1
|
Huening KA, Groves JT, Wildenthal JA, Tabita FR, North JA. Escherichia coli possessing the dihydroxyacetone phosphate shunt utilize 5'-deoxynucleosides for growth. Microbiol Spectr 2024; 12:e0308623. [PMID: 38441472 PMCID: PMC10986504 DOI: 10.1128/spectrum.03086-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2023] [Accepted: 02/17/2024] [Indexed: 03/08/2024] Open
Abstract
All organisms utilize S-adenosyl-l-methionine (SAM) as a key co-substrate for the methylation of biological molecules, the synthesis of polyamines, and radical SAM reactions. When these processes occur, 5'-deoxy-nucleosides are formed as byproducts such as S-adenosyl-l-homocysteine, 5'-methylthioadenosine (MTA), and 5'-deoxyadenosine (5dAdo). A prevalent pathway found in bacteria for the metabolism of MTA and 5dAdo is the dihydroxyacetone phosphate (DHAP) shunt, which converts these compounds into dihydroxyacetone phosphate and 2-methylthioacetaldehyde or acetaldehyde, respectively. Previous work in other organisms has shown that the DHAP shunt can enable methionine synthesis from MTA or serve as an MTA and 5dAdo detoxification pathway. Rather, the DHAP shunt in Escherichia coli ATCC 25922, when introduced into E. coli K-12, enables the use of 5dAdo and MTA as a carbon source for growth. When MTA is the substrate, the sulfur component is not significantly recycled back to methionine but rather accumulates as 2-methylthioethanol, which is slowly oxidized non-enzymatically under aerobic conditions. The DHAP shunt in ATCC 25922 is active under oxic and anoxic conditions. Growth using 5-deoxy-d-ribose was observed during aerobic respiration and anaerobic respiration with Trimethylamine N-oxide (TMAO), but not during fermentation or respiration with nitrate. This suggests the DHAP shunt may only be relevant for extraintestinal pathogenic E. coli lineages with the DHAP shunt that inhabit oxic or TMAO-rich extraintestinal environments. This reveals a heretofore overlooked role of the DHAP shunt in carbon and energy metabolism from ubiquitous SAM utilization byproducts and suggests a similar role may occur in other pathogenic and non-pathogenic bacteria with the DHAP shunt. IMPORTANCE The acquisition and utilization of organic compounds that serve as growth substrates are essential for Escherichia coli to grow and multiply. Ubiquitous enzymatic reactions involving S-adenosyl-l-methionine as a co-substrate by all organisms result in the formation of the 5'-deoxy-nucleoside byproducts, 5'-methylthioadenosine and 5'-deoxyadenosine. All E. coli possess a conserved nucleosidase that cleaves these 5'-deoxy-nucleosides into 5-deoxy-pentose sugars for adenine salvage. The DHAP shunt pathway is found in some extraintestinal pathogenic E. coli, but its function in E. coli possessing it has remained unknown. This study reveals that the DHAP shunt enables the utilization of 5'-deoxy-nucleosides and 5-deoxy-pentose sugars as growth substrates in E. coli strains with the pathway during aerobic respiration and anaerobic respiration with TMAO, but not fermentative growth. This provides an insight into the diversity of sugar compounds accessible by E. coli with the DHAP shunt and suggests that the DHAP shunt is primarily relevant in oxic or TMAO-rich extraintestinal environments.
Collapse
Affiliation(s)
| | - Joshua T. Groves
- Department of Microbiology, The Ohio State University, Columbus, Ohio, USA
| | - John A. Wildenthal
- Department of Microbiology, The Ohio State University, Columbus, Ohio, USA
| | - F. Robert Tabita
- Department of Microbiology, The Ohio State University, Columbus, Ohio, USA
| | - Justin A. North
- Department of Microbiology, The Ohio State University, Columbus, Ohio, USA
| |
Collapse
|
2
|
Huening KA, Groves JT, Wildenthal JA, Tabita FR, North JA. Utilization of 5'-deoxy-nucleosides as Growth Substrates by Extraintestinal Pathogenic E. coli via the Dihydroxyacetone Phosphate Shunt. bioRxiv 2023:2023.08.10.552779. [PMID: 37609188 PMCID: PMC10441430 DOI: 10.1101/2023.08.10.552779] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/24/2023]
Abstract
All organisms utilize S-adenosyl-l-methionine (SAM) as a key co-substrate for methylation of biological molecules, synthesis of polyamines, and radical SAM reactions. When these processes occur, 5'-deoxy-nucleosides are formed as byproducts such as S-adenosyl-l-homocysteine (SAH), 5'-methylthioadenosine (MTA), and 5'-deoxyadenosine (5dAdo). One of the most prevalent pathways found in bacteria for the metabolism of MTA and 5dAdo is the DHAP shunt, which converts these compounds into dihydroxyacetone phosphate (DHAP) and 2-methylthioacetaldehyde or acetaldehyde, respectively. Previous work has shown that the DHAP shunt can enable methionine synthesis from MTA or serve as an MTA and 5dAdo detoxification pathway. Here we show that in Extraintestinal Pathogenic E. coil (ExPEC), the DHAP shunt serves none of these roles in any significant capacity, but rather physiologically functions as an assimilation pathway for use of MTA and 5dAdo as growth substrates. This is further supported by the observation that when MTA is the substrate for the ExPEC DHAP shunt, the sulfur components is not significantly recycled back to methionine, but rather accumulates as 2-methylthioethanol, which is slowly oxidized non-enzymatically under aerobic conditions. While the pathway is active both aerobically and anaerobically, it only supports aerobic ExPEC growth, suggesting that it primarily functions in oxygenic extraintestinal environments like blood and urine versus the predominantly anoxic gut. This reveals a heretofore overlooked role of the DHAP shunt in carbon assimilation and energy metabolism from ubiquitous SAM utilization byproducts and suggests a similar role may occur in other pathogenic and non-pathogenic bacteria with the DHAP shunt.
Collapse
Affiliation(s)
| | - Joshua T. Groves
- The Ohio State University Department of Microbiology, Columbus, OH, 43210
| | - John A. Wildenthal
- The Ohio State University Department of Microbiology, Columbus, OH, 43210
| | - F. Robert Tabita
- The Ohio State University Department of Microbiology, Columbus, OH, 43210
| | - Justin A. North
- The Ohio State University Department of Microbiology, Columbus, OH, 43210
| |
Collapse
|
3
|
North JA, Narrowe AB, Xiong W, Byerly KM, Zhao G, Young SJ, Murali S, Wildenthal JA, Cannon WR, Wrighton KC, Hettich RL, Tabita FR. A nitrogenase-like enzyme system catalyzes methionine, ethylene, and methane biogenesis. Science 2020; 369:1094-1098. [PMID: 32855335 DOI: 10.1126/science.abb6310] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2020] [Accepted: 06/12/2020] [Indexed: 12/16/2022]
Abstract
Bacterial production of gaseous hydrocarbons such as ethylene and methane affects soil environments and atmospheric climate. We demonstrate that biogenic methane and ethylene from terrestrial and freshwater bacteria are directly produced by a previously unknown methionine biosynthesis pathway. This pathway, present in numerous species, uses a nitrogenase-like reductase that is distinct from known nitrogenases and nitrogenase-like reductases and specifically functions in C-S bond breakage to reduce ubiquitous and appreciable volatile organic sulfur compounds such as dimethyl sulfide and (2-methylthio)ethanol. Liberated methanethiol serves as the immediate precursor to methionine, while ethylene or methane is released into the environment. Anaerobic ethylene production by this pathway apparently explains the long-standing observation of ethylene accumulation in oxygen-depleted soils. Methane production reveals an additional bacterial pathway distinct from archaeal methanogenesis.
Collapse
Affiliation(s)
- Justin A North
- Department of Microbiology, The Ohio State University, Columbus, OH 43210, USA
| | - Adrienne B Narrowe
- Department of Soil and Crop Sciences, Colorado State University, Fort Collins, CO 80523, USA
| | - Weili Xiong
- Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN 37830, USA
| | - Kathryn M Byerly
- Department of Microbiology, The Ohio State University, Columbus, OH 43210, USA
| | - Guanqi Zhao
- Department of Microbiology, The Ohio State University, Columbus, OH 43210, USA
| | - Sarah J Young
- Department of Microbiology, The Ohio State University, Columbus, OH 43210, USA
| | - Srividya Murali
- Department of Microbiology, The Ohio State University, Columbus, OH 43210, USA
| | - John A Wildenthal
- Department of Microbiology, The Ohio State University, Columbus, OH 43210, USA
| | - William R Cannon
- Pacific Northwest National Laboratory, Richland, WA 99352, USA.,Department of Mathematics, University of California, Riverside, Riverside, CA 92507, USA
| | - Kelly C Wrighton
- Department of Soil and Crop Sciences, Colorado State University, Fort Collins, CO 80523, USA
| | - Robert L Hettich
- Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN 37830, USA
| | - F Robert Tabita
- Department of Microbiology, The Ohio State University, Columbus, OH 43210, USA.
| |
Collapse
|
4
|
Satagopan S, North JA, Arbing MA, Varaljay VA, Haines SN, Wildenthal JA, Byerly KM, Shin A, Tabita FR. Structural Perturbations of Rhodopseudomonas palustris Form II RuBisCO Mutant Enzymes That Affect CO2 Fixation. Biochemistry 2019; 58:3880-3892. [DOI: 10.1021/acs.biochem.9b00617] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Affiliation(s)
- Sriram Satagopan
- Department of Microbiology, The Ohio State University, Columbus, Ohio 43210, United States
| | - Justin A. North
- Department of Microbiology, The Ohio State University, Columbus, Ohio 43210, United States
| | - Mark A. Arbing
- UCLA-DOE Institute, University of California, Los Angeles, Los Angeles, California 90095, United States
| | - Vanessa A. Varaljay
- Department of Microbiology, The Ohio State University, Columbus, Ohio 43210, United States
| | - Sidney N. Haines
- Department of Microbiology, The Ohio State University, Columbus, Ohio 43210, United States
| | - John A. Wildenthal
- Department of Microbiology, The Ohio State University, Columbus, Ohio 43210, United States
| | - Kathryn M. Byerly
- Department of Microbiology, The Ohio State University, Columbus, Ohio 43210, United States
| | - Annie Shin
- UCLA-DOE Institute, University of California, Los Angeles, Los Angeles, California 90095, United States
| | - F. Robert Tabita
- Department of Microbiology, The Ohio State University, Columbus, Ohio 43210, United States
| |
Collapse
|
5
|
Thomas PJ, Boller AJ, Satagopan S, Tabita FR, Cavanaugh CM, Scott KM. Isotope discrimination by form IC RubisCO from
Ralstonia eutropha
and
Rhodobacter sphaeroides
, metabolically versatile members of ‘
Proteobacteria
’ from aquatic and soil habitats. Environ Microbiol 2018; 21:72-80. [DOI: 10.1111/1462-2920.14423] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2015] [Accepted: 09/18/2018] [Indexed: 11/29/2022]
Affiliation(s)
- Phaedra J. Thomas
- Department of Integrative Biology University of South Florida Tampa FL USA
| | - Amanda J. Boller
- Department of Integrative Biology University of South Florida Tampa FL USA
| | - Sriram Satagopan
- Department of Microbiology The Ohio State University Columbus OH USA
| | - F. Robert Tabita
- Department of Microbiology The Ohio State University Columbus OH USA
| | - Colleen M. Cavanaugh
- Department of Organismic and Evolutionary Biology Harvard University Cambridge MA USA
| | - Kathleen M. Scott
- Department of Integrative Biology University of South Florida Tampa FL USA
| |
Collapse
|
6
|
North JA, Miller AR, Wildenthal JA, Young SJ, Tabita FR. Microbial pathway for anaerobic 5'-methylthioadenosine metabolism coupled to ethylene formation. Proc Natl Acad Sci U S A 2017; 114:E10455-E10464. [PMID: 29133429 PMCID: PMC5715764 DOI: 10.1073/pnas.1711625114] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Numerous cellular processes involving S-adenosyl-l-methionine result in the formation of the toxic by-product, 5'-methylthioadenosine (MTA). To prevent inhibitory MTA accumulation and retain biologically available sulfur, most organisms possess the "universal" methionine salvage pathway (MSP). However, the universal MSP is inherently aerobic due to a requirement of molecular oxygen for one of the key enzymes. Here, we report the presence of an exclusively anaerobic MSP that couples MTA metabolism to ethylene formation in the phototrophic bacteria Rhodospirillum rubrum and Rhodopseudomonas palustris In vivo metabolite analysis of gene deletion strains demonstrated that this anaerobic MSP functions via sequential action of MTA phosphorylase (MtnP), 5-(methylthio)ribose-1-phosphate isomerase (MtnA), and an annotated class II aldolase-like protein (Ald2) to form 2-(methylthio)acetaldehyde as an intermediate. 2-(Methylthio)acetaldehyde is reduced to 2-(methylthio)ethanol, which is further metabolized as a usable organic sulfur source, generating stoichiometric amounts of ethylene in the process. Ethylene induction experiments using 2-(methylthio)ethanol versus sulfate as sulfur sources further indicate anaerobic ethylene production from 2-(methylthio)ethanol requires protein synthesis and that this process is regulated. Finally, phylogenetic analysis reveals that the genes corresponding to these enzymes, and presumably the pathway, are widespread among anaerobic and facultatively anaerobic bacteria from soil and freshwater environments. These results not only establish the existence of a functional, exclusively anaerobic MSP, but they also suggest a possible route by which ethylene is produced by microbes in anoxic environments.
Collapse
Affiliation(s)
- Justin A North
- Department of Microbiology, The Ohio State University, Columbus, OH 43210
| | - Anthony R Miller
- Department of Microbiology, The Ohio State University, Columbus, OH 43210
| | - John A Wildenthal
- Department of Microbiology, The Ohio State University, Columbus, OH 43210
| | - Sarah J Young
- Department of Microbiology, The Ohio State University, Columbus, OH 43210
| | - F Robert Tabita
- Department of Microbiology, The Ohio State University, Columbus, OH 43210
| |
Collapse
|
7
|
Buchanan BB, Sirevåg R, Fuchs G, Ivanovsky RN, Igarashi Y, Ishii M, Tabita FR, Berg IA. The Arnon-Buchanan cycle: a retrospective, 1966-2016. Photosynth Res 2017; 134:117-131. [PMID: 29019085 DOI: 10.1007/s11120-017-0429-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/08/2017] [Accepted: 08/03/2017] [Indexed: 06/07/2023]
Abstract
For the first decade following its description in 1954, the Calvin-Benson cycle was considered the sole pathway of autotrophic CO2 assimilation. In the early 1960s, experiments with fermentative bacteria uncovered reactions that challenged this concept. Ferredoxin was found to donate electrons directly for the reductive fixation of CO2 into alpha-keto acids via reactions considered irreversible. Thus, pyruvate and alpha-ketoglutarate could be synthesized from CO2, reduced ferredoxin and acetyl-CoA or succinyl-CoA, respectively. This work opened the door to the discovery that reduced ferredoxin could drive the Krebs citric acid cycle in reverse, converting the pathway from its historical role in carbohydrate breakdown to one fixing CO2. Originally uncovered in photosynthetic green sulfur bacteria, the Arnon-Buchanan cycle has since been divorced from light and shown to function in a variety of anaerobic chemoautotrophs. In this retrospective, colleagues who worked on the cycle at its inception in 1966 and those presently working in the field trace its development from a controversial reception to its present-day inclusion in textbooks. This pathway is now well established in major groups of chemoautotrophic bacteria, instead of the Calvin-Benson cycle, and is increasingly referred to as the Arnon-Buchanan cycle. In this retrospective, separate sections have been written by the authors indicated. Bob Buchanan wrote the abstract and the concluding comments.
Collapse
Affiliation(s)
- Bob B Buchanan
- Department of Plant & Microbial Biology, University of California, 111 Koshland Hall, Berkeley, CA, 94720, USA.
| | - Reidun Sirevåg
- Department of Biosciences, University of Oslo, Blindern, Box 1066, 0316, Oslo, Norway
| | - Georg Fuchs
- Mikrobiologie, Fakultät für Biologie, Albert-Ludwigs-Universität Freiburg, Schänzlestrasse 1, 79104, Freiburg, Germany
| | - Ruslan N Ivanovsky
- Department of Microbiology, M.V. Lomonosov Moscow State University, 1/12 Lenin's Hills, Moscow, Russia, 119991
| | - Yasuo Igarashi
- Southwest University, Chongqing, 2 Tiansheng Rd, Beibei Qu, Chongqing Shi, 400700, China
| | - Masaharu Ishii
- Department of Biotechnology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Yayoi 1-1-1, Bunkyo-ku, Tokyo, 113-8657, Japan
| | - F Robert Tabita
- Department of Microbiology, The Ohio State University, 484 West 12th Avenue, Columbus, OH, 43210, USA
| | - Ivan A Berg
- Institute for Molecular Microbiology and Biotechnology, University of Münster, Corrensstr. 3, 48149, Münster, Germany
| |
Collapse
|
8
|
Satagopan S, Sun Y, Parquette JR, Tabita FR. Synthetic CO 2-fixation enzyme cascades immobilized on self-assembled nanostructures that enhance CO 2/O 2 selectivity of RubisCO. Biotechnol Biofuels 2017; 10:175. [PMID: 28694846 PMCID: PMC5501267 DOI: 10.1186/s13068-017-0861-6] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/26/2017] [Accepted: 06/27/2017] [Indexed: 06/07/2023]
Abstract
BACKGROUND With increasing concerns over global warming and depletion of fossil-fuel reserves, it is attractive to develop innovative strategies to assimilate CO2, a greenhouse gas, into usable organic carbon. Cell-free systems can be designed to operate as catalytic platforms with enzymes that offer exceptional selectivity and efficiency, without the need to support ancillary reactions of metabolic pathways operating in intact cells. Such systems are yet to be exploited for applications involving CO2 utilization and subsequent conversion to valuable products, including biofuels. The Calvin-Benson-Bassham (CBB) cycle and the enzyme ribulose 1,5-bisphosphate carboxylase/oxygenase (RubisCO) play a pivotal role in global CO2 fixation. RESULTS We hereby demonstrate the co-assembly of two RubisCO-associated multienzyme cascades with self-assembled synthetic amphiphilic peptide nanostructures. The immobilized enzyme cascades sequentially convert either ribose-5-phosphate (R-5-P) or glucose, a simpler substrate, to ribulose 1,5-bisphosphate (RuBP), the acceptor for incoming CO2 in the carboxylation reaction catalyzed by RubisCO. Protection from proteolytic degradation was observed in nanostructures associated with the small dimeric form of RubisCO and ancillary enzymes. Furthermore, nanostructures associated with a larger variant of RubisCO resulted in a significant enhancement of the enzyme's selectivity towards CO2, without adversely affecting the catalytic activity. CONCLUSIONS The ability to assemble a cascade of enzymes for CO2 capture using self-assembling nanostructure scaffolds with functional enhancements show promise for potentially engineering entire pathways (with RubisCO or other CO2-fixing enzymes) to redirect carbon from industrial effluents into useful bioproducts.
Collapse
Affiliation(s)
- Sriram Satagopan
- Department of Microbiology, The Ohio State University, 484 West 12th Avenue, Columbus, OH 43210-1292 USA
| | - Yuan Sun
- Department of Chemistry and Biochemistry, The Ohio State University, 100 West 18th Avenue, Columbus, OH 43210-1185 USA
| | - Jon R. Parquette
- Department of Chemistry and Biochemistry, The Ohio State University, 100 West 18th Avenue, Columbus, OH 43210-1185 USA
| | - F. Robert Tabita
- Department of Microbiology, The Ohio State University, 484 West 12th Avenue, Columbus, OH 43210-1292 USA
| |
Collapse
|
9
|
Satagopan S, Tabita FR. RubisCO selection using the vigorously aerobic and metabolically versatile bacterium Ralstonia eutropha. FEBS J 2016; 283:2869-80. [PMID: 27261087 DOI: 10.1111/febs.13774] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2016] [Revised: 05/06/2016] [Accepted: 06/03/2016] [Indexed: 11/29/2022]
Abstract
UNLABELLED Recapturing atmospheric CO2 is key to reducing global warming and increasing biological carbon availability. Ralstonia eutropha is a biotechnologically useful aerobic bacterium that uses the Calvin-Benson-Bassham (CBB) cycle and the enzyme ribulose 1,5-bisphosphate carboxylase/oxygenase (RubisCO) for CO2 utilization, suggesting that it may be a useful host to bioselect RubisCO molecules with improved CO2 -capture capabilities. A host strain of R. eutropha was constructed for this purpose after deleting endogenous genes encoding two related RubisCOs. This strain could be complemented for CO2 -dependent growth by introducing native or heterologous RubisCO genes. Mutagenesis and suppressor selection identified amino acid substitutions in a hydrophobic region that specifically influences RubisCO's interaction with its substrates, particularly O2 , which competes with CO2 at the active site. Unlike most RubisCOs, the R. eutropha enzyme has evolved to retain optimal CO2 -fixation rates in a fast-growing host, despite the presence of high levels of competing O2 . Yet its structure-function properties resemble those of several commonly found RubisCOs, including the higher plant enzymes, allowing strategies to engineer analogous enzymes. Because R. eutropha can be cultured rapidly under harsh environmental conditions (e.g., with toxic industrial flue gas), in the presence of near saturation levels of oxygen, artificial selection and directed evolution studies in this organism could potentially impact efforts toward improving RubisCO-dependent biological CO2 utilization in aerobic environments. ENZYMES d-ribulose 1,5-bisphosphate carboxylase/oxygenase, EC 4.1.1.39; phosphoribulokinase, EC 2.7.1.19.
Collapse
Affiliation(s)
- Sriram Satagopan
- Department of Microbiology, The Ohio State University, Columbus, OH, USA
| | - F Robert Tabita
- Department of Microbiology, The Ohio State University, Columbus, OH, USA
| |
Collapse
|
10
|
Wrighton KC, Castelle CJ, Varaljay VA, Satagopan S, Brown CT, Wilkins MJ, Thomas BC, Sharon I, Williams KH, Tabita FR, Banfield JF. RubisCO of a nucleoside pathway known from Archaea is found in diverse uncultivated phyla in bacteria. ISME J 2016; 10:2702-2714. [PMID: 27137126 PMCID: PMC5113843 DOI: 10.1038/ismej.2016.53] [Citation(s) in RCA: 69] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/25/2015] [Revised: 02/29/2016] [Accepted: 03/04/2016] [Indexed: 11/23/2022]
Abstract
Metagenomic studies recently uncovered form II/III RubisCO genes, originally thought to only occur in archaea, from uncultivated bacteria of the candidate phyla radiation (CPR). There are no isolated CPR bacteria and these organisms are predicted to have limited metabolic capacities. Here we expand the known diversity of RubisCO from CPR lineages. We report a form of RubisCO, distantly similar to the archaeal form III RubisCO, in some CPR bacteria from the Parcubacteria (OD1), WS6 and Microgenomates (OP11) phyla. In addition, we significantly expand the Peregrinibacteria (PER) II/III RubisCO diversity and report the first II/III RubisCO sequences from the Microgenomates and WS6 phyla. To provide a metabolic context for these RubisCOs, we reconstructed near-complete (>93%) PER genomes and the first closed genome for a WS6 bacterium, for which we propose the phylum name Dojkabacteria. Genomic and bioinformatic analyses suggest that the CPR RubisCOs function in a nucleoside pathway similar to that proposed in Archaea. Detection of form II/III RubisCO and nucleoside metabolism gene transcripts from a PER supports the operation of this pathway in situ. We demonstrate that the PER form II/III RubisCO is catalytically active, fixing CO2 to physiologically complement phototrophic growth in a bacterial photoautotrophic RubisCO deletion strain. We propose that the identification of these RubisCOs across a radiation of obligately fermentative, small-celled organisms hints at a widespread, simple metabolic platform in which ribose may be a prominent currency.
Collapse
Affiliation(s)
- Kelly C Wrighton
- Department of Microbiology, The Ohio State University, Columbus, OH, USA
| | - Cindy J Castelle
- Department of Earth and Planetary Science, UC Berkeley, Berkeley, CA, USA
| | - Vanessa A Varaljay
- Department of Microbiology, The Ohio State University, Columbus, OH, USA
| | - Sriram Satagopan
- Department of Microbiology, The Ohio State University, Columbus, OH, USA
| | | | - Michael J Wilkins
- Department of Microbiology, The Ohio State University, Columbus, OH, USA.,School of Earth Sciences, The Ohio State University, Columbus, OH, USA
| | - Brian C Thomas
- Department of Earth and Planetary Science, UC Berkeley, Berkeley, CA, USA
| | - Itai Sharon
- Department of Earth and Planetary Science, UC Berkeley, Berkeley, CA, USA
| | - Kenneth H Williams
- Earth Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - F Robert Tabita
- Department of Microbiology, The Ohio State University, Columbus, OH, USA
| | - Jillian F Banfield
- Department of Earth and Planetary Science, UC Berkeley, Berkeley, CA, USA.,Department of Environmental Science, Policy, and Management, University of California, Berkeley, CA, USA
| |
Collapse
|
11
|
Varaljay VA, Satagopan S, North JA, Witte B, Dourado MN, Anantharaman K, Arbing MA, McCann SH, Oremland RS, Banfield JF, Wrighton KC, Tabita FR. Functional metagenomic selection of ribulose 1, 5-bisphosphate carboxylase/oxygenase from uncultivated bacteria. Environ Microbiol 2016; 18:1187-99. [PMID: 26617072 PMCID: PMC10035430 DOI: 10.1111/1462-2920.13138] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2015] [Revised: 11/17/2015] [Accepted: 11/17/2015] [Indexed: 01/29/2023]
Abstract
Ribulose 1,5-bisphosphate carboxylase/oxygenase (RubisCO) is a critical yet severely inefficient enzyme that catalyses the fixation of virtually all of the carbon found on Earth. Here, we report a functional metagenomic selection that recovers physiologically active RubisCO molecules directly from uncultivated and largely unknown members of natural microbial communities. Selection is based on CO2 -dependent growth in a host strain capable of expressing environmental deoxyribonucleic acid (DNA), precluding the need for pure cultures or screening of recombinant clones for enzymatic activity. Seventeen functional RubisCO-encoded sequences were selected using DNA extracted from soil and river autotrophic enrichments, a photosynthetic biofilm and a subsurface groundwater aquifer. Notably, three related form II RubisCOs were recovered which share high sequence similarity with metagenomic scaffolds from uncultivated members of the Gallionellaceae family. One of the Gallionellaceae RubisCOs was purified and shown to possess CO2 /O2 specificity typical of form II enzymes. X-ray crystallography determined that this enzyme is a hexamer, only the second form II multimer ever solved and the first RubisCO structure obtained from an uncultivated bacterium. Functional metagenomic selection leverages natural biological diversity and billions of years of evolution inherent in environmental communities, providing a new window into the discovery of CO2 -fixing enzymes not previously characterized.
Collapse
Affiliation(s)
- Vanessa A. Varaljay
- Department of Microbiology, The Ohio State University, Columbus, OH 43210, USA
| | - Sriram Satagopan
- Department of Microbiology, The Ohio State University, Columbus, OH 43210, USA
| | - Justin A. North
- Department of Microbiology, The Ohio State University, Columbus, OH 43210, USA
| | - Brian Witte
- The Botanical Research Institute of Texas, Fort Worth, TX 76107, USA
| | | | - Karthik Anantharaman
- Department of Earth and Planetary Science, University of California, Berkeley, CA 94720, USA
| | - Mark A. Arbing
- Protein Expression Technology Center, UCLA-DOE Institute, University of California, Los Angeles, CA 90095, USA
| | | | | | - Jillian F. Banfield
- Department of Earth and Planetary Science, University of California, Berkeley, CA 94720, USA
| | - Kelly C. Wrighton
- Department of Microbiology, The Ohio State University, Columbus, OH 43210, USA
| | - F. Robert Tabita
- Department of Microbiology, The Ohio State University, Columbus, OH 43210, USA
- For correspondence. ; Tel. +1 614 292 4297; Fax: +1 614 292 6337
| |
Collapse
|
12
|
Dey S, North JA, Sriram J, Evans BS, Tabita FR. In Vivo Studies in Rhodospirillum rubrum Indicate That Ribulose-1,5-bisphosphate Carboxylase/Oxygenase (Rubisco) Catalyzes Two Obligatorily Required and Physiologically Significant Reactions for Distinct Carbon and Sulfur Metabolic Pathways. J Biol Chem 2015; 290:30658-68. [PMID: 26511314 DOI: 10.1074/jbc.m115.691295] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2015] [Indexed: 12/19/2022] Open
Abstract
All organisms possess fundamental metabolic pathways to ensure that needed carbon and sulfur compounds are provided to the cell in the proper chemical form and oxidation state. For most organisms capable of using CO2 as sole source of carbon, ribulose-1,5-bisphosphate (RuBP) carboxylase/oxygenase (Rubisco) catalyzes primary carbon dioxide assimilation. In addition, sulfur salvage pathways are necessary to ensure that key sulfur-containing compounds are both available and, where necessary, detoxified in the cell. Using knock-out mutations and metabolomics in the bacterium Rhodospirillum rubrum, we show here that Rubisco concurrently catalyzes key and essential reactions for seemingly unrelated but physiologically essential central carbon and sulfur salvage metabolic pathways of the cell. In this study, complementation and mutagenesis studies indicated that representatives of all known extant functional Rubisco forms found in nature are capable of simultaneously catalyzing reactions required for both CO2-dependent growth as well as growth using 5-methylthioadenosine as sole sulfur source under anaerobic photosynthetic conditions. Moreover, specific inactivation of the CO2 fixation reaction did not affect the ability of Rubisco to support anaerobic 5-methylthioadenosine metabolism, suggesting that the active site of Rubisco has evolved to ensure that this enzyme maintains both key functions. Thus, despite the coevolution of both functions, the active site of this protein may be differentially modified to affect only one of its key functions.
Collapse
Affiliation(s)
- Swati Dey
- From the Department of Microbiology, The Ohio State University, Columbus, Ohio 43210 and
| | - Justin A North
- From the Department of Microbiology, The Ohio State University, Columbus, Ohio 43210 and
| | - Jaya Sriram
- From the Department of Microbiology, The Ohio State University, Columbus, Ohio 43210 and
| | - Bradley S Evans
- the Donald Danforth Plant Science Center, St. Louis, Missouri, 63132
| | - F Robert Tabita
- From the Department of Microbiology, The Ohio State University, Columbus, Ohio 43210 and
| |
Collapse
|
13
|
Kreel NE, Tabita FR. Serine 363 of a Hydrophobic Region of Archaeal Ribulose 1,5-Bisphosphate Carboxylase/Oxygenase from Archaeoglobus fulgidus and Thermococcus kodakaraensis Affects CO2/O2 Substrate Specificity and Oxygen Sensitivity. PLoS One 2015; 10:e0138351. [PMID: 26381513 PMCID: PMC4575112 DOI: 10.1371/journal.pone.0138351] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2015] [Accepted: 08/28/2015] [Indexed: 11/18/2022] Open
Abstract
Archaeal ribulose 1, 5-bisphospate carboxylase/oxygenase (RubisCO) is differentiated from other RubisCO enzymes and is classified as a form III enzyme, as opposed to the form I and form II RubisCOs typical of chemoautotrophic bacteria and prokaryotic and eukaryotic phototrophs. The form III enzyme from archaea is particularly interesting as several of these proteins exhibit unusual and reversible sensitivity to molecular oxygen, including the enzyme from Archaeoglobus fulgidus. Previous studies with A. fulgidus RbcL2 had shown the importance of Met-295 in oxygen sensitivity and pointed towards the potential significance of another residue (Ser-363) found in a hydrophobic pocket that is conserved in all RubisCO proteins. In the current study, further structure/function studies have been performed focusing on Ser-363 of A. fulgidus RbcL2; various changes in this and other residues of the hydrophobic pocket point to and definitively establish the importance of Ser-363 with respect to interactions with oxygen. In addition, previous findings had indicated discrepant CO2/O2 specificity determinations of the Thermococcus kodakaraensis RubisCO, a close homolog of A. fulgidus RbcL2. It is shown here that the T. kodakaraensis enzyme exhibits a similar substrate specificity as the A. fulgidus enzyme and is also oxygen sensitive, with equivalent residues involved in oxygen interactions.
Collapse
Affiliation(s)
- Nathan E. Kreel
- The Ohio State University Biochemistry Program, The Ohio State University, 484 West 12th Avenue, Columbus, Ohio, 43210–1292, United States of America
| | - F. Robert Tabita
- The Ohio State University Biochemistry Program, The Ohio State University, 484 West 12th Avenue, Columbus, Ohio, 43210–1292, United States of America
- Department of Microbiology, The Ohio State University, 484 West 12th Avenue, Columbus, Ohio, 43210–1292, United States of America
| |
Collapse
|
14
|
Farmer RM, Tabita FR. Phosphoribulokinase mediates nitrogenase-induced carbon dioxide fixation gene repression in Rhodobacter sphaeroides. Microbiology (Reading) 2015; 161:2184-91. [PMID: 26306848 PMCID: PMC4806589 DOI: 10.1099/mic.0.000160] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
In many organisms there is a balance between carbon and nitrogen metabolism. These observations extend to the nitrogen-fixing, nonsulfur purple bacteria, which have the classic family of P(II) regulators that coordinate signals of carbon and nitrogen status to regulate nitrogen metabolism. Curiously, these organisms also possess a reverse mechanism to regulate carbon metabolism based on cellular nitrogen status. In this work, studies in Rhodobacter sphaeroides firmly established that the activity of the enzyme that catalyses nitrogen fixation, nitrogenase, induces a signal that leads to repression of genes encoding enzymes of the Calvin–Benson–Bassham (CBB) CO2 fixation pathway. Additionally, genetic and metabolomic experiments revealed that NADH-activated phosphoribulokinase is an intermediate in the signalling pathway. Thus, nitrogenase activity appears to be linked to cbb gene repression through phosphoribulokinase.
Collapse
Affiliation(s)
- Ryan M Farmer
- Department of Microbiology, The Ohio State University, 484 West 12th Avenue, Columbus, OH 43210-1292, USA
| | - F Robert Tabita
- Department of Microbiology, The Ohio State University, 484 West 12th Avenue, Columbus, OH 43210-1292, USA
| |
Collapse
|
15
|
Dangel AW, Tabita FR. Amino acid substitutions in the transcriptional regulator CbbR lead to constitutively active CbbR proteins that elevate expression of the cbb CO2 fixation operons in Ralstonia eutropha (Cupriavidus necator) and identify regions of CbbR necessary for gene activation. Microbiology (Reading) 2015; 161:1816-1829. [PMID: 26296349 DOI: 10.1099/mic.0.000131] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
CbbR is a LysR-type transcriptional regulator that activates expression of the operons containing (cbb) genes that encode the CO2 fixation pathway enzymes in Ralstonia eutropha (Cupriavidus necator) under autotrophic growth conditions. The cbb operons are stringently downregulated during chemoheterotrophic growth on organic acids such as malate. CbbR constitutive proteins (CbbR*s), typically with single amino acid substitutions, were selected and isolated that activate expression of the cbb operons under chemoheterotrophic growth conditions. A large set of CbbR*s from all major domains of the CbbR molecule were identified, except for the DNA-binding domain. The level of gene expression conferred for many of these CbbR*s under autotrophic growth was greater than that conferred by wild-type CbbR. Several of these CbbR*s increase transcription two- to threefold more than wild-type CbbR. One particular CbbR*, a truncated protein, was useful in identifying the regions of CbbR that are necessary for transcriptional activation and, by logical extension, necessary for interaction with RNA polymerase. The reductive assimilation of carbon via CO2 fixation is an important step in the cost-effective production of useful biological compounds. Enhancing CO2 fixation in Ralstonia eutropha through greater transcriptional activation of the cbb operons could prove advantageous, and the use of CbbR*s is one way to enhance product formation.
Collapse
Affiliation(s)
- Andrew W Dangel
- Department of Microbiology, The Ohio State University, 484 West 12th Avenue, Columbus, OH 43210-1292, USA
| | - F Robert Tabita
- Department of Microbiology, The Ohio State University, 484 West 12th Avenue, Columbus, OH 43210-1292, USA
| |
Collapse
|
16
|
Satagopan S, Chan S, Perry LJ, Tabita FR. Structure-function studies with the unique hexameric form II ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) from Rhodopseudomonas palustris. J Biol Chem 2014; 289:21433-50. [PMID: 24942737 DOI: 10.1074/jbc.m114.578625] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The first x-ray crystal structure has been solved for an activated transition-state analog-bound form II ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco). This enzyme, from Rhodopseudomonas palustris, assembles as a unique hexamer with three pairs of catalytic large subunit homodimers around a central 3-fold symmetry axis. This oligomer arrangement is unique among all known Rubisco structures, including the form II homolog from Rhodospirillum rubrum. The presence of a transition-state analog in the active site locked the activated enzyme in a "closed" conformation and revealed the positions of critical active site residues during catalysis. Functional roles of two form II-specific residues (Ile(165) and Met(331)) near the active site were examined via site-directed mutagenesis. Substitutions at these residues affect function but not the ability of the enzyme to assemble. Random mutagenesis and suppressor selection in a Rubisco deletion strain of Rhodobacter capsulatus identified a residue in the amino terminus of one subunit (Ala(47)) that compensated for a negative change near the active site of a neighboring subunit. In addition, substitution of the native carboxyl-terminal sequence with the last few dissimilar residues from the related R. rubrum homolog increased the enzyme's kcat for carboxylation. However, replacement of a longer carboxyl-terminal sequence with termini from either a form III or a form I enzyme, which varied both in length and sequence, resulted in complete loss of function. From these studies, it is evident that a number of subtle interactions near the active site and the carboxyl terminus account for functional differences between the different forms of Rubiscos found in nature.
Collapse
Affiliation(s)
- Sriram Satagopan
- From the Department of Microbiology, The Ohio State University, Columbus, Ohio 43210-1292 and
| | - Sum Chan
- UCLA-Department of Energy (DOE) Institute for Genomics and Proteomics, UCLA, Los Angeles, California 90095-1570
| | - L Jeanne Perry
- UCLA-Department of Energy (DOE) Institute for Genomics and Proteomics, UCLA, Los Angeles, California 90095-1570
| | - F Robert Tabita
- From the Department of Microbiology, The Ohio State University, Columbus, Ohio 43210-1292 and
| |
Collapse
|
17
|
Farmer RM, Laguna R, Panescu J, McCoy A, Logsdon B, Zianni M, Moskvin OV, Gomelsky M, Tabita FR. Altered residues in key proteins influence the expression and activity of the nitrogenase complex in an adaptive CO2 fixation-deficient mutant strain of Rhodobacter sphaeroides. Microbiology (Reading) 2014; 160:198-208. [PMID: 24126349 DOI: 10.1099/mic.0.073031-0] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Previously, the RubisCO-compromised spontaneous adaptive Rhodobacter sphaeroides mutant, strain 16PHC, was shown to derepress the expression of genes that encode the nitrogenase complex under normal repressive conditions. As a result of this adaptation, the active nitrogenase complex restored redox balance, thus allowing strain 16PHC to grow under photoheterotrophic conditions in the absence of an exogenous electron acceptor. A combination of whole genome pyrosequencing and whole genome microarray analyses was employed to identify possible loci responsible for the observed phenotype. Mutations were found in two genes, glnA and nifA, whose products are involved in the regulatory cascade that controls nitrogenase complex gene expression. In addition, a nucleotide reversion within the nifK gene, which encodes a subunit of the nitrogenase complex, was also identified. Subsequent genetic, physiological and biochemical studies revealed alterations that led to derepression of the synthesis of an active nitrogenase complex in strain 16PHC.
Collapse
Affiliation(s)
- Ryan M. Farmer
- Department of Microbiology, Ohio State University, 484 West 12th Avenue, Columbus, OH 43210, USA
| | - Rick Laguna
- Department of Microbiology, Ohio State University, 484 West 12th Avenue, Columbus, OH 43210, USA
| | - Jenny Panescu
- Plant-Microbe Genomics Facility, Ohio State University, 484 West 12th Avenue, Columbus, OH 43210, USA
| | - Anthony McCoy
- Plant-Microbe Genomics Facility, Ohio State University, 484 West 12th Avenue, Columbus, OH 43210, USA
| | - Beth Logsdon
- Plant-Microbe Genomics Facility, Ohio State University, 484 West 12th Avenue, Columbus, OH 43210, USA
| | - Mike Zianni
- Plant-Microbe Genomics Facility, Ohio State University, 484 West 12th Avenue, Columbus, OH 43210, USA
| | - Oleg V. Moskvin
- Department of Molecular Biology, University of Wyoming, Laramie, WY 82071, USA
| | - Mark Gomelsky
- Department of Molecular Biology, University of Wyoming, Laramie, WY 82071, USA
| | - F. Robert Tabita
- Plant-Microbe Genomics Facility, Ohio State University, 484 West 12th Avenue, Columbus, OH 43210, USA
- Department of Microbiology, Ohio State University, 484 West 12th Avenue, Columbus, OH 43210, USA
| |
Collapse
|
18
|
Warlick BPE, Imker HJ, Sriram J, Tabita FR, Gerlt JA. Mechanistic diversity in the RuBisCO superfamily: RuBisCO from Rhodospirillum rubrum is not promiscuous for reactions catalyzed by RuBisCO-like proteins. Biochemistry 2012; 51:9470-9. [PMID: 23110715 DOI: 10.1021/bi301311t] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
d-Ribulose 1,5-bisphosphate carboxylase/oxygenases (RuBisCOs) are promiscuous, catalyzing not only carboxylation and oxygenation of d-ribulose 1,5-bisphosphate but also other promiscuous, presumably nonphysiological, reactions initiated by abstraction of the 3-proton of d-ribulose 1,5-bisphosphate. Also, RuBisCO has homologues that do not catalyze carboxylation; these are designated RuBisCO-like proteins or RLPs. Members of the two families of RLPs catalyze reactions in the recycling of 5'-methylthioadenosine (MTA) generated by polyamine synthesis: (1) the 2,3-diketo-5-methylthiopentane 1-phosphate (DK-MTP 1-P) "enolase" reaction in the well-known "methionine salvage" pathway in Bacillus sp. and (2) the 5-methylthio-d-ribulose 1-phosphate (MTRu 1-P) 1,3-isomerase reaction in the recently discovered "MTA-isoprenoid shunt" that generates 1-deoxy-d-xylulose 5-phosphate for nonmevalonate isoprene synthesis in Rhodospirillum rubrum. We first studied the structure and reactivity of DK-MTP 1-P that was reported to decompose rapidly [Ashida, H., Saito, Y., Kojima, C., and Yokota, A. (2008) Biosci., Biotechnol., Biochem. 72, 959-967]. The 2-carbonyl group of DK-MTP 1-P is rapidly hydrated and can undergo enolization both nonenzymatically and enzymatically via the small amount of unhydrated material that is present. We then examined the ability of RuBisCO from R. rubrum to catalyze both of the RLP-catalyzed reactions. Contrary to a previous report [Ashida, H., Saito, Y., Kojima, C., Kobayashi, K., Ogasawara, N., and Yokota, A. (2003) Science 302, 286-290], we were unable to confirm that this RuBisCO catalyzes the DK-MTP 1-P "enolase" reaction either in vitro or in vivo. We also determined that this RuBisCO does not catalyze the MTRu 1-P 1,3-isomerase reaction in vitro. Thus, although RuBisCOs can be functionally promiscuous, RuBisCO from R. rubrum is not promiscuous for either of the known RLP-catalyzed reactions.
Collapse
Affiliation(s)
- Benjamin P E Warlick
- Department of Biochemistry, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | | | | | | | | |
Collapse
|
19
|
Warlick BP, Evans BS, Erb TJ, Ramagopal UA, Sriram J, Imker HJ, Sauder JM, Bonanno JB, Burley SK, Tabita FR, Almo SC, Sweedler JS, Gerlt JA. 1-methylthio-D-xylulose 5-phosphate methylsulfurylase: a novel route to 1-deoxy-D-xylulose 5-phosphate in Rhodospirillum rubrum. Biochemistry 2012; 51:8324-6. [PMID: 23035785 DOI: 10.1021/bi301215g] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Rhodospirillum rubrum produces 5-methylthioadenosine (MTA) from S-adenosylmethionine in polyamine biosynthesis; however, R. rubrum lacks the classical methionine salvage pathway. Instead, MTA is converted to 5-methylthio-d-ribose 1-phosphate (MTR 1-P) and adenine; MTR 1-P is isomerized to 1-methylthio-d-xylulose 5-phosphate (MTXu 5-P) and reductively dethiomethylated to 1-deoxy-d-xylulose 5-phosphate (DXP), an intermediate in the nonmevalonate isoprenoid pathway [Erb, T. J., et al. (2012) Nat. Chem. Biol., in press]. Dethiomethylation, a novel route to DXP, is catalyzed by MTXu 5-P methylsulfurylase. An active site Cys displaces the enolate of DXP from MTXu 5-P, generating a methyl disulfide intermediate.
Collapse
Affiliation(s)
- Benjamin P Warlick
- Department of Biochemistry, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
20
|
Joshi GS, Bobst CE, Tabita FR. Unravelling the regulatory twist--regulation of CO2 fixation in Rhodopseudomonas palustris CGA010 mediated by atypical response regulator(s). Mol Microbiol 2011; 80:756-71. [PMID: 21362064 DOI: 10.1111/j.1365-2958.2011.07606.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
In Rhodopseudomonas palustris CGA010, the LysR type regulator, CbbR, specifically controls transcription of the cbbLS genes encoding form I RubisCO. Previous genetic and physiological studies had indicated that a unique two-component (CbbRRS) system influences CbbR-mediated cbbLS transcription under conditions where CO(2) is the sole carbon source. In this study, we have established direct protein-protein interactions between the response regulators of the CbbRRS system and CbbR, using a variety of techniques. The bacterial two-hybrid system established a specific interaction between CbbR and CbbRR1 (response regulator 1 of the CbbRRS system), confirmed in vitro by chemical cross-linking. In addition, both response regulators (CbbRR1 and CbbRR2) played distinct roles in influencing the CbbR-cbbLS promoter interactions in gel mobility shift assays. CbbRR1 increased the binding affinity of CbbR at the cbb(I) promoter three- to fivefold while CbbRR2 appeared to stabilize CbbR binding. Specific interactions were further supported by surface plasmon resonance (SPR) analyses. In total, the results suggested that both response regulators, with no discernible DNA-binding domains, must interact with CbbR to influence cbbLS expression. Thus the CbbRRS system provides an additional level of transcriptional control beyond CbbR alone, and appears to be significant for potentially fine-tuning cbbLS expression in Rps. palustris.
Collapse
Affiliation(s)
- Gauri S Joshi
- Department of Microbiology, The Ohio State University, 484 West 12th Avenue, Columbus, OH 43210-1292, USA
| | | | | |
Collapse
|
21
|
Laguna R, Tabita FR, Alber BE. Acetate-dependent photoheterotrophic growth and the differential requirement for the Calvin-Benson-Bassham reductive pentose phosphate cycle in Rhodobacter sphaeroides and Rhodopseudomonas palustris. Arch Microbiol 2010; 193:151-4. [PMID: 21104179 DOI: 10.1007/s00203-010-0652-y] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2010] [Revised: 10/29/2010] [Accepted: 11/02/2010] [Indexed: 10/18/2022]
Abstract
Rhodobacter sphaeroides ribulose-1,5-bisphosphate carboxylase/oxygenase (RubisCO)-deletion strain 16 was capable of photoheterotrophic growth with acetate, while Rhodopseudomonas palustris RubisCO-deletion strain 2040 could not grow under these conditions. The reason for this difference lies in the fact that Rba. sphaeroides and Rps. palustris use different pathways for acetate assimilation, the ethylmalonyl-CoA pathway, and glyoxylate-bypass cycle, respectively. The ethylmalonyl-CoA pathway is distinct from the glyoxylate cycle as one molecule of CO(2) and one molecule of HCO(3) (-) per three molecules of acetyl-CoA are co-assimilated to form two malate molecules. The glyoxylate cycle directly converts two acetyl-CoA molecules to malate. Each pathway, therefore, also dictates at what point, CO(2) and reductant are consumed, thereby determining the requirement for the Calvin-Benson-Bassham reductive pentose phosphate cycle.
Collapse
Affiliation(s)
- Rick Laguna
- Department of Microbiology, The Ohio State University, 484 West 12th Avenue, Columbus, OH 43210, USA
| | | | | |
Collapse
|
22
|
Rizk ML, Laguna R, Smith KM, Tabita FR, Liao JC. Redox homeostasis phenotypes in RubisCO-deficient Rhodobacter sphaeroides via ensemble modeling. Biotechnol Prog 2010; 27:15-22. [DOI: 10.1002/btpr.506] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2010] [Revised: 05/12/2010] [Indexed: 11/06/2022]
|
23
|
Satagopan S, Scott SS, Smith TG, Tabita FR. A Rubisco mutant that confers growth under a normally "inhibitory" oxygen concentration. Biochemistry 2009; 48:9076-83. [PMID: 19705820 DOI: 10.1021/bi9006385] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Ribulose-1,5-bisphosphate (RuBP) carboxylase/oxygenase (Rubisco) is a globally significant biocatalyst that facilitates the removal and sequestration of CO2 from the biosphere. Rubisco-catalyzed CO2 reduction thus provides virtually all of the organic carbon utilized by living organisms. Despite catalyzing the rate-limiting step of photosynthetic and chemoautotrophic CO2 assimilation, Rubisco is markedly inefficient as the competition between O2 and CO2 for the same substrate limits the ability of aerobic organisms to obtain maximum amounts of organic carbon for CO2-dependent growth. Random and site-directed mutagenesis procedures were coupled with genetic selection to identify an "oxygen-insensitive" mutant cyanobacterial (Synechococcus sp. strain PCC 6301) Rubisco that allowed for CO2-dependent growth of a host bacterium at an oxygen concentration that inhibited growth of the host containing wild-type Synechococcus Rubisco. The mutant substitution, A375V, was identified as an intragenic suppressor of D103V, a negative mutant enzyme incapable of supporting autotrophic growth. Ala-375 (Ala-378 of spinach Rubisco) is a conserved residue in all form I (plant-like) Rubiscos. Structure-function analyses indicate that the A375V substitution decreased the enzyme's oxygen sensitivity (and not CO2/O2 specificity), possibly by rearranging a network of interactions in a fairly conserved hydrophobic pocket near the active site. These studies point to the potential of engineering plants and other significant aerobic organisms to fix CO2 unfettered by the presence of O2.
Collapse
Affiliation(s)
- Sriram Satagopan
- Department of Microbiology and the Plant Molecular Biology/Biotechnology Program, The Ohio State University, 484 West 12th Avenue, Columbus, Ohio 43210-1292, USA
| | | | | | | |
Collapse
|
24
|
Dangel AW, Tabita FR. Protein-protein interactions between CbbR and RegA (PrrA), transcriptional regulators of the cbb operons of Rhodobacter sphaeroides. Mol Microbiol 2008; 71:717-29. [PMID: 19077171 DOI: 10.1111/j.1365-2958.2008.06558.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
CbbR and RegA (PrrA) are transcriptional regulators of the cbb(I) and cbb(II) (Calvin-Benson-Bassham CO(2) fixation pathway) operons of Rhodobacter sphaeroides. Both proteins interact specifically with promoter sequences of the cbb operons. RegA has four DNA binding sites within the cbb(I) promoter region, with the CbbR binding site and RegA binding site 1 overlapping each other. This study demonstrated that CbbR and RegA interact and form a discrete complex in vitro, as illustrated by gel mobility shift experiments, direct isolation of the proteins from DNA complexes, and chemical cross-linking analyses. For CbbR/RegA interactions to occur, CbbR must be bound to the DNA, with the ability of CbbR to bind the cbb(I) promoter enhanced by RegA. Conversely, interactions with CbbR did not require RegA to bind the cbb(I) promoter. RegA itself formed incrementally larger multimeric complexes with DNA as the concentration of RegA increased. The presence of RegA binding sites 1, 2 and 3 promoted RegA/DNA binding at significantly lower concentrations of RegA than when RegA binding site 3 was not present in the cbb(I) promoter. These studies support the premise that both CbbR and RegA are necessary for optimal transcription of the cbb(I) operon genes of R. sphaeroides.
Collapse
Affiliation(s)
- Andrew W Dangel
- Department of Microbiology and Plant Molecular Biology/Biotechnology Program, The Ohio State University, 484 West 12th Avenue, Columbus, OH 43210-1292, USA
| | | |
Collapse
|
25
|
Imker HJ, Singh J, Warlick BP, Tabita FR, Gerlt JA. Mechanistic diversity in the RuBisCO superfamily: a novel isomerization reaction catalyzed by the RuBisCO-like protein from Rhodospirillum rubrum. Biochemistry 2008; 47:11171-3. [PMID: 18826254 DOI: 10.1021/bi801685f] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Some homologues of D-ribulose 1,5-bisphosphate carboxylase/oxygenase (RuBisCO) do not catalyze carboxylation and are designated RuBisCO-like proteins (RLPs). The RLP from Rhodospirillum rubrum (gi:83593333) catalyzes a novel isomerization reaction (overall 1,3-proton transfer reaction; likely, two 1,2-proton transfer reactions) that converts 5-methylthio-D-ribulose 1-phosphate to a 3:1 mixture of 1-methylthioxylulose 5-phosphate and 1-methylthioribulose 5-phosphate. Disruption of the gene encoding the RLP abolishes the ability of R. rubrum to utilize 5'-methylthioadenosine as a sole sulfur source, implicating a new, as-yet-uncharacterized, pathway for sulfur salvage.
Collapse
Affiliation(s)
- Heidi J Imker
- Department of Microbiology and Plant Cellular and Molecular Biology Department/Plant Molecular Biology/Biotechnology Program, The Ohio State University, 484 West 12th Avenue, Columbus, Ohio 43210, USA
| | | | | | | | | |
Collapse
|
26
|
Tabita FR, Satagopan S, Hanson TE, Kreel NE, Scott SS. Distinct form I, II, III, and IV Rubisco proteins from the three kingdoms of life provide clues about Rubisco evolution and structure/function relationships. J Exp Bot 2008; 59:1515-24. [PMID: 18281717 DOI: 10.1093/jxb/erm361] [Citation(s) in RCA: 219] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
There are four forms of ribulose 1,5-bisphosphate carboxylase/oxygenase (Rubisco) found in nature. Forms I, II, and III catalyse the carboxylation and oxygenation of ribulose 1,5-bisphosphate, while form IV, also called the Rubisco-like protein (RLP), does not catalyse either of these reactions. There appear to be six different clades of RLP. Although related to bona fide Rubisco proteins at the primary sequence and tertiary structure levels, RLP from two of these clades is known to perform other functions in the cell. Forms I, II, and III Rubisco, along with form IV (RLP), are thought to have evolved from a primordial archaeal Rubisco. Structure/function studies with both archaeal form III (methanogen) and form I (cyanobacterial) Rubisco have identified residues that appear to be specifically involved with interactions with molecular oxygen. A specific region of all form I, II, and III Rubisco was identified as being important for these interactions.
Collapse
Affiliation(s)
- F Robert Tabita
- Department of Microbiology, The Ohio State University, 484 West 12th Avenue, Columbus, Ohio 43210-1292, USA.
| | | | | | | | | |
Collapse
|
27
|
John DE, Wang ZA, Liu X, Byrne RH, Corredor JE, López JM, Cabrera A, Bronk DA, Tabita FR, Paul JH. Phytoplankton carbon fixation gene (RuBisCO) transcripts and air-sea CO2 flux in the Mississippi River plume. ISME J 2007; 1:517-31. [DOI: 10.1038/ismej.2007.70] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
|
28
|
Abstract
In cyanobacteria, the RbcX protein enhances the production of Rubisco, the multisubunit enzyme that catalyzes the first step of carbon dioxide fixation in most autotrophic organisms. In this issue of Cell, Saschenbrecker et al. (2007) report that RbcX acts as a specific assembly chaperone that mobilizes the large subunits of Rubisco to a specific oligomeric core that can then combine with the small subunits of Rubisco to form the functional holoenzyme.
Collapse
Affiliation(s)
- F Robert Tabita
- Department of Microbiology and Plant Molecular Biology/Biotechnology Program, The Ohio State University, 484 West 12th Avenue, Columbus, OH 43210-1292 USA.
| |
Collapse
|
29
|
Hoeft SE, Blum JS, Stolz JF, Tabita FR, Witte B, King GM, Santini JM, Oremland RS. Alkalilimnicola ehrlichii sp. nov., a novel, arsenite-oxidizing haloalkaliphilic gammaproteobacterium capable of chemoautotrophic or heterotrophic growth with nitrate or oxygen as the electron acceptor. Int J Syst Evol Microbiol 2007; 57:504-512. [PMID: 17329775 DOI: 10.1099/ijs.0.64576-0] [Citation(s) in RCA: 136] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
A facultative chemoautotrophic bacterium, strain MLHE-1T, was isolated from Mono Lake, an alkaline hypersaline soda lake in California, USA. Cells of strain MLHE-1T were Gram-negative, short motile rods that grew with inorganic electron donors (arsenite, hydrogen, sulfide or thiosulfate) coupled with the reduction of nitrate to nitrite. No aerobic growth was attained with arsenite or sulfide, but hydrogen sustained both aerobic and anaerobic growth. No growth occurred when nitrite or nitrous oxide was substituted for nitrate. Heterotrophic growth was observed under aerobic and anaerobic (nitrate) conditions. Cells of strain MLHE-1T could oxidize but not grow on CO, while CH4 neither supported growth nor was it oxidized. When grown chemoautotrophically, strain MLHE-1T assimilated inorganic carbon via the Calvin–Benson–Bassham reductive pentose phosphate pathway, with the activity of ribulose 1,5-bisphosphate carboxylase (RuBisCO) functioning optimally at 0.1 M NaCl and at pH 7.3. Strain MLHE-1T grew over broad ranges of pH (7.3–10.0; optimum, 9.3), salinity (15–190 g l−1; optimum 30 g l−1) and temperature (13–40 °C; optimum, 30 °C). Phylogenetic analysis of 16S rRNA gene sequences placed strain MLHE-1T in the class Gammaproteobacteria (family Ectothiorhodospiraceae) and most closely related to Alkalispirillum mobile (98.5 %) and Alkalilimnicola halodurans (98.6 %), although none of these three haloalkaliphilic micro-organisms were capable of photoautotrophic growth and only strain MLHE-1T was able to oxidize As(III). On the basis of physiological characteristics and DNA–DNA hybridization data, it is suggested that strain MLHE-1T represents a novel species within the genus Alkalilimnicola for which the name Alkalilimnicola ehrlichii is proposed. The type strain is MLHE-1T (=DSM 17681T=ATCC BAA-1101T). Aspects of the annotated full genome of Alkalilimnicola ehrlichii are discussed in the light of its physiology.
Collapse
Affiliation(s)
- Shelley E Hoeft
- US Geological Survey, 345 Middlefield Road, MS 480, Menlo Park, CA 94025, USA
| | - Jodi Switzer Blum
- US Geological Survey, 345 Middlefield Road, MS 480, Menlo Park, CA 94025, USA
| | - John F Stolz
- Department of Biological Sciences, Duquesne University, Pittsburgh, PA 15282, USA
| | - F Robert Tabita
- Department of Microbiology, The Ohio State University, Columbus, OH 43210, USA
| | - Brian Witte
- Department of Microbiology, The Ohio State University, Columbus, OH 43210, USA
| | - Gary M King
- Darling Marine Center, University of Maine, Walpole, ME 04573, USA
| | | | - Ronald S Oremland
- US Geological Survey, 345 Middlefield Road, MS 480, Menlo Park, CA 94025, USA
| |
Collapse
|
30
|
Kreel NE, Tabita FR. Substitutions at methionine 295 of Archaeoglobus fulgidus ribulose-1,5-bisphosphate carboxylase/oxygenase affect oxygen binding and CO2/O2 specificity. J Biol Chem 2006; 282:1341-51. [PMID: 17074752 DOI: 10.1074/jbc.m609399200] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Archaeoglobus fulgidus RbcL2, a form III ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco), exhibits unique properties not found in other well studied form I and II Rubiscos, such as optimal activity from 83 to 93 degrees C and an extremely high kcat value (23 s-1). More interestingly, this protein is unusual in that exposure or assay in the presence of oxygen and high levels of CO2 resulted in substantial loss (85-90%) of activity compared with assays performed under strictly anaerobic conditions. Kinetic studies indicated that A. fulgidus RbcL2 possesses an unusually high affinity for oxygen (Ki=5 microM); O2 is a competitive inhibitor with respect to CO2, yet the high affinity for O2 presumably accounts for the inability of high levels of CO2 to prevent inhibition. Comparative bioinformatic analyses of available archaeal Rubisco sequences were conducted to provide clues as to why the RbcL2 protein might possess such a high affinity for oxygen. These analyses suggested the potential importance of several unique residues, as did additional analyses within the context of available form I-III Rubisco structures. One residue unique to archaeal proteins (Met-295) was of particular interest because of its proximity to known active-site residues. Recombinant M295D A. fulgidus Rubisco was less sensitive to oxygen compared with the wild-type enzyme. This residue, along with other potential changes in conserved residues of form III Rubiscos, may provide an understanding as to how Rubisco may have evolved to function in the presence of air.
Collapse
Affiliation(s)
- Nathaniel E Kreel
- Department of Microbiology and the Plant Molecular Biology/Biotechnology Program, Ohio State University, Columbus, Ohio 43210-1292, USA
| | | |
Collapse
|
31
|
Romagnoli S, Tabita FR. Phosphotransfer reactions of the CbbRRS three-protein two- component system from Rhodopseudomonas palustris CGA010 appear to be controlled by an internal molecular switch on the sensor kinase. J Bacteriol 2006; 189:325-35. [PMID: 17071758 PMCID: PMC1797408 DOI: 10.1128/jb.01326-06] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The CbbRRS system is an atypical three-protein two-component system that modulates the expression of the cbb(I) CO(2) fixation operon of Rhodopseudomonas palustris, possibly in response to a redox signal. It consists of a membrane-bound hybrid sensor kinase, CbbSR, with a transmitter and receiver domain, and two response regulator proteins, CbbRR1 and CbbRR2. No detectable helix-turn-helix DNA binding domain is associated with either response regulator, but an HPt domain and a second receiver domain are predicted at the C-terminal region of CbbRR1 and CbbRR2, respectively. The abundance of conserved residues predicted to participate in a His-Asp phosphorelay raised the question of their de facto involvement. In this study, the role of the multiple receiver domains was elucidated in vitro by generating site-directed mutants of the putative conserved residues. Distinct phosphorylation patterns were obtained with two truncated versions of the hybrid sensor kinase, CbbSR(T189) and CbbSR(R96) (CbbSR beginning at residues T189 and R96, respectively). These constructs also exhibited substantially different affinities for ATP and phosphorylation stability, which was found to be dependent on a conserved Asp residue (Asp-696) within the kinase receiver domain. Asp-696 also played an important role in defining the specificity of phosphorylation for response regulators CbbRR1 or CbbRR2, and this residue appeared to act in conjunction with residues within the region from Arg-96 to Thr-189 at the N terminus of the sensor kinase. The net effect of concerted interactions at these distinct regions of CbbSR created an internal molecular switch that appears to coordinate a unique branched phosphorelay system.
Collapse
Affiliation(s)
- Simona Romagnoli
- Department of Microbiology, The Ohio State University, Columbus, OH 43210-1292, USA
| | | |
Collapse
|
32
|
Abstract
ATP-citrate lyase (ACL) is an essential enzyme of the reductive tricarboxylic acid (RTCA) pathway of CO(2) assimilation. The RTCA pathway occurs in several groups of autotrophic prokaryotes, including the green sulfur bacteria. ACL catalyzes the coenzyme A (CoA)-dependent and MgATP-dependent cleavage of citrate into oxaloacetate and acetyl-CoA, representing a key step in the RTCA pathway. To characterize this enzyme from the green sulfur bacterium Chlorobium tepidum and determine the role of its two distinct polypeptide chains, recombinant holo-ACL as well as its two individual subunit polypeptides were synthesized in Escherichia coli. The recombinant holoenzyme, prepared from coexpressed large and small ACL genes, and the individual large and small subunit polypeptides, prepared from singly expressed genes, were all purified to homogeneity to high yield. Purified recombinant holo-ACL was isolated at high specific activity, and its k(cat) was comparable to that of previously prepared native C. tepidum ACL. Moreover, the purified recombinant large and small subunit polypeptides were able to reconstitute the holo-ACL in vitro, with activity levels approaching that of recombinant holo-ACL prepared from coexpressed genes. Stoichiometric amounts of each subunit protein were required to maximize the activity and form the most stable structure of reconstituted holo-ACL. These results suggested that this reconstitution system could be used to discern the catalytic role of specific amino acid residues on each subunit. Reconstitution and mutagenesis studies together indicated that residues of each subunit contributed to different aspects of the catalytic mechanism, suggesting that both subunit proteins contribute to the active site of C. tepidum ACL.
Collapse
Affiliation(s)
- Wonduck Kim
- Department of Microbiology, The Ohio State University, 484 12th Ave., Columbus, OH 42310-1292, USA
| | | |
Collapse
|
33
|
Romagnoli S, Tabita FR. A novel three-protein two-component system provides a regulatory twist on an established circuit to modulate expression of the cbbI region of Rhodopseudomonas palustris CGA010. J Bacteriol 2006; 188:2780-91. [PMID: 16585739 PMCID: PMC1446975 DOI: 10.1128/jb.188.8.2780-2791.2006] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
A novel two-component system has been identified in the cbb(I) region of the nonsulfur purple photosynthetic bacterium Rhodopseudomonas palustris. Genes encoding this system, here designated cbbRRS, are juxtaposed between the divergently transcribed transcription activator gene, cbbR, and the form I ribulose-1,5-bisphosphate carboxylase/oxygenase (RubisCO) genes, cbbLS. The three genes of the cbbRRS system represent a variation of the well-known two-component signal transduction systems, as there are a transmembrane hybrid sensor kinase and two response regulators, with no apparent DNA binding domain associated with any of the three proteins encoded by these genes. In this study, we showed that the membrane-bound full-length kinase undergoes autophosphorylation and transfers phosphate to both response regulators. A soluble, truncated version of the kinase was subsequently prepared and found to catalyze phosphorylation of response regulator 1 but not response regulator 2, implying that conformational changes and/or sequence-specific regions of the kinase are important for discriminating between the two response regulators. Analyses indicated that a complex network of control of gene expression must occur, with CbbR required for the expression of the cbbLS genes but dispensable for the synthesis of form II RubisCO (encoded by cbbM). The CbbRRS proteins specifically affected the activity and accumulation of form I RubisCO (CbbLS), as revealed by analyses of nonpolar, unmarked gene deletions. A tentative model of regulation suggested that changes in the phosphotransfer activity of the sensor kinase, possibly in response to a redox metabolic signal, cause modulation of the activity and synthesis of form I RubisCO.
Collapse
Affiliation(s)
- Simona Romagnoli
- Department of Microbiology, The Ohio State University, 484 West 12th Ave., Columbus, OH 43210-1292, USA
| | | |
Collapse
|
34
|
Zianni M, Tessanne K, Merighi M, Laguna R, Tabita FR. Identification of the DNA bases of a DNase I footprint by the use of dye primer sequencing on an automated capillary DNA analysis instrument. J Biomol Tech 2006; 17:103-13. [PMID: 16741237 PMCID: PMC2291779] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
We have adapted the techniques of DNA footprint analysis to an Applied Biosystems 3730 DNA Analyzer. The use of fluorescently labeled primers eliminates the need for radioactively labeled nucleotides, as well as slab gel electrophoresis, and takes advantage of commonly available automated fluorescent capillary electrophoresis instruments. With fluorescently labeled primers and dideoxynucleotide DNA sequencing, we have shown that the terminal base of each digested fragment may be accurately identified with a capillary-based instrument. Polymerase chain reaction (PCR) was performed with a 6FAM-labeled primer to amplify a typical target promoter region. This PCR product was then incubated with a transcriptional activator protein, or bovine serum albumin as a control, and then partially digested with DNase I. A clone of the promoter was sequenced with the Thermo Sequenase Dye Primer Manual Cycle Sequencing kit (USB) and the FAM-labeled primer. Through the use of Genemapper software, the Thermo sequenase and DNasei digestion products were accurately aligned, providing a ready means to assign correct nucleotides to each peak from the DNA footprint. This method was used to characterize the binding of two different transcriptional activator proteins to their respective promoter regions.
Collapse
Affiliation(s)
- Michael Zianni
- Plant-Microbe Genomics Facility, The Ohio State University, Columbus, OH 43210-1292, USA.
| | | | | | | | | |
Collapse
|
35
|
VerBerkmoes NC, Shah MB, Lankford PK, Pelletier DA, Strader MB, Tabb DL, McDonald WH, Barton JW, Hurst GB, Hauser L, Davison BH, Beatty JT, Harwood CS, Tabita FR, Hettich RL, Larimer FW. Determination and comparison of the baseline proteomes of the versatile microbe Rhodopseudomonas palustris under its major metabolic states. J Proteome Res 2006; 5:287-98. [PMID: 16457594 DOI: 10.1021/pr0503230] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Rhodopseudomonas palustris is a purple nonsulfur anoxygenic phototrophic bacterium that is ubiquitous in soil and water. R. palustris is metabolically versatile with respect to energy generation and carbon and nitrogen metabolism. We have characterized and compared the baseline proteome of a R. palustris wild-type strain grown under six metabolic conditions. The methodology for proteome analysis involved protein fractionation by centrifugation, subsequent digestion with trypsin, and analysis of peptides by liquid chromatography coupled with tandem mass spectrometry. Using these methods, we identified 1664 proteins out of 4836 predicted proteins with conservative filtering constraints. A total of 107 novel hypothetical proteins and 218 conserved hypothetical proteins were detected. Qualitative analyses revealed over 311 proteins exhibiting marked differences between conditions, many of these being hypothetical or conserved hypothetical proteins showing strong correlations with different metabolic modes. For example, five proteins encoded by genes from a novel operon appeared only after anaerobic growth with no evidence of these proteins in extracts of aerobically grown cells. Proteins known to be associated with specialized growth states such as nitrogen fixation, photoautotrophic, or growth on benzoate, were observed to be up-regulated under those states.
Collapse
Affiliation(s)
- Nathan C VerBerkmoes
- Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA.
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
36
|
Dangel AW, Gibson JL, Janssen AP, Tabita FR. Residues that influence in vivo and in vitro CbbR function in Rhodobacter sphaeroides and identification of a specific region critical for co-inducer recognition. Mol Microbiol 2005; 57:1397-414. [PMID: 16102008 DOI: 10.1111/j.1365-2958.2005.04783.x] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
CbbR is a LysR-type transcriptional regulator (LTTR) that is required to activate transcription of the cbb operons, responsible for CO2 fixation, in Rhodobacter sphaeroides. LTTR proteins often require a co-inducer to regulate transcription. Previous studies suggested that ribulose 1,5-bisphosphate (RuBP) is a positive effector for CbbR function in this organism. In the current study, RuBP was found to increase the electrophoretic mobility of the CbbR/cbb(I) promoter complex. To define and analyse the co-inducer recognition region of CbbR, constitutively active mutant CbbR proteins were isolated. Under growth conditions that normally maintain transcriptionally inactive cbb operons, the mutant CbbR proteins activated transcription. Fourteen of the constitutively active mutants resulted from a single amino acid substitution. One mutant was derived from amino acid substitutions at two separate residues that appeared to act synergistically. Different mutant proteins showed both sensitivity and insensitivity to RuBP and residues that conferred constitutive transcriptional activity could be highlighted on a three-dimensional model, with several residues unique to CbbR shown to be at locations critical to LTTR function. Many of the constitutive residues clustered in or near two specific loops in the LTTR tertiary structure, corresponding to a proposed site of co-inducer binding.
Collapse
Affiliation(s)
- Andrew W Dangel
- Department of Microbiology and Plant Molecular Biology/Biotechnology Program, The Ohio State University, 484 West 12th Avenue, Columbus, OH 43210-1292, USA
| | | | | | | |
Collapse
|
37
|
Li H, Sawaya MR, Tabita FR, Eisenberg D. Crystal structure of a RuBisCO-like protein from the green sulfur bacterium Chlorobium tepidum. Structure 2005; 13:779-89. [PMID: 15893668 DOI: 10.1016/j.str.2005.02.017] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2004] [Revised: 02/17/2005] [Accepted: 02/19/2005] [Indexed: 11/24/2022]
Abstract
Ribulose 1,5-bisphosphate carboxylase/oxygenase (RuBisCO) catalyzes the incorporation of atmospheric CO(2) into ribulose 1,5-bisphosphate (RuBP). RuBisCOs are classified into four forms based on sequence similarity: forms I, II and III are bona fide RuBisCOs; form IV, also called the RuBisCO-like protein (RLP), lacks several of the substrate binding and catalytic residues and does not catalyze RuBP-dependent CO(2) fixation in vitro. To contribute to understanding the function of RLPs, we determined the crystal structure of the RLP from Chlorobium tepidum. The overall structure of the RLP is similar to the structures of the three other forms of RuBisCO; however, the active site is distinct from those of bona fide RuBisCOs and suggests that the RLP is possibly capable of catalyzing enolization but not carboxylation. Bioinformatic analysis of the protein functional linkages suggests that this RLP coevolved with enzymes of the bacteriochlorophyll biosynthesis pathway and may be involved in processes related to photosynthesis.
Collapse
Affiliation(s)
- Huiying Li
- Department of Chemistry and Biochemistry, Howard Hughes Medical Institute, UCLA-DOE Institute for Genomics and Proteomics, University of California, Los Angeles, Box 951570, Los Angeles, California 90095, USA
| | | | | | | |
Collapse
|
38
|
Abstract
In Rhodobacter capsulatus, genes encoding enzymes of the Calvin-Benson-Bassham reductive pentose phosphate pathway are located in the cbb(I) and cbb(II) operons. Each operon contains a divergently transcribed LysR-type transcriptional activator (CbbR(I) and CbbR(II)) that regulates the expression of its cognate cbb promoter in response to an as yet unidentified effector molecule(s). Both CbbR(I) and CbbR(II) were purified, and the ability of a variety of potential effector molecules to induce changes in their DNA binding properties at their target promoters was assessed. The responses of CbbR(I) and CbbR(II) to potential effectors were not identical. In gel mobility shift assays, the affinity of both CbbR(I) and CbbR(II) for their target promoters was enhanced in the presence of ribulose-1,5-bisphosphate (RuBP), phosphoenolpyruvate, 3-phosphoglycerate, 2-phosphoglycolate. ATP, 2-phosphoglycerate, and KH(2)PO(4) were found to enhance only CbbR(I) binding, while fructose-1,6-bisphosphate enhanced the binding of only CbbR(II). The DNase I footprint of CbbR(I) was reduced in the presence of RuBP, while reductions in the CbbR(II) DNase I footprint were induced by fructose-1,6-bisphosphate, 3-phosphoglycerate, and KH(2)PO(4). The current in vitro results plus recent in vivo studies suggest that CbbR-mediated regulation of cbb transcription is controlled by multiple metabolic signals in R. capsulatus. This control reflects not only intracellular levels of Calvin-Benson-Bassham cycle metabolic intermediates but also the fixed (organic) carbon status and energy charge of the cell.
Collapse
Affiliation(s)
- Padungsri Dubbs
- Department of Microbiology, Mahidol University, Payathai, Thailand
| | | | | |
Collapse
|
39
|
Dubbs JM, Tabita FR. Regulators of nonsulfur purple phototrophic bacteria and the interactive control of CO2 assimilation, nitrogen fixation, hydrogen metabolism and energy generation. FEMS Microbiol Rev 2004; 28:353-76. [PMID: 15449608 DOI: 10.1016/j.femsre.2004.01.002] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
For the metabolically diverse nonsulfur purple phototrophic bacteria, maintaining redox homeostasis requires balancing the activities of energy supplying and energy-utilizing pathways, often in the face of drastic changes in environmental conditions. These organisms, members of the class Alphaproteobacteria, primarily use CO2 as an electron sink to achieve redox homeostasis. After noting the consequences of inactivating the capacity for CO2 reduction through the Calvin-Benson-Bassham (CBB) pathway, it was shown that the molecular control of many additional important biological processes catalyzed by nonsulfur purple bacteria is linked to expression of the CBB genes. Several regulator proteins are involved, with the two component Reg/Prr regulatory system playing a major role in maintaining redox poise in these organisms. Reg/Prr was shown to be a global regulator involved in the coordinate control of a number of metabolic processes including CO2 assimilation, nitrogen fixation, hydrogen metabolism and energy-generation pathways. Accumulating evidence suggests that the Reg/Prr system senses the oxidation/reduction state of the cell by monitoring a signal associated with electron transport. The response regulator RegA/PrrA activates or represses gene expression through direct interaction with target gene promoters where it often works in concert with other regulators that can be either global or specific. For the key CO2 reduction pathway, which clearly triggers whether other redox balancing mechanisms are employed, the ability to activate or inactivate the specific regulator CbbR is of paramount importance. From these studies, it is apparent that a detailed understanding of how diverse regulatory elements integrate and control metabolism will eventually be achieved.
Collapse
Affiliation(s)
- James M Dubbs
- Laboratory of Biotechnology, Chulabhorn Research Institute, Lak Si, Bangkok 10210, Thailand
| | | |
Collapse
|
40
|
Abstract
Several sequencing projects unexpectedly uncovered the presence of genes that encode ribulose 1,5-bisphosphate (RuBP) carboxylase/oxygenase (RubisCO) in anaerobic archaea. RubisCO is the key enzyme of the Calvin-Benson-Bassham (CBB) reductive pentose phosphate pathway, a scheme that does not appear to contribute greatly, if at all, to net CO2 assimilation in these organisms. Recombinant forms of the archaeal enzymes do, however, catalyze a bona fide RuBP-dependent CO2 fixation reaction, and it was recently shown that Methanocaldococcus (Methanococcus) jannaschii and other anaerobic archaea synthesize catalytically active RubisCO in vivo. To complete the CBB pathway, there is a need for an enzyme, i.e., phosphoribulokinase (PRK), to catalyze the formation of RuBP, the substrate for the RubisCO reaction. Homology searches, as well as direct enzymatic assays with M. jannaschii, failed to reveal the presence of PRK. The apparent lack of PRK raised the possibility that either there is an alternative pathway to generate RuBP or RubisCO might use an alternative substrate in vivo. In the present study, direct enzymatic assays performed with alternative substrates and extracts of M. jannsachii provided evidence for a previously uncharacterized pathway for RuBP synthesis from 5-phospho-D-ribose-1-pyrophosphate (PRPP) in M. jannaschii and other methanogenic archaea. Proteins and genes involved in the catalytic conversion of PRPP to RuBP were identified in M. jannaschii (Mj0601) and Methanosarcina acetivorans (Ma2851), and recombinant Ma2851 was active in extracts of Escherichia coli. Thus, in this work we identified a novel means to synthesize the CO2 acceptor and substrate for RubisCO in the absence of a detectable kinase, such as PRK. We suggest that the conversion of PRPP to RuBP might be an evolutional link between purine recycling pathways and the CBB scheme.
Collapse
Affiliation(s)
- Michael W Finn
- Department of Microbiology, The Ohio State University, Columbus, Ohio 43210-1292, USA
| | | |
Collapse
|
41
|
Bobst CE, Tabita FR. The role of cysteine 160 in thiamine diphosphate binding of the Calvin–Benson–Bassham cycle transketolase of Rhodobacter sphaeroides. Arch Biochem Biophys 2004; 426:43-54. [PMID: 15130781 DOI: 10.1016/j.abb.2004.03.027] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2004] [Revised: 03/19/2004] [Indexed: 10/26/2022]
Abstract
The transketolase gene (cbbT) that encodes the Calvin-Benson-Bassham pathway transketolase (CbbT) of Rhodobacter sphaeroides was overexpressed in Escherichia coli and the recombinant protein purified to homogeneity. Like other transketolases, R. sphaeroides CbbT was found to be inactivated in the presence of oxygen. At its optimal pH of 7.8, CbbT displays a specific activity of 37 U/mg, a KR5P of 949 microM, a KXu5P of 11 microM, and a KThDP of 1.8 microM. Cysteine 160, equivalent to Cys159 of the yeast enzyme, is found within the active site and is loosely conserved amongst several sources of transketolase. To investigate the role of cysteine 160 found in the active site of R. sphaeroides CbbT, this residue was targeted for mutagenesis. Cys160 was changed to alanine, serine, aspartate, and glutamate. To compare the effect of these mutations on ThDP binding, spectral techniques were employed in addition to analysis by enzymatic activity. Fluorescence quenching was used to measure both equilibrium binding constants as well as first order rates of binding. The results of these studies indicated that Cys160 played an important and substantial role in cofactor binding, revealing the importance of this loosely conserved residue. In addition, the Cys160 mutants did not appear to alter oxygen-mediated inactivation.
Collapse
Affiliation(s)
- Cedric E Bobst
- The Ohio State Biochemistry Program, The Ohio State University, 484 West 12th Avenue, Columbus, OH 43210-1292, USA
| | | |
Collapse
|
42
|
Smith SA, Tabita FR. Glycine 176 affects catalytic properties and stability of the Synechococcus sp. strain PCC6301 ribulose-1,5-bisphosphate carboxylase/oxygenase. J Biol Chem 2004; 279:25632-7. [PMID: 15067012 DOI: 10.1074/jbc.m401360200] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
A previously described system for biological selection of randomly mutagenized ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) employing the phototrophic bacterium Rhodobacter capsulatus was used to select a catalytically altered form of a cyanobacterial (Synechococcus sp. strain PCC6301) enzyme. This mutant Rubisco, in which conserved glycine 176 was replaced with an aspartate residue, was not able to support CO(2)-dependent growth of the host strain. Site-directed mutant proteins were also constructed, e.g. asparagine and alanine residues replaced the native glycine with the result that these mutant proteins either greatly reduced the ability of R. capsulatus to support growth or had little effect, respectively. Growth phenotypes were consistent with the Rubisco activity levels associated with these proteins, and this was also borne out with purified recombinant proteins. Despite being catalytically challenged, the G176D and G176N mutant proteins were found to exhibit a more favorable interaction with CO(2) than the wild type protein but exhibited a reduced affinity for the substrate ribulose 1,5-bisphosphate. The G176A enzyme differed little from the wild type protein in these properties. None of the mutants had CO(2)/O(2) specificities that differed markedly from the wild type. Further studies taken from the known structure of the Synechococcus Rubisco indicated that substitutions at Gly-176 affected associations between large subunits. Supporting experimental data included an unusual protein concentration-dependent effect on in vitro activity, differences in thermal stability relative to the wild type protein, and aberrant migration on nondenaturing polyacrylamide gels. From these results, it is apparent that residues not directly located within the active site but near large subunit interfaces can affect key kinetic properties of Rubisco. These results suggest that further bioselection protocols (using these proteins as starting material) might yield novel mutant forms of Rubisco that relate to key functional properties.
Collapse
Affiliation(s)
- Stephanie A Smith
- Department of Microbiology and Plant Molecular Biology/Biotechnology Program, The Ohio State University, Columbus, Ohio 43210-1292, USA
| | | |
Collapse
|
43
|
Abstract
This paper presents my personal account of research on CO(2) fixation from when I began these studies as a postdoctoral student in the early 1970s. It traces interests in microbial ribulose bisphosphate carboxylase/oxygenase (Rubisco) and considers early breakthroughs on the isolation, characterization, and significance of this enzyme from nonsulfur purple photosynthetic bacteria and other phototrophic organisms. This article also develops a historical perspective as to how recent efforts may lead to an understanding of molecular mechanisms by which the synthesis of this enzyme and other proteins of the pathway are regulated at the molecular level. In addition, how these studies impinge on the interactive control of CO(2) fixation, along with nitrogen fixation and hydrogen metabolism, is also considered. Finally, CO(2)-fixation studies in green sulfur photosynthetic bacteria and the discovery of the rather surprising Rubisco-like protein are described.
Collapse
Affiliation(s)
- F Robert Tabita
- Department of Microbiology and the Plant Molecular Biology/Biotechnology Program, The Ohio State University, 484 West 12th Avenue, Columbus, OH, 43210-1292, USA,
| |
Collapse
|
44
|
Larimer FW, Chain P, Hauser L, Lamerdin J, Malfatti S, Do L, Land ML, Pelletier DA, Beatty JT, Lang AS, Tabita FR, Gibson JL, Hanson TE, Bobst C, Torres JLTY, Peres C, Harrison FH, Gibson J, Harwood CS. Complete genome sequence of the metabolically versatile photosynthetic bacterium Rhodopseudomonas palustris. Nat Biotechnol 2003; 22:55-61. [PMID: 14704707 DOI: 10.1038/nbt923] [Citation(s) in RCA: 480] [Impact Index Per Article: 22.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2003] [Accepted: 11/03/2003] [Indexed: 01/26/2023]
Abstract
Rhodopseudomonas palustris is among the most metabolically versatile bacteria known. It uses light, inorganic compounds, or organic compounds, for energy. It acquires carbon from many types of green plant-derived compounds or by carbon dioxide fixation, and it fixes nitrogen. Here we describe the genome sequence of R. palustris, which consists of a 5,459,213-base-pair (bp) circular chromosome with 4,836 predicted genes and a plasmid of 8,427 bp. The sequence reveals genes that confer a remarkably large number of options within a given type of metabolism, including three nitrogenases, five benzene ring cleavage pathways and four light harvesting 2 systems. R. palustris encodes 63 signal transduction histidine kinases and 79 response regulator receiver domains. Almost 15% of the genome is devoted to transport. This genome sequence is a starting point to use R. palustris as a model to explore how organisms integrate metabolic modules in response to environmental perturbations.
Collapse
Affiliation(s)
- Frank W Larimer
- Genome Analysis and Systems Modeling, Oak Ridge National Laboratory, One Bethel Valley Rd., Oak Ridge, Tennessee 37831, USA
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
45
|
Abstract
A system for biological selection of randomly mutagenized ribulose 1,5-bisphosphate carboxylase/oxygenase (Rubisco) genes from the cyanobacterium Synechococcus PCC6301 was designed in which a Rubisco deletion mutant of the photosynthetic bacterium Rhodobacter capsulatus served as a host. Trans-complementation with the Synechococcus PCC6301 rbcLS genes enabled anaerobic photoautotrophic growth of the R.capsulatus deletion strain with 5% CO(2), but not with 1.5% CO(2) in the atmosphere, and this strain could not grow under aerobic chemoautotrophic conditions. Phenotypic differences between the R.capsulatus host strain complemented with the wild-type rbcLS genes and transconjugates carrying mutated genes were used to identify mutants that were able to complement to photoautotrophic growth with 1.5% CO(2). These "positive" mutant proteins were unaffected for any measured kinetic properties, with a single exception. A mutant with a valine substitution at phenylalanine 342 had an increased affinity for ribulose-1,5-bisphosphate. Mutants with changes in the affinity for CO(2) were isolated through negative selection, in which mutants incapable of complementing R.capsulatus to photoautotrophic growth with 5% CO(2) were identified. Mutations at aspartate 103 resulted in enzymes that were greatly affected for different kinetic parameters, including an increased K(m) for CO(2). This study demonstrated that random mutagenesis and bioselection procedures could be used to identify mutations that influence important properties of bacterial Rubisco; these residues would not have been identified by other methods.
Collapse
Affiliation(s)
- Stephanie A Smith
- Department of Microbiology, The Ohio State University, 484 West 12th Avenue, Columbus, OH 43210-1292, USA
| | | |
Collapse
|
46
|
Dubbs JM, Tabita FR. Interactions of the cbbII promoter-operator region with CbbR and RegA (PrrA) regulators indicate distinct mechanisms to control expression of the two cbb operons of Rhodobacter sphaeroides. J Biol Chem 2003; 278:16443-50. [PMID: 12601011 DOI: 10.1074/jbc.m211267200] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
In a previous study (Dubbs, J. M., Bird, T. H., Bauer, C. E., and Tabita, F. R. (2000) J. Biol. Chem. 275, 19224-19230), it was demonstrated that the regulators CbbR and RegA (PrrA) interacted with both promoter proximal and promoter distal regions of the form I (cbb(I)) promoter operon specifying genes of the Calvin-Benson-Bassham cycle of Rhodobacter sphaeroides. To determine how these regulators interact with the form II (cbb(II)) promoter, three cbbF(II)::lacZ translational fusion plasmids were constructed containing various lengths of sequence 5' to the cbb(II) operon of R. sphaeroides CAC. Expression of beta-galactosidase was monitored under a variety of growth conditions in both the parental strain and knock-out strains that contain mutations that affect synthesis of CbbR and RegA. The binding sites for both CbbR and RegA were determined by DNase I footprinting. A region of the cbb(II) promoter from +38 to -227 bp contained a CbbR binding site and conferred low level regulated cbb(II) expression. The region from -227 to -1025 bp contained six RegA binding sites and conferred enhanced cbb(II) expression under all growth conditions. Unlike the cbb(I) operon, the region between -227 and -545 bp that contains one RegA binding site, was responsible for the majority of the observed enhancement. Both RegA and CbbR were required for maximal cbb(II) expression. Two potentially novel and specific cbb(II) promoter-binding proteins that did not interact with the cbb(I) promoter region were detected in crude extracts of R. sphaeroides. These results, combined with the observation that chemoautotrophic expression of the cbb(I) operon is RegA independent, indicated that the mechanisms controlling cbb(I) and cbb(II) operon expression during chemoautotrophic growth are quite different.
Collapse
Affiliation(s)
- James M Dubbs
- Department of Microbiology, Plant Molecular Biology/Biotechnology Program, The Ohio State University, 484 West 12th Avenue, Columbus, OH 43210-1292, USA
| | | |
Collapse
|
47
|
Abstract
Ribulose 1,5 bisphosphate carboxylase/oxygenase (RubisCO) catalyzes the biological reduction and assimilation of carbon dioxide gas to organic carbon; it is the key enzyme responsible for the bulk of organic matter found on earth. Until recently it was believed that there are only two forms of RubisCO, form I and form II. However, the recent completion of several genome-sequencing projects uncovered open reading frames resembling RubisCO in the third domain of life, the archaea. Previous work and homology comparisons suggest that these enzymes represent a third form of RubisCO, form III. While earlier work indicated that two structurally distinct recombinant archaeal RubisCO proteins catalyzed bona fide RubisCO reactions, it was not established that the rbcL genes of anaerobic archaea can be transcribed and translated to an active enzyme in the native organisms. In this report, it is shown not only that Methanococcus jannaschii, Archaeoglobus fulgidus, Methanosarcina acetivorans, and Methanosarcina barkeri possess open reading frames with the residues required for catalysis but also that the RubisCO protein from these archaea accumulates in an active form under normal growth conditions. In addition, the form III RubisCO gene (rbcL) from M. acetivorans was shown to complement RubisCO deletion strains of Rhodobacter capsulatus and Rhodobacter sphaeroides under both photoheterotrophic and photoautotrophic growth conditions. These studies thus indicate for the first time that archaeal form III RubisCO functions in a physiologically significant fashion to fix CO(2). Furthermore, recombinant M. jannaschii, M. acetivorans, and A. fulgidus RubisCO possess unique properties with respect to quaternary structure, temperature optima, and activity in the presence of molecular oxygen compared to the previously described Thermococcus kodakaraensis and halophile proteins.
Collapse
Affiliation(s)
- Michael W Finn
- Department of Microbiology, The Ohio State University, Columbus, Ohio 43210-1292, USA
| | | |
Collapse
|
48
|
Hanson TE, Tabita FR. Insights into the stress response and sulfur metabolism revealed by proteome analysis of a Chlorobium tepidum mutant lacking the Rubisco-like protein. Photosynth Res 2003; 78:231-48. [PMID: 16245053 DOI: 10.1023/b:pres.0000006829.41444.3d] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
A significant fraction of the proteome of Chlorobium tepidum is altered in a mutant strain of the green sulfur bacterium C. tepidum (Omega::RLP) lacking the Rubisco-like protein (RLP). Additionally, a number of stress proteins display altered abundance or migration in strain Omega::RLP, including a thioredoxin, a putative Hsp20 family chaperonin, and GroEL. Changes in protein abundance are closely correlated to mRNA abundance in the case of two other stress proteins, a thiol-specific antioxidant protein homolog (Tsa/AhpC) and an iron only superoxide dismutase (Fe-SOD). Strain Omega::RLP is more resistant to hydrogen peroxide exposure than strain WT2321, providing evidence that the stress proteins are functional. Strain Omega::RLP is also defective in thiosulfate oxidation, but is able to oxidize sulfide as well as the wild-type strain. Based on studies with periplasm-enriched extracts of strain Omega::RLP, the loss of thiosulfate oxidation capability correlates with undetectable levels of the Sox Y protein, a component of the predicted thiosulfate oxidation complex. These results provide further indications that sulfur oxidation capacity and the response to stress are linked in C. tepidum, with the RLP playing a major role.
Collapse
Affiliation(s)
- Thomas E Hanson
- Graduate College of Marine Studies and Delaware Biotechnology Institute, University of Delaware, Newark, DE 19711, USA
| | | |
Collapse
|
49
|
Smith SA, Tabita FR. Up-regulated expression of the cbb(I) and cbb(II) operons during photoheterotrophic growth of a ribulose 1,5-bisphosphate carboxylase-oxygenase deletion mutant of Rhodobacter sphaeroides. J Bacteriol 2002; 184:6721-4. [PMID: 12426361 PMCID: PMC135416 DOI: 10.1128/jb.184.23.6721-6724.2002] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
In a Rhodobacter sphaeroides ribulose 1,5-bisphosphate carboxylase-oxygenase deletion strain that requires an exogenous electron donor for photoheterotrophic growth, transcription of the genes of the Calvin-Benson-Bassham (CBB) cycle was increased. This finding pointed to a potential physiological effector that enhances the capability of the positive transcriptional activator CbbR to mediate cbb transcription. This effector is most likely ribulose 1,5-bisphosphate or a metabolite derived from this CBB pathway intermediate.
Collapse
Affiliation(s)
- Stephanie A Smith
- Department of Microbiology and Plant Molecular Biology and Biotechnology Program, The Ohio State University, Columbus, Ohio 43210-1292, USA
| | | |
Collapse
|
50
|
Gibson JL, Dubbs JM, Tabita FR. Differential expression of the CO2 fixation operons of Rhodobacter sphaeroides by the Prr/Reg two-component system during chemoautotrophic growth. J Bacteriol 2002; 184:6654-64. [PMID: 12426354 PMCID: PMC135422 DOI: 10.1128/jb.184.23.6654-6664.2002] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
In Rhodobacter sphaeroides, the two cbb operons encoding duplicated Calvin-Benson Bassham (CBB) CO2 fixation reductive pentose phosphate cycle structural genes are differentially controlled. In attempts to define the molecular basis for the differential regulation, the effects of mutations in genes encoding a subunit of Cbb3 cytochrome oxidase, ccoP, and a global response regulator, prrA (regA), were characterized with respect to CO2 fixation (cbb) gene expression by using translational lac fusions to the R. sphaeroides cbb(I) and cbb(II) promoters. Inactivation of the ccoP gene resulted in derepression of both promoters during chemoheterotophic growth, where cbb expression is normally repressed; expression was also enhanced over normal levels during phototrophic growth. The prrA mutation effected reduced expression of cbb(I) and cbb(II) promoters during chemoheterotrophic growth, whereas intermediate levels of expression were observed in a double ccoP prrA mutant. PrrA and ccoP1 prrA strains cannot grow phototrophically, so it is impossible to examine cbb expression in these backgrounds under this growth mode. In this study, however, we found that PrrA mutants of R. sphaeroides were capable of chemoautotrophic growth, allowing, for the first time, an opportunity to directly examine the requirement of PrrA for cbb gene expression in vivo under growth conditions where the CBB cycle and CO2 fixation are required. Expression from the cbb(II) promoter was severely reduced in the PrrA mutants during chemoautotrophic growth, whereas cbb(I) expression was either unaffected or enhanced. Mutations in ccoQ had no effect on expression from either promoter. These observations suggest that the Prr signal transduction pathway is not always directly linked to Cbb3 cytochrome oxidase activity, at least with respect to cbb gene expression. In addition, lac fusions containing various lengths of the cbb(I) promoter demonstrated distinct sequences involved in positive regulation during photoautotrophic versus chemoautotrophic growth, suggesting that different regulatory proteins may be involved. In Rhodobacter capsulatus, ribulose 1,5-bisphosphate carboxylase-oxygenase (RubisCO) expression was not affected by cco mutations during photoheterotrophic growth, suggesting that differences exist in signal transduction pathways regulating cbb genes in the related organisms.
Collapse
Affiliation(s)
- Janet L Gibson
- Department of Microbiology and Plant Molecular Biology/Biotechnology Program, The Ohio State University, Columbus, Ohio 43210-1292, USA
| | | | | |
Collapse
|