The obligatory involvement of the electron transport system in the catabolic metabolism of Haemophilus parainfluenzae

Oxidation and reduction of membrane-bound cytochrome c in Hemophilus parainfluenzae. Reaction with oxygen, hydrogen peroxide and nitrate

Cytochromes of the a-, b-, c- and d-type become reduced when intact cells of Hemophilus parainfluenzae have become anaerobic following respiration with substrates such as formate or succinate, as shown previously (J. Biol. Chem. (1970) 254, 5096-5100). In the presence of formate after depletion of O2, there is an unusual two-step time course of reduction of the membrane-bound cytochrome c. The proportion of the cytochrome c which is reduced during the second stage is oxidizable by either nitrate or H2O2 and is reduced again when the nitrate or H2O2 have been depleted. We conclude that the observed two-stage reduction of cytochrome c results from the presence of an oxidant, probably H2O2, produced by reaction of formate dehydrogenase with O2. This was shown by the effects of cyanide, catalase and O2. In addition, no evidence for the production of the oxidant is seen when succinate is the substrate oxidized. Although measurements of absorption spectra indicated only one species of cytochrome c, kinetic evidence is presented for some separation of the cytochrome c into more than one electron transport pathway.

Energy metabolism of some representatives of the Haemophilus group

The purpose of this investigation was to characterize the carbohydrate catabolism and the constellation of the respiratory chain components of Haemophilus influenzae RAMC 18 Bensted, H. parainfluenzae 1 Fleming, H. parainfluenzae 429 Pittman and H. aegyptius 180a Pittman. These strains represent several physiological types with respect to respiratory quinones and glucose catabolism. On addition of glucose or lactate to the complex growth medium a remarkable increase in cell mass was observed. Depending on the growth rate, carbohydrate degradation varied with the strains examined so that at the end of the exponential growth phase only small amounts of the supplements could be demonstrated. All strains were found to possess functional enzymes of Embden-Meyerhof-Parnas-, Entner-Doudoroff-pathways, hexosemonophosphate shunt, tricarboxylic acid cycle and gluconeogenesis with an extremely high activity of malate dehydrogenase. The concentration of cytochromes varied according to culture conditions. The cytochromes a1, d, o and b + c were found to occur under aerobic conditions. In cells grown anaerobically in the presence of fumarate cytochromes a1 and d could not be demonstrated. Under aerobic conditions preparations of H. parainfluenzae 1 Fleming exhibited an alpha-maximum at 558 nm, whereas under anaerobic culture conditions with fumarate as terminal electron acceptor an alpha-maximum at 552 nm occurred, suggesting different roles of b and c type cytochromes in aerobic and anaerobic electron transport to fumarate, respectively.

Release of membrane components from viable Haemophilus parainfluenzae by ethylenediaminetetraacetic acid-tris(hydroxymethyl)-aminomethane

Logarithmically growing Haemophilus parainfluenzae lost 15 to 20% of the phospholipids, demethyl vitamin K(2), cytochrome b, and cytochrome c, and 50% of the lipopolysaccharide when incubated in ethylenediaminetetraacetic acid (EDTA)-tris-(hydroxymethyl)aminomethane (Tris) for 10 min. This loss of membrane components occurred without loss in viability, and the lost components were recovered as membrane fragments in the surrounding buffer. The phospholipids recovered in the membrane fragments had a slightly lower specific activity than the phospholipids in the residue. Lysis of a portion of the cells could not account for the release of membrane components, as the cells lost neither glucose-6-phosphate dehydrogenase activity not deoxyribonucleic acid. The treated cells were osmotically stable and contained the same proportions of the individual phospholipids as pretreatment cells. Prolongation of the EDTA-Tris treatment did not induce further loss of phospholipid or demethyl vitamin K(2), but caused a decrease in viability. If the cells were returned to the growth medium after 10 min, the cells immediately resumed growth at the pretreatment rate. During growth in the recovery period, the phospholipids increased logarithmically in the pretreatment rate. During growth in the recovery period, the phospholipids increased logarithmically in the pretreatment proportions, although there was a marked decrease in the turnover and a shift from the use of extracellular lipid precursors to the use of intracellular pools of precursors.

Effect of nitrate, fumarate, and oxygen on the formation of the membrane-bound electron transport system of Haemophilus parainfluenzae

The composition of the membrane-bound electron transport system of Haemophilus parainfluenzae underwent modification in response to the terminal electron acceptor in the growth medium. H. parainfluenzae was able to grow with O(2), nitrate, fumarate, pyruvate, and substrate amounts of nicotinamide adenine dinucleotide (NAD) as electron acceptors. When O(2) served as the electron acceptor and its concentration was lowered below 20 mum, the bacteria formed more cytochromes b, c, a(1), a(2), and o than were present in the cells grown at 150 to 200 mum O(2). Nitrate and nitrite reductase activities also appeared during growth at the low O(2) concentrations in the absence of added nitrate. Cytochrome levels in cells grown anaerobically with fumarate, pyruvate, or NAD as terminal acceptors were similar to those formed in cells grown at low O(2) concentrations. Cells grown with nitrate had higher levels of cytochromes c, b, and o, and of nitrate and nitrite reductases, than did cells grown with the other acceptors. The formation of cytochrome oxidase a(2) was repressed by the presence of nitrate in the growth medium. The critical O(2) concentration (the O(2) concentration at which the rate of O(2) uptake becomes demonstrably dependent on the O(2) concentration) was about 100 mum in cells grown with nitrate and about 15 mum in cells grown with the other acceptors. A mutant of H. parainfluenzae was found to make about 10% as much cytochrome c as the wild type, and its formation of cytochrome a(2) was not repressed by nitrate. The critical O(2) concentration of the mutant was high when it was grown with nitrate, suggesting that the high levels of cytochrome c and the absence of cytochrome a(2) from the wild type are not responsible for the high critical O(2) concentration. The modifications of the respiratory system induced by changing the terminal electron acceptor were inhibited by the presence of chloramphenicol, which suggests that protein synthesis is involved.

Lipid composition of the electron transport membrane of Haemophilus parainfluenzae

The principal lipids associated with the electron transport membrane of Haemophilus parainfluenzae are phosphatidylethanolamine (78%), phosphatidylmonomethylethanolamine (0.4%), phosphatidylglycerol (18%), phosphatidylcholine (0.4%), phosphatidylserine (0.4%), phosphatidic acid (0.2%), and cardiolipin (3.0%). Phospholipids account for 98.4% of the extractible fatty acids. There are no glycolipids, plasmalogens, alkyl ethers, or lipo amino acid esters in the membrane lipids. Glycerol phosphate esters derived from the phospholipids by mild alkaline methanolysis were identified by their staining reactions, mobility on paper and ion-exchange column chromatography, and by the molar glycerol to phosphate ratios. Eleven diacyl phospholipids can be separated by two-dimensional thin-layer chromatography. Each lipid served as a substrate for phospholipase D, and had a fatty acid to phosphate ratio of 2:1. Each separated diacyl phospholipid was deacylated and the glycerol phosphate ester was identified by paper chromatography in four solvent systems. Of the 11 separated phospholipids, 3 were phosphatidylethanolamines, 2 were phosphatidylserines, and 2 were phosphatidylglycerols. Phosphatidylcholine, cardiolipin, and phosphatidic acid were found at a single location. Phosphatidylmonomethylethanolamine was found with the major phosphatidylethanolamine. Three distinct classes of phospholipids are separable according to their relative fatty acid compositions. (i) The trace lipids consist of two phosphatidylethanolamines, two phosphatidylserines, phosphatidylcholine, phosphatidic acid, and a phosphatidylglycerol. Each lipid represents less than 0.3% of the total lipid phosphate. These lipids are characterized by high proportions of the short (C(10) to C(14)) and long (C(19) to C(22)) fatty acids with practically no palmitoleic acid. (ii) The major phospholipids (93% of the lipid phosphate) are phosphatidylethanolamine, phosphatidylmonomethylethanolamine, and phosphatidylglycerol. These lipids contain a low proportion of the short (<C(14)) and long (>C(19)) fatty acids. Palmitic and palmitoleic acids represent over 80% of the total fatty acids. (iii) The fatty acid composition of the cardiolipin is intermediate between the other two classes. Both palmitoleic and the longer fatty acids represent a significant proportion of the total fatty acid.

Electron transport system of the protoheme-requiring anaerobe Bacteroides melaninogenicus

Protoheme is essential for the growth of some strains of Bacteroides melaninogenicus. At low concentrations in the growth medium, protoheme determines the doubling time, total cell yield, and amount of cytochrome per bacterium. At high protoheme concentrations, the doubling time, total cell yield, and amount of enzymatically reducible cytochrome appear to remain nearly constant, and protoheme is accumulated by the cell. The accumulated protoheme can support the growth of the bacterium for at least eight generations in a protoheme-free medium. When growth and cytochrome content are proportional during growth at low protoheme concentrations, the bacteria incorporate 10 to 20% of the total available protoheme into a membrane-bound respiratory system. This respiratory system includes cytochrome c, a carbon monoxide-binding pigment, and possibly flavoproteins. The pigments can be reversibly reduced by reduced nicotinamide adenine dinucleotide or endogenous metabolism and can be oxidized anaerobically by fumarate or by shaking in air. Electron transport is inhibited by 2-n-nonyl-4-hydroxy-quinoline-N-oxide.

Fatty acid composition of the complex lipids of Staphylococcus aureus during the formation of the membrane-bound electron transport system

In Staphylococcus aureus, 64 fatty acids could be separated by gas-liquid chromatography. The fatty acids consisted of normal, iso, and anteiso saturated fatty acids of from 10 to 21 carbon atoms. Of the total fatty acids, 2 to 4% were normal, iso, and anteiso monoenoic fatty acids. Positional isomers of the normal monoenoic fatty acids could be detected. The fatty acids could be extracted, leaving 1 to 2% of the total fatty acids in the residue. The proportions of the fatty acids in the residue and the total lipids differed significantly. The lipid extract contained less than 0.12% free fatty acid. Between 5 and 10% of the lipid fatty acids were associated with neutral lipids. The majority of the fatty acids were associated with the complex lipids: mono- and diglucosyl diglyceride, phosphatidyl glycerol, lysyl phosphatidyl glycerol, and cardiolipin. The proportions of the fatty acids changed markedly between bacteria grown anaerobically (no membrane-bound electron transport system) and those grown aerobically (containing a functional electron transport system). In each of the complex lipids, the proportions of the fatty acids, as well as the magnitude and direction of change in the molar quantity of the fatty acids per bacterium, changed dramatically between these growth conditions. Since the glucosyl diglycerides and phospholipids were formed from the same pool of diglyceride intermediates, the marked differences in fatty acids indicate that acyl transferase activities must be an important part of complex lipid metabolism in S. aureus.

Membrane lipid changes during formation of a functional electron transport system in Staphylococcus aureus

Addition of oxygen to a culture of anaerobically growing Staphylococcus aureus results in the formation of a membrane-bound, functional electron transport system. With the shift to aerobic growth, there is at least a 15-fold increase in cytochrome a and at least a 55-fold increase in cytochrome oxidase o. At the completion of the shift to aerobic growth, the cytochrome levels equal those found in bacteria grown with aeration throughout the entire growth cycle. Cytochromes b(1) and o are formed first. Their synthesis slows when cytochrome a becomes detectable. Concentrations of cytochromes b(1) and sometimes cytochrome a increase late in the adaptive period. Concomitant with this is a decrease in the oxygen tension at which the rate of oxygen utilization becomes dependent on the oxygen concentration. During the shift to aerobic growth, the protoheme content increases ninefold, and all the protoheme can be accounted for in enzymatically reducible cytochrome b(1) and cytochrome oxidase o. Protoheme, but not a functional cytochrome system, is synthesized by anaerobically growing S. aureus. Heme a appears only after a period of aerobic growth. During the shift to aerobic growth, there is a 1.6-fold increase in the vitamin K(2) content, with an alteration in the ratios of the 35 and 45 carbon side chain isoprenologues. A twofold increase in phosphatidyl glycerol and a 1.6-fold increase in cardiolipin occur with the shift to aerobic growth. Lysyl-phosphtidyl glycerol remains essentially constant in this period. Concentrations of mono- and diglucosyl diglycerides increase coordinately 1.3-fold during the shift to aerobic growth at a 2.5 to 1 m ratio.

Extraction, characterization, and cellular localization of the lipids of Staphylococcus aureus

Satisfactory extraction and assay procedures have been developed for the lipids of Staphylococcus aureus. The following lipids have been characterized in detail: the vitamin K(2), which is shown to exist as isoprenologues with side chains of 35, 40, and 45 carbon atoms; monoglucosyldiglyceride and diglucosyldiglyceride, which account for all the carbohydrate in the lipid extracts; the lysyl ester of phosphatidyl glycerol, phosphatidyl glycerol, and cardiolipin, which account for 98% of the phosphate in the lipid extract. The extraction procedure removes 98% of the total bacterial fatty acids. Acidification of the medium before harvest and refluxing in isopropanol are critical in the extraction procedure for the maximal recovery of lysyl-phosphatidyl glycerol and the glucolipids. The lipids have been shown to be a part of the same membrane as the respiratory pigments.

Indentification and localization of the fatty acids in Haemophilus parainfluenzae

Haemophilus parainfluenzae was capable of synthesizing 22 fatty acids. These fatty acids were equivalent to 4% of the bacterial dry weight. These fatty acids were localized in the membrane-wall complex, which contained the respiratory pigments, the quinone, and the phospholipids. The fatty acids which could be extracted with organic solvents comprised 86% of the total fatty acids of the cell. These fatty acids were distributed as 98% in the phospholipids and 1.9% in the neutral lipids, of which 0.5% were free fatty acids. Palmitic, palmitoleic, oleic, and vaccenic acids comprised 72% of the total fatty acids and were found almost exclusively in the phospholipids. The phospholipids also contained the cyclopropane fatty acids. The neutral lipids contained significant proportions of the odd-numbered branched and straight-chain fatty acids. The principal free fatty acids were n-dodecanoic and pentadecenoic acids. The nonextractable wall complex contained 14% of the total fatty acids. These wall fatty acids were rendered soluble only after saponification. The wall fraction contained all of the beta-hydroxymyristic acid and most of the myristoleic and pentadecenoic acids. The significance of the distribution of fatty acids between nonesterified, neutral lipid, phospholipid, and nonextractible wall remains to be determined.

Effect of glucose on the formation of the membrane-bound electron transport system in Haemophilus parainfluenzae

The catabolism of glucose by Haemophilus parainfluenzae affected the formation of the primary dehydrogenases of the membrane-bound electron transport system. The formation of other components of the respiratory system, 2-demethyl vitamin K(2), cytochrome b(1), cytochrome c(1), and the cytochrome oxidases a(1), a(2), and o, is not affected by the catabolism of glucose. The formation of all components of the electron transport system is controlled by the identity and concentration of the terminal electron acceptors present in the growth medium.

Formation of a functional electron transport system during growth of penicillin-induced spheroplasts of Haemophilus parainfluenzae

Wright, Elizabeth A. (University of Kentucky College of Medicine, Lexington), and David C. White. Formation of a functional electron transport system during growth of penicillin-induced spheroplasts of Haemophilus parainfluenzae. J. Bacteriol. 91:1356-1362. 1966.-Penicillin in a lactose medium can be used to cause the formation of spheroplasts in Haemophilus parainfluenzae. The resulting spheroplasts grew under conditions which produced rapid formation of the electron transport system in the normal bacteria. The following elements that are incorporated into a functionally active electron transport system were formed in spheroplasts: formate and l-lactate dehydrogenases, 2-demethyl vitamin K(2), cytochromes b(1) and c(1), and the cytochrome oxidases. The catabolic enzymes aldolase, glyceraldehyde-3-phosphate dehydrogenase, and malic dehydrogenase showed slight increases in activity. These experiments indicated that spheroplasts can form a fully functional electron transport system essentially similar to that formed during normal growth. The various components of the electron transport system were formed at different rates in the growing spheroplasts.