• Journal of Photoscience
• /
• v.12 no.3
• /
• pp.129-133
• /
• 2005

The psbC gene, encoding the intrinsic chlorophyll-binding protein of CP43, one of the PS core complex polypeptides, was cloned from the Panax ginseng chloroplast, which is composed of 1,422 nucleotides and the overall nucleotide sequence shows more than 84% identity to those of eukaryotic photosynthetic organisms. The predicted topology of CP43, based on hydropathy analysis, includes six membrane-spanning ${\alpha}-helices$ resulting in three lumenal and four stromal loops. The putative translation start codon for the psbC gene is located at 48 nucleotides upstream from the stop codon of the psbD gene whose product is also a component of the PSII reaction center, implying that the promoter of the psbC gene is possibly located in the middle of the structural gene of the psbD gene. Northern blot analysis of the in vivo accumulation of the psbC transcript from the plants grown under the various growth light intensities (5%, 10%, 20%, and 100%) of daylight indicated that the steady-state level of the psbC transcript was not significantly affected by light intensity.

• Bulletin of the Korean Chemical Society
• /
• v.30 no.3
• /
• pp.623-629
• /
• 2009

We have performed replica-exchange molecular dynamics simulations on 41 residue peptide mainly composed of NAC (non A$\beta$ component) sequence in $\alpha$-Synuclein. To investigate conformational characteristics of intrinsically unstructured peptides, we carried out structural analysis on the ‘representative structures’ for ensemble of structures occurring at different temperatures. The secondary structure profile obtained from our simulations suggests that the NAC region of $\alpha$-synuclein can be divided into roughly three helical-like segments. It is found that the overall helix-turn-helix like topology is conserved even though the conformational fluctuations grow as the temperature increases. The coordinate-based and the distance-based representative structures exhibit noticeable differences at higher temperatures while they are similar at lower temperatures. It is found that structural variations for the coordinate-based representative structures are much larger, suggesting that distance-based representative structures provide more reliable information concerning characteristic features of intrinsically unstructured proteins. The present analysis also indicates that the conformational features of representative structures at high temperatures might be related to those in membrane or low pH environment.

• Molecules and Cells
• /
• v.39 no.6
• /
• pp.495-500
• /
• 2016

We have solved the crystal structure of a predicted fructose-specific enzyme $IIB^{fruc}$ from Escherichia coli ($EcEIIB^{fruc}$) involved in the phosphoenolpyruvate-carbohydrate phosphotransferase system transferring carbohydrates across the cytoplasmic membrane. $EcEIIB^{fruc}$ belongs to a sequence family with more than 5,000 sequence homologues with 25-99% amino-acid sequence identity. It reveals a conventional Rossmann-like ${\alpha}-{\beta}-{\alpha}$ sandwich fold with a unique ${\beta}$-sheet topology. Its C-terminus is longer than its closest relatives and forms an additional ${\beta}$-strand whereas the shorter C-terminus is random coil in the relatives. Interestingly, its core structure is similar to that of enzyme $IIB^{cellobiose}$ from E. coli ($EcIIB^{cel}$) transferring a phosphate moiety. In the active site of the closest $EcEIIB^{fruc}$ homologues, a unique motif CXXGXAHT comprising a P-loop like architecture including a histidine residue is found. The conserved cysteine on this loop may be deprotonated to act as a nucleophile similar to that of $EcIIB^{cel}$. The conserved histidine residue is presumed to bind the negatively charged phosphate. Therefore, we propose that the catalytic mechanism of $EcEIIB^{fruc}$ is similar to that of $EcIIB^{cel}$ transferring phosphoryl moiety to a specific carbohydrate.