Hjkhg Essay, Research Paper
ts, and biochemical pathways. In comparing the organism 60% of M. jannaschii’s
coding regions did not correlate with the known sequence database. 40% of the coding regions match the sequences of
bacteria and eukaryotes. Those sequences that are similar to bacteria are genes related to energy production, cell division, and
metabolism, whereas the transcription, translation, and replication gene sequences seem to be more similar to eukaryotes .
*EM/*Methanococcus jannaschii*/EM* consists of three parts: the main circular chromosome, and a large and small circular
extrachromosomal element (ECE).. The chromosome contains 1,664,976 base pairs (G+C content 31.4%), the large ECE,
58,407 bp (G+C content 28.2%), and the small ECE, 16,550 bp (G+C content 28.8%). There are a total of 1738 predicted
coding regions:1682 regions on the chromosome, 44 on the large ECE, and 12 on the small ECE. The function of the ECE’s is
still unknown.
The National Center for Genome Resources has published the complete
genome of M. jannaschii in its publicly available Genome Sequence DataBase
(GSDB). The sequence of the genome is the work of researchers at The
Institute of Genomic Research (TIGR), the University of Illinois, Urbana; and
Johns Hopkins University. The complete M. jannaschii genome is available
only from GSDB. Other databases break large sequences into pieces no
longer than 300 KB. In addition, GSDB allows third-party annotation to M.
jannaschii . This enables researchers other than the original authors of the
sequence to contribute new information to this genome sequence.
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PAN, the proteasome-activating nucleotidase from archaebacteria, is a
protein-unfolding molecular chaperone.
The proteasome-activating nucleotidase (PAN) from Methanococcus jannaschii is a complex of relative
molecular mass 650,000 that is homologous to the ATPases in the eukaryotic 26S proteasome. When mixed with 20S archaeal
proteasomes and ATP, PAN stimulates protein degradation. Here we show
proteins and enhances their refolding. These processes do not require ATP hydrolysis, although ATP binding enhances the
ability of PAN to prevent aggregation. PAN also catalyses the unfolding of the green fluorescent protein with an 11-residue
ssrA extension at its carboxy terminus (GFP11). This unfolding requires ATP hydrolysis, and is linked to GFP11 degradation
when 20S proteasomes are also present. This unfolding activity seems to be essential for ATP-dependent proteolysis, although
PAN may function by itself as a molecular chaperone.
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Pressure effects on the composition and thermal
behavior of lipids from the deep-sea thermophile
Methanococcus jannaschii
SM Kaneshiro and DS Clark
Department of Chemical Engineering, University of California, Berkeley 94720, USA.
The deep-sea archaeon Methanococcus jannaschii was grown at 86 degrees C and under 8, 250, and 500 atm (1 atm =
101.29 kPa) of hyperbaric pressure in a high-pressure, high-temperature bioreactor. The core lipid composition of cultures
grown at 250 or 500 atm, as analyzed by supercritical fluid chromatography, exhibited an increased proportion of macrocyclic
archaeol and corresponding reductions in aracheol and caldarchaeol compared with the 8-atm cultures. Thermal analysis of a
model core-lipid system (23% archaeol, 37% macrocyclic archaeol, and 40% caldarchaeol) using differential scanning
calorimetry revealed no well-defined phase transition in the temperature range of 20 to 120 degrees C. Complementary studies
of spin-labeled samples under 10 and 500 atm in a special high-pressure, high-temperature electron paramagnetic resonance
spectroscopy cell supported the differential scanning calorimetry phase transition data and established that pressure has a
lipid-ordering effect over the full range of M. jannaschii’s growth temperatures. Specifically, pressure shifted the temperature
dependence of lipid fluidity by ca. 10 degrees C/500 atm.
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