Dataset Information

Solution structure and thermal stability of ribosomal protein L30e from hyperthermophilic archaeon Thermococcus celer.

ABSTRACT: To understand the structural basis of thermostability, we have determined the solution structure of a thermophilic ribosomal protein L30e from Thermococcus celer by NMR spectroscopy. The conformational stability of T. celer L30e was measured by guanidine and thermal-induced denaturation, and compared with that obtained for yeast L30e, a mesophilic homolog. The melting temperature of T. celer L30e was 94 degrees C, whereas the yeast protein denatured irreversibly at temperatures >45 degrees C. The two homologous proteins also differ greatly in their stability at 25 degrees C: the free energy of unfolding was 45 kJ/mole for T. celer L30e and 14 kJ/mole for the yeast homolog. The solution structure of T. celer L30e was compared with that of the yeast homolog. Although the two homologous proteins do not differ significantly in their number of hydrogen bonds and the amount of solvent accessible surface area buried with folding, the thermophilic T. celer L30e was found to have more long-range ion pairs, more proline residues in loops, and better helix capping residues in helix-1 and helix-4. A K9A variant of T. celer L30e was created by site-directed mutagenesis to examine the role of electrostatic interactions on protein stability. Although the melting temperatures of the K9A variant is approximately 8 degrees C lower than that of the wild-type L30e, their difference in T(m) is narrowed to approximately 4.2 degrees C at 0.5 M NaCl. This salt-dependency of melting temperatures strongly suggests that electrostatic interactions contribute to the thermostability of T. celer L30e.

SUBMITTER: Wong KB

PROVIDER: S-EPMC2323938 | biostudies-literature | 2003 Jul

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

Solution structure and thermal stability of ribosomal protein L30e from hyperthermophilic archaeon Thermococcus celer.

Wong Kam-Bo KB Lee Chi-Fung CF Chan Siu-Hong SH Leung Tak-Yuen TY Chen Yu Wai YW Bycroft Mark M

Protein science : a publication of the Protein Society 20030701 7

To understand the structural basis of thermostability, we have determined the solution structure of a thermophilic ribosomal protein L30e from Thermococcus celer by NMR spectroscopy. The conformational stability of T. celer L30e was measured by guanidine and thermal-induced denaturation, and compared with that obtained for yeast L30e, a mesophilic homolog. The melting temperature of T. celer L30e was 94 degrees C, whereas the yeast protein denatured irreversibly at temperatures >45 degrees C. Th ...[more]

PMID: 12824494

Similar Datasets

Project description:NAD+ is an important cofactor for enzymatic oxidation reactions in all living organisms, including (hyper)thermophiles. However, NAD+ is susceptible to thermal degradation at high temperatures. It can thus be expected that (hyper)thermophiles harbor mechanisms that maintain in vivo NAD+ concentrations and possibly remove and/or reuse undesirable degradation products of NAD+ Here we confirmed that at 85°C, thermal degradation of NAD+ results mostly in the generation of nicotinamide and ADP-ribose, the latter known to display toxicity by spontaneously linking to proteins. The hyperthermophilic archaeon Thermococcus kodakarensis possesses a putative ADP-ribose pyrophosphatase (ADPR-PPase) encoded by the TK2284 gene. ADPR-PPase hydrolyzes ADP-ribose to ribose 5-phosphate (R5P) and AMP. The purified recombinant TK2284 protein exhibited activity toward ADP-ribose as well as ADP-glucose. Kinetic analyses revealed a much higher catalytic efficiency toward ADP-ribose, suggesting that ADP-ribose was the physiological substrate. To gain insight into the physiological function of TK2284, a TK2284 gene disruption strain was constructed and examined. Incubation of NAD+ in the cell extract of the mutant strain at 85°C resulted in higher ADP-ribose accumulation and lower AMP production compared with those in experiments with the host strain cell extract. The mutant strain also exhibited lower cell yield and specific growth rates in a synthetic amino acid medium compared with those of the host strain. The results obtained here suggest that the ADPR-PPase in T. kodakarensis is responsible for the cleavage of ADP-ribose to R5P and AMP, providing a means to utilize the otherwise dead-end product of NAD+ breakdown.IMPORTANCE Hyperthermophilic microorganisms living under high temperature conditions should have mechanisms that deal with the degradation of thermolabile molecules. NAD+ is an important cofactor for enzymatic oxidation reactions and is susceptible to thermal degradation to ADP-ribose and nicotinamide. Here we show that an ADP-ribose pyrophosphatase homolog from the hyperthermophilic archaeon Thermococcus kodakarensis converts the detrimental ADP-ribose to ribose 5-phosphate and AMP, compounds that can be directed to central carbon metabolism. This physiological role for ADP-ribose pyrophosphatases might be universal in hyperthermophiles, as their homologs are widely distributed among both hyperthermophilic bacteria and archaea.

Project description:Prokaryotes have relatively small genomes, densely-packed with protein-encoding sequences. RNA sequencing has, however, revealed surprisingly complex transcriptomes and here we report the transcripts present in the model hyperthermophilic Archaeon, Thermococcus kodakarensis, under different physiological conditions.Sequencing cDNA libraries, generated from RNA isolated from cells under different growth and metabolic conditions has identified >2,700 sites of transcription initiation, established a genome-wide map of transcripts, and consensus sequences for transcription initiation and post-transcription regulatory elements. The primary transcription start sites (TSS) upstream of 1,254 annotated genes, plus 644 primary TSS and their promoters within genes, are identified. Most mRNAs have a 5'-untranslated region (5'-UTR) 10 to 50 nt long (median = 16 nt), but ~20% have 5'-UTRs from 50 to 300 nt long and ~14% are leaderless. Approximately 50% of mRNAs contain a consensus ribosome binding sequence. The results identify TSS for 1,018 antisense transcripts, most with sequences complementary to either the 5'- or 3'-region of a sense mRNA, and confirm the presence of transcripts from all three CRISPR loci, the RNase P and 7S RNAs, all tRNAs and rRNAs and 69 predicted snoRNAs. Two putative riboswitch RNAs were present in growing but not in stationary phase cells. The procedure used is designed to identify TSS but, assuming that the number of cDNA reads correlates with transcript abundance, the results also provide a semi-quantitative documentation of the differences in T. kodakarensis genome expression under different growth conditions and confirm previous observations of substrate-dependent specific gene expression. Many previously unanticipated small RNAs have been identified, some with relative low GC contents (? 50%) and sequences that do not fold readily into base-paired secondary structures, contrary to the classical expectations for non-coding RNAs in a hyperthermophile.The results identify >2,700 TSS, including almost all of the primary sites of transcription initiation upstream of annotated genes, plus many secondary sites, sites within genes and sites resulting in antisense transcripts. The T.?kodakarensis genome is small (~2.1 Mbp) and tightly packed with protein-encoding genes, but the transcriptomes established also contain many non-coding RNAs and predict extensive RNA-based regulation in this model Archaeon.

Project description:Background: Prokaryotes have relatively small genomes, densely-packed and apparently dominated by protein-encoding sequences. However, data now generated by high throughput RNA sequencing (RNA-seq) reveal surprisingly more-complex transcriptomes with many previously unrecognized and unanticipated non-coding small and antisense transcripts. To date, such studies have investigated primarily Bacteria. Here, we report the transcripts present in Thermococcus kodakarensis, a model hyperthermophilic Archaeon, synthesized under different growth and metabolic conditions. Results: cDNA libraries, generated from RNA preparations isolated from cells growing in media with sulfur or pyruvate, with sulfur to stationary phase, and growing with pyruvate but with sulfur added 20 min before RNA isolation, have been deep-sequenced. The results identify >2,700 sites of transcription initiation, establish a genome-wide map of transcripts, and consensus sequences for transcription initiation and post-transcription regulatory elements in T. kodakarensis. Primary transcription start sites (TSS) are identified upstream of 1,254 annotated genes, including ~78 % of those predicted by promoter locations, and an additional 644 primary TSS and their promoters have been identified within genes. Most of the mRNAs have a 5'-untranslated region (5'-UTR) between 10 and 50 nt long (median length = 16 nt), ~20 % have 5'-UTRs from 50 to 300 nt long, ~14 % are leaderless with 5'-UTRs ≤8 nt, and ~50% contain a consensus ribosome binding sequence. The results also identify TSS for 1,018 antisense transcripts, most with sequences complementary to either the 5'- or 3'-region of a sense mRNA. The data confirm the presence of transcripts from all three CRISPR loci, the RNase P and 7S RNAs, all tRNAs and rRNAs and 69 snoRNAs predicted to be encoded in the T. kodakarensis genome. Two transcripts, putatively identified as riboswitches, were present in RNA preparations isolated from growing but not from stationary phase cells. The procedure used is designed to identify TSS but, assuming that the number of cDNA reads correlates with transcript abundance, the data obtained also provide a semi-quantitative overview of global operon expression. They document substantial differences in gene expression under different physiological conditions and are consistent with previous observations of substrate-dependent specific gene expression. Many previously unrecognized and unanticipated small RNAs have been identified, some with relative low GC contents (≤50%) and sequences that do not fold readily into base-paired secondary structures, contrary to the classical expectations for non-coding RNAs in a hyperthermophile. Conclusion: We have identified >2,700 TSS that include almost all of the primary sites of transcription initiation upstream of annotated genes, and also many secondary sites, sites within genes and sites resulting in antisense transcripts. The T. kodakarensis genome is small (~2.1 Mbp) and tightly packed with protein-encoding genes, but the results reveal the presence of many non-coding RNAs and predict extensive RNA-based regulation in T. kodakarensis.

Dataset Information

Solution structure and thermal stability of ribosomal protein L30e from hyperthermophilic archaeon Thermococcus celer.

Publications

Solution structure and thermal stability of ribosomal protein L30e from hyperthermophilic archaeon Thermococcus celer.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets