic acid polymerase activity in purified trachoma elementary bodies: effect of sodium chloride on ribonucleic acid transcription

Highly purified trachoma elementary bodies (T'ang strain), incubated in the presence of the four nucleoside triphosphates [Mg(2+), Mn(2+), 2-mercaptoethanol, tris(hydroxymethyl)aminomethane buffer (pH 7.5)] were found to incorporate (3)H-uridine triphosphate (UTP) into ribonucleic acid (RNA) molecules. Eighty-seven per cent of the labeled molecules were sensitive to ribonuclease treatment. In vitro RNA synthesis was almost completely inhibited by actinomycin D. Rifampin was also inhibitory, but allowed some initial RNA synthesis before complete inhibition occurred. When the reaction mixture lacked Mn(2+), trachoma elementary bodies synthesized, for a limited period, high-molecular-weight RNA species (23 to 24S, 16 to 17S, and 10 to 11S). Addition of 0.2 m NaCl to the same reaction mixture stimulated and prolonged (3)H-UTP incorporation into the same radioactive RNA species. Addition of 0.001 m Mn(2+) instead of NaCl also stimulated (3)H-UTP incorporation but prevented the synthesis of the high-molecular-weight RNA species.

Lipid synthesis by isolated Chlamydia psittaci

The isolated cells of the host-dependent meningopneumonitis agent, Chlamydia psittaci, were shown to incorporate radioactive carbon from aspartate, isoleucine, and glucose-6-phosphate into cell lipids. The nature of this incorporation was investigated. Radioactivity was found only in the fatty acids and primarily in the phosphatidyl ethanolamine, and, to a lesser extent, in the phosphatidyl choline fractions. Branched-chain fatty acids, not found in host lipid, were shown to constitute a large proportion of the fatty acid content of phosphatidyl ethanolamine. The reasons why only fatty acid synthesis took place under the conditions of our experiments with isolated meningopneumonitis agent cells remain obscure.

Role of exogenous adenosine triphosphate in catabolic and synthetic activities of Chlamydia psittaci

The synthetic activities of isolated cells of the meningopneumonitis strain (MN) of Chlamydia psittaci were investigated and further observations were made on their catabolic reactions. These observations included the demonstration of CO(2) production from aspartate in the presence of pyruvate and the formation of pyruvate from glucose-6-phosphate. Both reactions were enhanced by added adenosine triphosphate (ATP). Of a large number of compounds tested, only glucose-6-phosphate, pyruvate, aspartate, and isoleucine were shown to furnish carbons that were incorporated into molecules precipitated by trichloroacetic acid. The reactions with pyruvate, aspartate, and isoleucine were dependent entirely, or almost entirely, on added ATP, and the reaction with glucose-6-phosphate was enhanced by ATP. Except for CO(2), which greatly stimulated the reactions, the addition of a number of other compounds or a combination of compounds, such as cofactors, amino acids, and purine and pyrimidine bases, did not greatly affect incorporation. About 95% of the activity of the trichloroacetic acid precipitates was recovered in the chloroform-methanol soluble fraction.

Influence of gas environment on catabolic activities and on reoxidation of reduced nicotinamide adenine dinucleotide phosphate in Chlamydia

We investigated the effect of the gas environment on the enzymatic reactions of intact isolated cells of the agents of trachoma and of meningopneumonitis of the host-dependent genus Chlamydia. In comparison with the reactions taking place in a gas phase of air, O(2) depressed CO(2) production from pyruvate and glutamate by trachoma and from glutamate by meningopneumonitis. O(2) enhanced the degradation of pyruvate by meningopneumonitis, but this effect was due to increased H(2)O(2), and was reversed by added catalase. Both dehydrogenation of alpha-ketoglutarate and was reversed by added catalase. Dehydrogenation of alpha-ketoglutarate by both agents and production of CO(2) from C(1) of glucose-6-phosphate were stimulated by O(2) and depressed in N(2). The latter activity was stimulated in air, O(2), and N(2) by nicotinamide adenine dinucleotide phosphate (NADP) in relation to the amount added, and also in air or O(2), but not in N(2), by moderate amounts of NADP and an excess of oxidized glutathione with concomitant formation of H(2)O(2). A small but significant amount of O(2) was consumed during the course of these reactions. It is suggested that glutathione reductase activity can occur only when accompanied by an oxidative reaction, and that this close link between the two reactions represents a mechanism of electron transport which transfers hydrogen to molecular O(2).