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 that PAN reduces aggregation of denatured

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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