SYNTHESIS OF 2-DEMETHYL VITAMIN K2 AND THE CYTOCHROME SYSTEM IN HAEMOPHILUS

Influences of growth substrates and oxygen on the electron transport system in Acinetobacter sp. HO1-N

The electron transport system of Acinetobacter sp. HO1-N was studied to determine the specific cytochromes and to measure changes in the composition of the respiratory system due to growth in various concentrations of oxygen or types of growth substrates. Spectrophotometric analysis revealed that the quantity and types of cytochromes changed in response to growth under various concentrations of oxygen. Growth on alkane and nonalkane substrates resulted in only minor differences in cytochrome composition or oxidase activities. Membranes prepared from cells grown under oxygen-limiting conditions contained at least one b-type cytochrome, cytochrome o, cytochrome d, and slight traces of cytochrome a1, whereas membranes prepared from cells grown in the presence of high oxygen concentrations contained only low levels of cytochromes b and o. Polarographic measurements, electron transport inhibitor studies, and photoaction spectrum analyses indicated that cytochromes o, a1, and d were potentially capable of functioning as terminal oxidases in this organism. These experiments also revealed that all three cytochromes may be involved in the oxidation of reduced nicotinamide adenine dinucleotide, succinate, or N,N,N',N'-tetramethyl-p-phenylenediamine.

Changes in cytochrome content and electron transport patterns in Pseudomonas putida as a function of growth phase

Optical absorbance difference spectra of membrane vesicles prepared from aerobically grown Pseudomonas putida indicated that, when harvested in logarithmic phase, the cells contained one c-type cytochrome and two or three b-type cytochromes, one of which was cytochrome o. As the cells grew into stationary phase and the oxygen concentration of the medium dropped to essentially zero, an additional component believed to be cytochrome d was produced. Both the o- and d-type cytochromes might function as terminal oxidases. No a-type cytochromes could be detected at any stage of growth. Polarographic measurement of oxygen utilization revealed that cyanide and azide are effective inhibitors of the oxidation of ascorbate coupled with 2,6-dichlorophenolindophenol or N,N,N',N'-tetramethyl-p-phenylenediamine in respiratory particles from either log-phase or stationary-phase cells. Reduced nicotinamide adenine dinucleotide- or succinate-dependent oxygen utilization, however, was sensitive to these inhibitors only in log-phase particles. These results indicate that an alternate terminal oxidase may be synthesized by this organism in response to restricted oxygen availability and that branching of the respiratory system may result.

Effects of lead on the lipid composition of Micrococcus luteus cells

Micrococcus luteus cells cultivated in medium containing lead salts exhibited a sequence of changes in the quantity of total cellular lipids with essentially no changes from normal cellular yields. The lipid composition of cells cultivated one to four times was moderately decreased (phase I) whereas that of cells cultivated five to six times was reduced by as much as 50% (phase II). Cells cultivated more than six times in lead-containing media had progressively greater quantities of lipid (phase III) approaching that found in control cells. These cells with reestablished lipid contents showed no further effects from more prolonged exposure to lead salts. Chromatographic studies of total lipids of cells of each lipid phase revealed relatively complete lipid compositions. These results indicated that lead is apparently affecting a common biochemical parameter in the biosynthesis of lipids of lipid phase II cells. Changes in the relative quantities of individual components were observed in both the nonpolar and polar lipids in each lipid phase. The most notable changes were the decrease in aliphatic hydrocarbons with concomitant increases in the diglycerides and components identified as a complex family of ketones. Microscopy examinations of control and lead-treated cells revealed electron dense inclusion bodies in membrane fragments in only lead-treated cells.

Inhibition of vitamin K2 and carotenoid synthesis in Staphylococcus aureus by diphenylamine

Diphenylamine at concentrations which did not effect the growth rate inhibited the synthesis of vitamin K(2) in both anaerobic and aerobic cultures by about 50%. At this concentration, diphenylamine inhibited the synthesis of the cyclic carotenoids delta-carotene and the rubixanthins 25 to 35% anaerobically and 60 to 90% aerobically. The inhibition of synthesis of cyclic carotenoids and vitamin K(2) by diphenylamine had no detectable effect on the formation of the membrane-bound electron transport system.

Respiration and protein synthesis in Escherichia coli membrane-envelope fragments. 3. Electron microscopy and analysis of the cytochromes

The membranous nature of pellets obtained from broken Escherichia coli spheroplasts by successive centrifugation at 3500 g (P(1)), 20,000 g (P(2)), and 105,000 g (P(3)), has been established by electron microscopy. Spectrophotometric analysis has shown that about 90% of the cytochromes are concentrated in the particulate fractions. The crude ribosomal pellet (P(3)) contained as much of the total cytochromes as did the pellet obtained at 20,000 g (P(2)). The high cytochrome content of P(3) is consistent with its high oxidative activity (1) and the presence of membrane vesicles in this fraction. Analysis at 77 degrees K intensified the optical extinction of all the cytochrome absorption bands, but the degree of intensification was not uniform for each fraction nor for each band within a given fraction. Carbon monoxide had little or no inhibiting effect on NADH oxidation. Reduced plus carbon monoxide difference spectra yielded artifactual absorption bands in the wave length regions where reduced vs. oxidized absorption bands normally occur. Succinate and NADH, either together or separately, reduced nearly all of the cytochromes, indicating that the cytochrome portion of the electron-transport chain is shared by both substrates. A tentative formulation of the electron-transport chain is presented.

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.

Lipids of Bacteroides melaninogenicus

The lipids of Bacteroides melaninogenicus were readily extractable with chloroform-methanol. Three per cent of the fatty acids were not extractable. The neutral lipids contained 4% of the extractable fatty acids, the stench characteristic of these organisms, and 0.5 mumole of vitamin K(2) isoprenologues K(2)-35, K(2)-40, and K(2)-45 per g (dry weight). This is one-fifth to one-tenth of the vitamin K(2) level found in other bacteria. Ninety-six per cent of the extractable fatty acids were associated with the phospholipids (60 mumoles of lipid phosphate/g, dry weight), which consisted of the diacyl lipids phosphatidic acid, phosphatidyl serine, and phosphatidyl ethanolamine (with phosphatidyl glycerol and cardiolipin in one strain). The unusual phosphosphingolipids ceramide phosphorylethanolamine, ceramide phosphorylglycerol, and ceramide phosphorylglycerol phosphate accounted for 50 to 70% of the lipid phosphate. In protoheme-requiring strains, the protoheme concentration in the growth medium regulated the growth rate and the amount of enzymatically reducible cytochrome c. There were no gross changes in the lipid composition in cells containing different levels of enzymatically reducible cytochrome c.

Phospholipid metabolism during changes in the proportions of membrane-bound respiratory pigments in Haemophilus parainfluenzae

After a transition from high to low oxygen tension, there was a twofold to 50-fold increase in the content of membrane-bound respiratory pigments of Haemophilus parainfluenzae, and there were concurrent changes in the metabolism of the membrane phospholipids: (i) a twofold decrease in the rate of turnover of the phosphate in all the phospholipids; (ii) a shift from simple one-phase, linear incorporation of phosphate into phospholipids to a complex biphasic incorporation of phosphate into phospholipids; and (iii) an increase in the total phospholipids with a slight increase in the proportion of phosphatidylglycerol (PG) and a slight decrease in the proportion of phosphatidylethanolamine (PE). Changes in the rates of incorporation of phosphate into the phospholipids occurred without a change in the rate of bacterial growth. When the compensatory adjustment of the proportions of the respiratory pigments reached a steady state, the total phospholipid, the rate of incorporation of phosphate into phospholipids, and the proportion of PG fell. At steady-state proportions of cytochromes, the proportion of PE and the rate of turnover of the phosphate in the phospholipids increased. All through an incorporation experiment of 1.5 divisions, the specific activity of the phosphate of PG was twice that of phosphatidic acid (PA). The phosphate of PG turned over 1.2 to 1.5 times more rapidly than the phosphate of PA in cells with high and low cytochrome levels. If the PA was an accurate measure of the precursor for the cytidine-5'-diphosphate-diglyceride, which in turn was the precursor of all the lipids, then the results of these experiments suggested that exchange reactions, in addition to synthesis from PA, were involved in phospholipid metabolism. These reactions were more sensitive to changes in oxygen concentration than was the growth rate.

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.

Respiratory pigments of Crithidia fasciculata

Mitochondria were isolated from the heme-requiring insect trypanosomatid, Crithidia fasciculata, which had respiratory activity, showed a P/O ratio with succinate of 0.5 to 1.0, and contained 40 to 50% of the heme a and heme c found in the intact cells. Cytochromes b, c(555), possibly c(1), cytochrome oxidase, a carbon monoxide-binding pigment, and flavoproteins were detectable in the spectra of both intact cells and mitochondria. Cytochrome c(555) is a basic protein that was extracted from cells and mitochondria with salt solutions. The molar ratio of heme c to heme a was approximately 2:1 in both cells and mitochondria. This organism could possibly serve as a model for studies of the respiratory activity of the pathogenic trypanosomes.

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.

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.