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Abstract
Identification of operons in the hyperthermophilic archaeon Pyrococcus furiosus represents an important step to understanding the regulatory mechanisms that enable the organism to adapt and thrive in extreme environments. We have predicted operons in P.furiosus by combining the results from three existing algorithms using a neural network (NN). These algorithms use intergenic distances, phylogenetic profiles, functional categories and gene-order conservation in their operon prediction. Our method takes as inputs the confidence scores of the three programs, and outputs a prediction of whether adjacent genes on the same strand belong to the same operon. In addition, we have applied Gene Ontology (GO) and KEGG pathway information to improve the accuracy of our algorithm. The parameters of this NN predictor are trained on a subset of all experimentally verified operon gene pairs of Bacillus subtilis. It subsequently achieved 86.5% prediction accuracy when applied to a subset of gene pairs for Escherichia coli, which is substantially better than any of the three prediction programs. Using this new algorithm, we predicted 470 operons in the P.furiosus genome. Of these, 349 were validated using DNA microarray data.
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Affiliation(s)
| | - Phuongan Dam
- Department of Biochemistry and Molecular Biology, Institute of BioinformaticsUniversity of Georgia, Athens, GA 30602, USA
| | - Zhengchang Su
- Department of Biochemistry and Molecular Biology, Institute of BioinformaticsUniversity of Georgia, Athens, GA 30602, USA
| | - Farris L. Poole
- Department of Biochemistry and Molecular Biology, Institute of BioinformaticsUniversity of Georgia, Athens, GA 30602, USA
| | - Michael W. W. Adams
- Department of Biochemistry and Molecular Biology, Institute of BioinformaticsUniversity of Georgia, Athens, GA 30602, USA
| | | | - Ying Xu
- Department of Biochemistry and Molecular Biology, Institute of BioinformaticsUniversity of Georgia, Athens, GA 30602, USA
- To whom correspondence should be addressed. Tel: +1 706 542 9779; Fax: +1 706 542 9751;
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Bakermans C, Tollaksen SL, Giometti CS, Wilkerson C, Tiedje JM, Thomashow MF. Proteomic analysis of Psychrobacter cryohalolentis K5 during growth at subzero temperatures. Extremophiles 2006; 11:343-54. [PMID: 17123128 DOI: 10.1007/s00792-006-0042-1] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2006] [Accepted: 10/22/2006] [Indexed: 10/23/2022]
Abstract
It is crucial to examine the physiological processes of psychrophiles at temperatures below 4 degrees C, particularly to facilitate extrapolation of laboratory results to in situ activity. Using two dimensional electrophoresis, we examined patterns of protein abundance during growth at 16, 4, and -4 degrees C of the eurypsychrophile Psychrobacter cryohalolentis K5 and report the first identification of cold inducible proteins (CIPs) present during growth at subzero temperatures. Growth temperature substantially reprogrammed the proteome; the relative abundance of 303 of the 618 protein spots detected (approximately 31% of the proteins at each growth temperature) varied significantly with temperature. Five CIPs were detected specifically at -4 degrees C; their identities (AtpF, EF-Ts, TolC, Pcryo_1988, and FecA) suggested specific stress on energy production, protein synthesis, and transport during growth at subzero temperatures. The need for continual relief of low-temperature stress on these cellular processes was confirmed via identification of 22 additional CIPs whose abundance increased during growth at -4 degrees C (relative to higher temperatures). Our data suggested that iron may be limiting during growth at subzero temperatures and that a cold-adapted allele was employed at -4 degrees C for transport of iron. In summary, these data suggest that low-temperature stresses continue to intensify as growth temperatures decrease to -4 degrees C.
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Affiliation(s)
- Corien Bakermans
- Center for Microbial Ecology, Michigan State University, East Lansing, MI 48824, USA.
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Bevers LE, Hagedoorn PL, Krijger GC, Hagen WR. Tungsten transport protein A (WtpA) in Pyrococcus furiosus: the first member of a new class of tungstate and molybdate transporters. J Bacteriol 2006; 188:6498-505. [PMID: 16952940 PMCID: PMC1595483 DOI: 10.1128/jb.00548-06] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
A novel tungstate and molybdate binding protein has been discovered from the hyperthermophilic archaeon Pyrococcus furiosus. This tungstate transport protein A (WtpA) is part of a new ABC transporter system selective for tungstate and molybdate. WtpA has very low sequence similarity with the earlier-characterized transport proteins ModA for molybdate and TupA for tungstate. Its structural gene is present in the genome of numerous archaea and some bacteria. The identification of this new tungstate and molybdate binding protein clarifies the mechanism of tungstate and molybdate transport in organisms that lack the known uptake systems associated with the ModA and TupA proteins, like many archaea. The periplasmic protein of this ABC transporter, WtpA (PF0080), was cloned and expressed in Escherichia coli. Using isothermal titration calorimetry, WtpA was observed to bind tungstate (dissociation constant [K(D)] of 17 +/- 7 pM) and molybdate (K(D) of 11 +/- 5 nM) with a stoichiometry of 1.0 mol oxoanion per mole of protein. These low K(D) values indicate that WtpA has a higher affinity for tungstate than do ModA and TupA and an affinity for molybdate similar to that of ModA. A displacement titration of molybdate-saturated WtpA with tungstate showed that the tungstate effectively replaced the molybdate in the binding site of the protein.
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Affiliation(s)
- Loes E Bevers
- Department of Biotechnology, Delft University of Technology, Julianalaan 67, 2628 BC Delft, The Netherlands
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54
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van de Werken HJG, Verhees CH, Akerboom J, de Vos WM, van der Oost J. Identification of a glycolytic regulon in the archaeaPyrococcusandThermococcus. FEMS Microbiol Lett 2006; 260:69-76. [PMID: 16790020 DOI: 10.1111/j.1574-6968.2006.00292.x] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
The glycolytic pathway of the hyperthermophilic archaea that belong to the order Thermococcales (Pyrococcus, Thermococcus and Palaeococcus) differs significantly from the canonical Embden-Meyerhof pathway in bacteria and eukarya. This archaeal glycolysis variant consists of several novel enzymes, some of which catalyze unique conversions. Moreover, the enzymes appear not to be regulated allosterically, but rather at transcriptional level. To elucidate details of the gene expression control, the transcription initiation sites of the glycolytic genes in Pyrococcus furiosus have been mapped by primer extension analysis and the obtained promoter sequences have been compared with upstream regions of non-glycolytic genes. Apart from consensus sequences for the general transcription factors (TATA-box and BRE) this analysis revealed the presence of a potential transcription factor binding site (TATCAC-N(5)-GTGATA) in glycolytic and starch utilizing promoters of P. furiosus and several thermococcal species. The absence of this inverted repeat in Pyrococcus abyssi and Pyrococcus horikoshii probably reflects that their reduced catabolic capacity does not require this regulatory system. Moreover, this phyletic pattern revealed a TrmB-like regulator (PF0124 and TK1769) which may be involved in recognizing the repeat. This Thermococcales glycolytic regulon, with more than 20 genes, is the largest regulon that has yet been described for Archaea.
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Abstract
Many archaea are extremophiles. They thrive at high temperatures, at high pressure and in concentrated acidic environments. Nevertheless, the largest proportion and greatest diversity of archaea exist in cold environments. Most of the Earth's biosphere is cold, and archaea represent a significant fraction of the biomass. Although psychrophilic archaea have long been the neglected majority, the study of these microorganisms is beginning to come of age. This review casts a spotlight on the ecology, adaptation biology and unique science that is being realized from studies on cold-adapted archaea.
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Affiliation(s)
- Ricardo Cavicchioli
- School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney NSW 2052, Australia.
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van der Oost J, Walther J, Brouns SJJ, van de Werken HJG, Snijders APL, Wright PC, Andersson A, Bernander R, de Vos WM. 9 Functional Genomics of the Thermo-Acidophilic Archaeon Sulfolobus solfataricus. METHODS IN MICROBIOLOGY 2006. [DOI: 10.1016/s0580-9517(08)70012-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Poole FL, Gerwe BA, Hopkins RC, Schut GJ, Weinberg MV, Jenney FE, Adams MWW. Defining genes in the genome of the hyperthermophilic archaeon Pyrococcus furiosus: implications for all microbial genomes. J Bacteriol 2005; 187:7325-32. [PMID: 16237015 PMCID: PMC1272981 DOI: 10.1128/jb.187.21.7325-7332.2005] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The original genome annotation of the hyperthermophilic archaeon Pyrococcus furiosus contained 2,065 open reading frames (ORFs). The genome was subsequently automatically annotated in two public databases by the Institute for Genomic Research (TIGR) and the National Center for Biotechnology Information (NCBI). Remarkably, more than 500 of the originally annotated ORFs differ in size in the two databases, many very significantly. For example, more than 170 of the predicted proteins differ at their N termini by more than 25 amino acids. Similar discrepancies were observed in the TIGR and NCBI databases with the other archaeal and bacterial genomes examined. In addition, the two databases contain 60 (NCBI) and 221 (TIGR) ORFs not present in the original annotation of P. furiosus. In the present study we have experimentally assessed the validity of 88 previously unannotated ORFs. Transcriptional analyses showed that 11 of 61 ORFs examined were expressed in P. furiosus when grown at either 95 or 72 degrees C. In addition, 7 of 54 ORFs examined yielded heat-stable recombinant proteins when they were expressed in Escherichia coli, although only one of the seven ORFs was expressed in P. furiosus under the growth conditions tested. It is concluded that the P. furiosus genome contains at least 17 ORFs not previously recognized in the original annotation. This study serves to highlight the discrepancies in the public databases and the problems of accurately defining the number and sizes of ORFs within any microbial genome.
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Affiliation(s)
- Farris L Poole
- Department of Biochemistry and Molecular Biol., Davison Life Sciences Complex, University of Georgia, Athens, GA 30602-7229, USA
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Bevers LE, Bol E, Hagedoorn PL, Hagen WR. WOR5, a novel tungsten-containing aldehyde oxidoreductase from Pyrococcus furiosus with a broad substrate Specificity. J Bacteriol 2005; 187:7056-61. [PMID: 16199576 PMCID: PMC1251609 DOI: 10.1128/jb.187.20.7056-7061.2005] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
WOR5 is the fifth and last member of the family of tungsten-containing oxidoreductases purified from the hyperthermophilic archaeon Pyrococcus furiosus. It is a homodimeric protein (subunit, 65 kDa) that contains one [4Fe-4S] cluster and one tungstobispterin cofactor per subunit. It has a broad substrate specificity with a high affinity for several substituted and nonsubstituted aliphatic and aromatic aldehydes with various chain lengths. The highest catalytic efficiency of WOR5 is found for the oxidation of hexanal (V(max) = 15.6 U/mg, K(m) = 0.18 mM at 60 degrees C). Hexanal-incubated enzyme exhibits S = 1/2 electron paramagnetic resonance signals from [4Fe-4S]1+ (g values of 2.08, 1.93, and 1.87) and W5+ (g values of 1.977, 1.906, and 1.855). Cyclic voltammetry of ferredoxin and WOR5 on an activated glassy carbon electrode shows a catalytic wave upon addition of hexanal, suggesting that ferredoxin can be a physiological redox partner. The combination of WOR5, formaldehyde oxidoreductase, and aldehyde oxidoreductase forms an efficient catalyst for the oxidation of a broad range of aldehydes in P. furiosus.
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Affiliation(s)
- Loes E Bevers
- Department of Biotechnology, Delft University of Technology, Julianalaan 67, 2628 BC Delft, The Netherlands
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Abstract
One of the first hurdles to be negotiated in the postgenomic era involves the description of the entire protein content of the cell, the proteome. Such efforts are presently complicated by the various posttranslational modifications that proteins can experience, including glycosylation, lipid attachment, phosphorylation, methylation, disulfide bond formation, and proteolytic cleavage. Whereas these and other posttranslational protein modifications have been well characterized in Eucarya and Bacteria, posttranslational modification in Archaea has received far less attention. Although archaeal proteins can undergo posttranslational modifications reminiscent of what their eucaryal and bacterial counterparts experience, examination of archaeal posttranslational modification often reveals aspects not previously observed in the other two domains of life. In some cases, posttranslational modification allows a protein to survive the extreme conditions often encountered by Archaea. The various posttranslational modifications experienced by archaeal proteins, the molecular steps leading to these modifications, and the role played by posttranslational modification in Archaea form the focus of this review.
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Affiliation(s)
- Jerry Eichler
- Dept. of Life Sciences, Ben Gurion University, P.O. Box 653, Beersheva 84105, Israel.
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