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Challenges and Adaptations of Life in Alkaline Habitats. ADVANCES IN BIOCHEMICAL ENGINEERING/BIOTECHNOLOGY 2019; 172:85-133. [DOI: 10.1007/10_2019_97] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
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Detkova EN, Pusheva MA. Energy metabolism in halophilic and alkaliphilic acetogenic bacteria. Microbiology (Reading) 2006. [DOI: 10.1134/s0026261706010012] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
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Krulwich TA, Ito M, Gilmour R, Sturr MG, Guffanti AA, Hicks DB. Energetic problems of extremely alkaliphilic aerobes. BIOCHIMICA ET BIOPHYSICA ACTA 1996; 1275:21-6. [PMID: 8688448 DOI: 10.1016/0005-2728(96)00044-8] [Citation(s) in RCA: 47] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Over a decade of work on extremely alkaliphilic Bacillus species has clarified the extraordinary capacity that these bacteria have for regulating their cytoplasmic pH during growth at pH values well over 10. However, a variety of interesting energetic problems related to their Na(+)-dependent pH homeostatic mechanism are yet to be solved. They include: (1) the clarification of how cell surface layers play a role in a category of alkaliphiles for which this is the case; (2) identification of the putative, electrogenic Na+/H+ antiporter(s) that, in at least some alkaliphiles, may completely account for a cytoplasmic pH that is over 2 pH units lower than the external pH; (3) the determination of whether specific modules or accessory proteins are essential for the efficacy of such antiporters; (4) the mechanistic basis for the increase in the transmembrane electrical potential at the high external pH values at which the potential-consuming antiporter(s) must be most active; and (5) an explanation for the Na(+)-specificity of pH homeostasis in the extremely alkaliphilic bacilli as opposed to the almost equivalent efficacy of K+ for pH homeostasis in at least some non-alkaliphilic aerobes. The current status of such studies and future strategies will be outlined for this central area of alkaliphile energetics. Also considered, will be strategies to elucidate the basis for robust H(+)-coupled oxidative phosphorylation by alkaliphiles at pH values over 10. The maintenance of a cytoplasmic pH over 2 units below the high external pH results in a low bulk electrochemical proton gradient (delta p). To bypass this low delta p, Na(+)-coupling is used for solute uptake even by alkaliphiles that are mesophiles from environments that are not especially Na(+)-rich. This indicates that these bacteria indeed experience a low delta p, to which such coupling is an adaptation. Possible reasons and mechanisms for using a H(+)-coupled rather than a Na(+)-coupled ATP synthase under such circumstances will be discussed.
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Affiliation(s)
- T A Krulwich
- Department of Biochemistry, Mount Sinai School of Medicine of the City University of New York, NY 10029, USA.
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4
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Isolation and characterization of a novel facultatively alkaliphilic bacterium, Corynebacterium sp., grown on n-alkanes. Arch Microbiol 1994. [DOI: 10.1007/bf00282101] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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Padan E, Schuldiner S. Molecular physiology of Na+/H+ antiporters, key transporters in circulation of Na+ and H+ in cells. BIOCHIMICA ET BIOPHYSICA ACTA 1994; 1185:129-51. [PMID: 8167133 DOI: 10.1016/0005-2728(94)90204-6] [Citation(s) in RCA: 121] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Affiliation(s)
- E Padan
- Department of Microbial and Molecular Ecology, Hebrew University of Jerusalem, Israel
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Padan E, Schuldiner S. Na+/H+ antiporters, molecular devices that couple the Na+ and H+ circulation in cells. J Bioenerg Biomembr 1993; 25:647-69. [PMID: 8144493 DOI: 10.1007/bf00770252] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Na+/H+ antiporters are universal devices involved in the Na+ and H+ circulation of both eukaryotes and prokaryotes, thus playing an essential role in the pH and Na+ homeostasis of cells. This review focuses on the major impact of the application of molecular biology tools in the study of the antiporters. These tools permit the verification of the role of the antiporters and provide insights into their unique biology. A novel signal transduction to Na+ involving nhaR, a positive regulator, controls the expression of nhaA in E. coli. A "pH sensor" regulates the activity of Na+/H+ antiporters, both in eukaryotes and prokaryotes. A most intricate signal transduction to pH involving phosphorylation steps controls the activity of nhel in higher mammals. The identification of Histidine 226 in the "pH sensor" of NhaA is a step forward towards the understanding of the pH regulation of these proteins.
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Affiliation(s)
- E Padan
- Division of Microbial and Molecular Ecology, Hebrew University of Jerusalem, Israel
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Abstract
Bacteria respond to changes in internal and external pH by adjusting the activity and synthesis of proteins associated with many different processes, including proton translocation, amino acid degradation, adaptation to acidic or basic conditions and virulence. While, for many of these examples, the physiological and biological consequence of the pH-induced response is clear, the mechanism by which the transcription/translation machinery is signalled is not. These examples are discussed along with several others in which the function of the gene or protein remains a mystery.
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Affiliation(s)
- E R Olson
- Department of Biotechnology, Parke-Davis Pharmaceutical Research Division, Warner-Lambert Company, Ann Arbor, Michigan 48105
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Speelmans G, Poolman B, Konings WN. Amino acid transport in the thermophilic anaerobe Clostridium fervidus is driven by an electrochemical sodium gradient. J Bacteriol 1993; 175:2060-6. [PMID: 8096211 PMCID: PMC204302 DOI: 10.1128/jb.175.7.2060-2066.1993] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
Amino acid transport was studied in membranes of the peptidolytic, thermophilic, anaerobic bacterium Clostridium fervidus. Uptake of the negatively charged amino acid L-glutamate, the neutral amino acid L-serine, and the positively charged amino acid L-arginine was examined in membrane vesicles fused with cytochrome c-containing liposomes. Artificial ion diffusion gradients were also applied to establish the specific driving forces for the individual amino acid transport systems. Each amino acid was driven by the delta psi and delta mu Na+/F and not by the Z delta pH. The Na+ stoichiometry was estimated from the amino acid-dependent 22Na+ efflux and Na(+)-dependent 3H-amino acid efflux. Serine and arginine were symported with 1 Na+ and glutamate with 2 Na+. C. fervidus membranes contain Na+/Na+ exchange activity, but Na+/H+ exchange activity could not be demonstrated.
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Affiliation(s)
- G Speelmans
- Department of Microbiology, University of Groningen, Haren, The Netherlands
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Affiliation(s)
- M H Shirvan
- Teva Pharmaceutical Industries, Jerusalem, Israel
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Krulwich TA, Guffanti AA. Proton-coupled bioenergetic processes in extremely alkaliphilic bacteria. J Bioenerg Biomembr 1992; 24:587-99. [PMID: 1334072 DOI: 10.1007/bf00762351] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Oxidative phosphorylation, which involves an exclusively proton-coupled ATP synthase, and pH homeostasis, which depends upon electrogenic antiport of cytoplasmic Na+ in exchange for H+, are the two known bioenergetic processes that require inward proton translocation in extremely alkaliphilic bacteria. Energy coupling to oxidative phosphorylation is particularly difficult to fit to a strictly chemiosmotic model because of the low bulk electrochemical proton gradient that follows from the maintenance of a cytoplasmic pH just above 8 during growth at pH 10.5 and higher. A large quantitative and variable discrepancy between the putative chemiosmotic driving force and the phosphorylation potential results. This is compounded by a nonequivalence between respiration-dependent bulk gradients and artificially imposed ones in energizing ATP synthesis, and by an apparent requirement for specific respiratory chain complexes that do not relate solely to their role in generation of bulk gradients. Special features of the synthase may contribute to the mode of energization, just as novel features of the Na+ cycle may relate to the extraordinary capacity of the extreme alkaliphiles to achieve pH homeostasis during growth at, or sudden shifts to, an external pH of 10.5 and above.
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Affiliation(s)
- T A Krulwich
- Department of Biochemistry, Mount Sinai School of Medicine, City University of New York, New York 10029
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Ivey D, Guffanti A, Bossewitch J, Padan E, Krulwich T. Molecular cloning and sequencing of a gene from alkaliphilic Bacillus firmus OF4 that functionally complements an Escherichia coli strain carrying a deletion in the nhaA Na+/H+ antiporter gene. J Biol Chem 1991. [DOI: 10.1016/s0021-9258(18)54523-3] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
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Avetisyan AV, Dibrov PA, Semeykina AL, Skulachev VP, Sokolov MV. Adaptation of Bacillus FTU and Escherichia coli to alkaline conditions: the Na+-motive respiration. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 1991. [DOI: 10.1016/0005-2728(91)90013-e] [Citation(s) in RCA: 27] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Hoffmann A, Dimroth P. The electrochemical proton potential of Bacillus alcalophilus. EUROPEAN JOURNAL OF BIOCHEMISTRY 1991; 201:467-73. [PMID: 1657600 DOI: 10.1111/j.1432-1033.1991.tb16304.x] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Bacillus alcalophilus strain ATCC 27647 showed usual growth characteristics, when inoculated at pH 10.4. The cells entered the logarithmic phase at pH 10.3, and as growth continued, the pH dropped further to a value of 8.8 in the stationary phase. B. alcalophilus strain DSM 485 showed comparable growth only in the initial phase after the addition to fresh medium. The small initial growth period was succeeded by a long lag phase, where the pH continuously dropped. The cells resumed growth after the pH was about 10.0 and continued to grow accompanied by a further decrease of external pH. The bioenergetic parameters measured in the initial growth phase of the two strains at high pH (10.1-10.3) were nearly the same, i.e. delta pH = +97 to +110 mV, delta psi = -206 to -213 mV and delta microH+ = -109 to -103 mV. The inverted proton gradient of about 1.7-1.9 at high pH decreased, as the external pH dropped during growth. This led to an increase of the proton motive force (delta microH+), although the membrane potential (delta psi) also declined. The ATP/ADP ratio of strain DSM 485 was high (4.5-5.5) at fast growth during the initial and second growth period. The ratio declined to about 1.5 at the end of the lag phase. At the initial growth phase and at the end of the lag phase, the delta microH+ was, however, the same (approximately -106 mV) and considerably lower than in the middle of the second growth period (approximately -140 mV). Fast growth, therefore, correlates with a high ATP/ADP ratio but not necessarily with a high delta microH+. Addition of gramicidin or carbonylcyanide m-chlorophenylhydrazone stopped growth of B. alcalophilus strain DSM 485 at pH 10.3 or 9.5 and gramicidin immediately decreased the internal ATP/ADP ratio from 4.5 to 1.2 at pH 10.3.
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Affiliation(s)
- A Hoffmann
- Mikrobiologisches Institut, Eidgenössischen Technischen Hochschule, Zürich, Switzerland
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Hoffmann A, Dimroth P. The ATPase of Bacillus alcalophilus. Reconstitution of energy-transducing functions. EUROPEAN JOURNAL OF BIOCHEMISTRY 1991; 196:493-7. [PMID: 1826099 DOI: 10.1111/j.1432-1033.1991.tb15841.x] [Citation(s) in RCA: 30] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
The purified ATPase of Bacillus alcalophilus (F1F0) was reconstituted into proteoliposomes by gradual removal of the detergent Triton X-100 with Amberlite XAD-2. The reconstitution was apparently highly asymmetric with nearly 100% of the F1 portion of the ATPase becoming oriented to the outside. Similar to results obtained with the soluble enzyme, the membrane-bound ATPase required Mg2+ and methanol for maximum activity. With Ca2+ or Mg2+ without methanol, 25% and 1%, respectively, of the maximum activity were observed. The ATPase was unable to pump Na+ ions but catalyzed the translocation of protons into the reconstituted proteoliposomes. Optimum proton translocation required the presence of Mg2+, not Ca2+, as divalent metal ion. The proton pump was inhibited by dicyclohexylcarbodiimide, venturicidin and NaN3. On incubation of the reconstituted ATPase with [14C]dicyclohexylcarbodiimide, subunit c of the enzyme complex became specifically labeled. The proteoliposomes catalyzed the Mg2(+)-dependent incorporation of [32P]phosphate into ATP by ATP/[32P]phosphate exchange. This exchange was little affected by monensin, but was completely abolished by the uncoupler carbonyl cyanide m-chlorophenylhydrazone. Protons and not Na+ are thus the coupling ions of the ATPase of B. alcalophilus.
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Affiliation(s)
- A Hoffmann
- Mikrobiologisches Institut, Eidgenössischen Technischen Hochschule, Zürich, Switzerland
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Facultative alkaliphiles lack fatty acid desaturase activity and lose the ability to grow at near-neutral pH when supplemented with an unsaturated fatty acid. J Bacteriol 1991; 173:1331-4. [PMID: 1991725 PMCID: PMC207259 DOI: 10.1128/jb.173.3.1331-1334.1991] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Two obligate alkaliphiles were found to have high levels of fatty acid desaturase, whereas two facultative alkaliphiles had no detectable activity. Supplementation of the growth medium of one facultative strain with palmitoleic acid, but not palmitic acid, at pH 7.5 inhibited growth. The obligate strain outgrows the facultative strain in a chemostat at a very high pH, whereas the converse is true at a pH of 7.5, and the two strains grow equally well at pH 9.0. Thus, the obligate strain is compromised at a near-neutral pH but is better adapted than a related facultative alkaliphile to an extremely alkaline pH.
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Hoffmann A, Dimroth P. The ATPase of Bacillus alcalophilus. Purification and properties of the enzyme. EUROPEAN JOURNAL OF BIOCHEMISTRY 1990; 194:423-30. [PMID: 2148515 DOI: 10.1111/j.1432-1033.1990.tb15635.x] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
The ATPase of Bacillus alcalophilus was extracted from the bacterial membranes with Triton X-100 and purified by hydroxyapatite column chromatography. SDS gel-electrophoresis of the purified protein indicated the typical subunit pattern of an F1F0 structure with five F1 subunits (alpha, beta, gamma, delta, epsilon) and three F0 subunits (a,b,c). The alpha and beta subunits were antigens for an antiserum against the corresponding subunits of the ATPase of Escherichia coli. Subunit c was extracted from the bacterial membranes with chloroform/methanol. Its amino acid composition was in the range of subunits c from other ATPases. Maximal ATPase activity was observed in the presence of 2-5 mM MgCl2, an ATP/Mg2+ ratio of 2:1 and 25% methanol. In the absence of methanol, only about 1% of the maximal activity was observed. The enzyme was also activated by Ca2+ (in the absence of methanol), reaching about 30% of the maximal activity. The dependence of initial velocity versus ATP of the Ca2(+)-activated but not of the Mg2+/methanol-activated enzyme indicted cooperativity with three strongly cooperative binding sites.
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Affiliation(s)
- A Hoffmann
- Mikrobiologisches Institut der Eidgenössischen Technischen Hochschule, Zürich, Switzerland
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Rottenberg H. Decoupling of oxidative phosphorylation and photophosphorylation. BIOCHIMICA ET BIOPHYSICA ACTA 1990; 1018:1-17. [PMID: 1695856 DOI: 10.1016/0005-2728(90)90103-b] [Citation(s) in RCA: 68] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Affiliation(s)
- H Rottenberg
- Pathology Department, Hahnemann University School of Medicine, Philadelphia, PA
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19
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Hoffmann A, Laubinger W, Dimroth P. Na+-coupled ATP synthesis in Propionigenium modestum. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 1990. [DOI: 10.1016/0005-2728(90)90250-8] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Abstract
A Na+/H+ antiporter catalyses coupled Na+ extrusion and H+ uptake across the membranes of extremely alkalophilic bacilli. This exchange is electrogenic, with H+ translocated inward greater than Na+ extruded. It is energized by the delta chi 2 component of the delta mu H+ that is established during primary proton pumping by the alkalophile respiratory chain complexes. These complexes abound in the membranes of extreme alkalophiles. Combined activity of the respiratory chain, the antiporter, and solute transport systems that are coupled to Na+ re-entry, allow the alkalophiles to maintain a cytoplasmic pH that is several pH units more acidic than optimal external pH values for growth. There is no compelling evidence for a specific and necessary role for any ion other than sodium in pH homeostasis, and although there is very high cytoplasmic buffering capacity in the alkaline range, active mechanisms for pH homeostasis are crucial. Energization of the antiporter as well as the proton translocating F1F0-ATPase that catalyses ATP synthesis in the extreme alkalophiles must accommodate the problem of the low net delta mu H+ and the very low concentrations of protons, per se, in the external medium. This problem is by-passed by other bioenergetic work functions, such as solute uptake or motility, that utilize sodium ions for energy-coupling in the place of protons.
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Affiliation(s)
- T A Krulwich
- Department of Biochemistry, Mount Sinai School of Medicine, City University of New York, N.Y
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Atsumi T, Sugiyama S, Cragoe EJ, Imae Y. Specific inhibition of the Na(+)-driven flagellar motors of alkalophilic Bacillus strains by the amiloride analog phenamil. J Bacteriol 1990; 172:1634-9. [PMID: 2155207 PMCID: PMC208642 DOI: 10.1128/jb.172.3.1634-1639.1990] [Citation(s) in RCA: 61] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Amiloride, a specific inhibitor for the Na(+)-driven flagellar motors of alkalophilic Bacillus strains, was found to cause growth inhibition; therefore, the use of amiloride for the isolation of motility mutants was difficult. On the other hand, phenamil, an amiloride analog, inhibited motor rotation without affecting cell growth. A concentration of 50 microM phenamil completely inhibited the motility of strain RA-1 but showed no effect on the membrane potential, the intracellular pH, or Na(+)-coupled amino acid transport, which was consistent with the fact that there was no effect on cell growth. Kinetic analysis of the inhibition of motility by phenamil indicated that the inhibition was noncompetitive with Na+ in the medium. A motility mutant was isolated as a swarmer on a swarm agar plate containing 50 microM phenamil. The motility of the mutant showed an increased resistance to phenamil but normal sensitivity to amiloride. These results suggest that phenamil and amiloride interact at different sites on the motor. By examining various bacterial species, phenamil was found to be a specific and potent inhibitor for the Na(+)-driven flaggellar motors not only in various strains of alkalophilic Bacillus spp. but also in a marine Vibrio sp.
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Affiliation(s)
- T Atsumi
- Department of Molecular Biology, Faculty of Science, Nagoya University, Japan
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Dependence of the proton translocation stoichiometry of cyanobacterial and chloroplast H+-ATP synthase on the membrane composition. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 1990. [DOI: 10.1016/0005-2728(90)90075-f] [Citation(s) in RCA: 28] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Krulwich TA, Guffanti AA. The Na+ cycle of extreme alkalophiles: a secondary Na+/H+ antiporter and Na+/solute symporters. J Bioenerg Biomembr 1989; 21:663-77. [PMID: 2687260 DOI: 10.1007/bf00762685] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Extremely alkalophilic bacteria that grow optimally at pH 10.5 and above are generally aerobic bacilli that grow at mesophilic temperatures and moderate salt levels. The adaptations to alkalophily in these organisms may be distinguished from responses to combined challenges of high pH together with other stresses such as salinity or anaerobiosis. These alkalophiles all possess a simple and physiologically crucial Na+ cycle that accomplishes the key task of pH homeostasis. An electrogenic, secondary Na+/H+ antiporter is energized by the electrochemical proton gradient formed by the proton-pumping respiratory chain. The antiporter facilitates maintenance of a pHin that is two or more pH units lower than pHout at optimal pH values for growth. It also largely converts the initial electrochemical proton gradient formed by respiration into an electrochemical sodium gradient that energizes motility as well as a plethora of Na+ solute symporters. These symporters catalyze solute accumulation and, importantly, reentry of Na+. The extreme nonmarine alkalophiles exhibit no primary sodium pumping dependent upon either respiration or ATP. ATP synthesis is not part of their Na+ cycle. Rather, the specific details of oxidative phosphorylation in these organisms are an interesting analogue of the same process in mitochondria, and may utilize some common features to optimize energy transduction.
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Affiliation(s)
- T A Krulwich
- Department of Biochemistry, Mount Sinai School of Medicine of the City University of New York, New York 10029
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Rohde M, Mayer F, Hicks DB, Krulwich TA. Immunoelectron microscopic localization of the F1F0 ATPase (ATP synthase) on the cytoplasmic membrane of alkalophilic Bacillus firmus RAB. BIOCHIMICA ET BIOPHYSICA ACTA 1989; 985:233-5. [PMID: 2529907 DOI: 10.1016/0005-2736(89)90369-6] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Evidence that the F1F0 ATPase (ATP synthase) of alkalophilic Bacillus firmus RAB is localized exclusively on the cytoplasmic membrane was obtained by immunogold electron microscopy using a highly specific polyclonal antibody against the beta subunit of Escherichia coli F1F0 ATPase. The energetic problem faced by cells of B. firmus RAB growing oxidatively at pH 10.5 despite a low protonmotive force across the cytoplasmic membrane cannot, therefore, be circumvented by localization of energy transducing functions on hypothetical internal membranes.
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Affiliation(s)
- M Rohde
- Gesellschaft für Biotechnologische Forschung, Braunschweig, F.R.G
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Abstract
Novel observations related to the Na+-linked energy transduction in bacterial membranes are considered. It is concluded that besides the well-known systems based on the circulation of protons, there are those based on the circulation of Na+. In some cases, H+ and Na+ cycles co-exist in one and the same membrane. Representatives of the 'sodium world', i.e. cells possessing primary Na+ pumps (delta mu Na generators and consumers) are found in many genera of bacteria. Among the delta mu Na generators, one should mention Na+-NADH-quinone reductase and Na+-terminal oxidase of the respiratory chain, Na+-decarboxylases and Na+-ATPases. For delta mu Na consumers, there are Na+-ATP-synthases, Na+-metabolite symporters and Na+ motors. Sometimes, one and the same enzyme can transport H+ or, alternatively, Na+. For instance, an Na+-ATP-synthase of the F0F1 type translocates H+ when Na+ is absent. Employment of the Na+ cycle, apart from or instead of the H+ cycle, increases the resistance of bacteria to alkaline or protonophore-containing media and, apparently, to some other unfavourable conditions.
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Affiliation(s)
- V P Skulachev
- Department of Bioenergetics, A.N. Belozersky Laboratory of Molecular Biology and Bioorganic Chemistry, Moscow State University, USSR
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Kitada M, Onda K, Horikoshi K. The sodium/proton antiport system in a newly isolated alkalophilic Bacillus sp. J Bacteriol 1989; 171:1879-84. [PMID: 2539355 PMCID: PMC209835 DOI: 10.1128/jb.171.4.1879-1884.1989] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
The pH homeostasis and the sodium/proton antiport system have been studied in the newly isolated alkalophilic Bacillus sp. strain N-6, which could grow on media in a pH range from 7 to 10, and in its nonalkalophilic mutant. After a quick shift in external pH from 8 to 10 by the addition of Na2CO3, the delta pH (inside acid) in the cells of strain N-6 was immediately established, and the pH homeostatic state was maintained for more than 20 min in an alkaline environment. However, under the same conditions, the pH homeostasis was not observed in the cells of nonalkalophilic mutant, and the cytoplasmic pH immediately rose to pH 10. On the other hand, the results of the rapid acidification from pH 9 to 7 showed that the internal pH was maintained as more basic than the external pH in a neutral medium in both strains. The Na+/H+ antiport system has been characterized by either the effect of Na+ on delta pH formation or 22Na+ efflux in Na+-loaded right-side-out membrane vesicles of strain N-6. Na+- or Li+-loaded vesicles exhibited a reversed delta pH (inside acid) after the addition of electron donors (ascorbate plus tetramethyl-p-phenylenediamine) at both pH 7 and 9, whereas choline-loaded vesicles generated delta pHs of the conventional orientation (inside alkaline). 22Na+ was actively extruded from 22Na+-loaded vesicles whose potential was negative at pH 7 and 9. The inclusion of carbonyl cyanide m-chlorophenylhydrazone inhibited 22Na+ efflux in the presence of electron donors. These results indicate that the Na+/H+ antiport system in this strain operates electrogenically over a range of external pHs from 7 to 10 and plays a role in pH homeostasis at the alkaline pH range. The pH homeostasis at neutral ph was studied in more detail. K+ -depleted cells showed no delta pH (acid out) in the neutral conditions in the absence of K+, whereas these cells generated a delta pH if K+ was present in the medium. This increase of internal pH was accompanied by K+ uptake from the medium. These results suggest that electrogenic K+ entry allows extrusion of H+ from cells by the primary proton pump at neutral pH.
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Clejan S, Guffanti AA, Cohen MA, Krulwich TA. Mutation of Bacillus firmus OF4 to duramycin resistance results in substantial replacement of membrane lipid phosphatidylethanolamine by its plasmalogen form. J Bacteriol 1989; 171:1744-6. [PMID: 2921248 PMCID: PMC209809 DOI: 10.1128/jb.171.3.1744-1746.1989] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Mutant strains of alkalophilic Bacillus firmus OF4 that were selected for resistance to duramycin had greatly reduced levels of membrane diacylphosphatidylethanolamine, as had been found in studies of such mutants of Bacillus subtilis. In the B. firmus strains, however, substantial levels of plasmenylethanolamine were found. This is an unusual membrane component for an aerobic eubacterium, but the presence of trace amounts even in the wild type was confirmed in experiments with 32Pi-labeled growth medium. The membrane lipid composition of the duramycin-resistant strains had several other changes that also left alkalophilic growth unimpaired.
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Affiliation(s)
- S Clejan
- Department of Pathology, City Hospital Center at Elmhurst, New York
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