PP01

Effects Of Glycosylation And Phosphorylation On The Conformational Energy Of The Prion Peptide And The Formation Of Amyloid Fibril

Chai-Chi Ho1, Chun-Cheng Lin2, and Rita P.-Y. Chen1

1 Institute of Biological Chemistry, Academia Sinica2 Institute of Chemistry, Academia Sinica

 

Prion disease is a neurodegenerative disorder.  The prion formation, resulting from a structural conversion of the prion protein from the cellular form (Prpc) to the pathogenic isoform (PrpSc), is the culprit of the malady.  A posttranslational process on the prion protein has been implicated in the prion formation during the development of prion disease.  However, what the modification is and how the modification works remain elusive.  It has been found that adding one single sugar on the prion peptide (sequence 108-144) can affect the structural conversion of the modified peptide and the following amyloid fibril formation.  Interestingly, this effect is sugar-specific.   Introducing an aa-GalNAc to Ser-135 of the prion peptide could suppress the fibrillization while adding a bb-GlcNAc did not yield the same effect.  In order to understand the origin of the effect, we performed a series glycosylations with these two sugars and another two non-native isomers bb-GalNAc, and aa-GlcNAc and compared their effects on the fibrillization of the prion peptide.  We found that the anomeric position is the origin of the inhibition.  Either aa-GalNAc or aa-GlcNAc has more prominent influence on the conformational energy of the peptide and inhibits the assembly of the peptide to form amyloid. The glycosylation and phosphorylation are also compared.

 

 

PP02

Structural basis of a flavivirus recognized by its neutralizing antibody:

solution structure of the domain III of the Japanese encephalitis virus envelope protein.

 

Jya-Wei Cheng, Kuen-Phon Wu, Chih-Wei Wu, Ya-Ping Tsao, Ting-Wei Kuo, Yuan-Chao Lou,

Cheng-Wen Lin, and Suh-Chin Wu

Institute of Biotechnology and Department of Life Science,

National Tsing Hua University, Hsinchu, 300, Taiwan.

 

 

The Proteolytic Analysis of the pMOB subunit from the Particulate Methano Monooxygenase (pMMO) Mehanotrophic bacteria use methane as their feedstock and energy source. Particulate methane monooxygenase (pMMO), one of the membrane proteins converting methane to methanol, are enormous expressed (90% in membrane proteins) in these bacteria under high copper concentrations. pMMO contains three subunits: a-, b-, g-subunits.  Those subunits have been characterized through N-terminal sequence method and identified as 27 kDa, 45 kDa and 23 kDa, respectively. pMMO is less well studied than sMMO (soluble methane monooxyenase) due to the difficulty to obtain the well-resolved optical spectroscopic data in the presence of the membranes as well as the instability upon removal of the proteins from the membrane lipids. To overcome this circumstance, we, herein, developed a method to resolve the structural in formation directly when the proteins are still associated with the membrane. Proteins enriched membranes are easy to be separated from the soluble proteins through high-speed ultra-centrifugation operation.  Due to the hydrophobicity of the oil layer of the cell membrane, trypsin (cleavage site occurred at Lys and Arg) would be difficult to digest the membrane domains whereas the peptides located at the cytosolic exposed domains would be observed in the supernatants and could be characterized through the mass spectroscopic methods.  The appearances of the peptides fragments were studies will facilitate the insight of structural information regarding to the cytoplasmic domains and transmembrane domains.  To understand the three-dimensional fold and orientation of the secondary structure will provide us the detail about functional mechanism of the membrane proteins.

  

 

PP03

Deciphering the Protein Network of Caenorhabditis elegans in

the Approach of Systems Biology

Chia-Ming Chang, Chia-Ling Chen, Chung-Yen Lin, Chi-Shiang Cho, Li-Ming Wang, Pao-Yang Chen,

Chen-Zen Lo and, Chao A. Hsiung

Division of Biostatistics and Bioinformatics, National Health Research Institutes

128, Sec. 2 Yaun-Chio-Yun Rd. Taipei 115, Taiwan

 

Proteins control and mediate many of the biological activities of cells through interacting with protein partners. In order to understand how cell functions and the consequent phenotype exerted as a result, protein networking information derived from protein interactions therefore, acting as blueprint of cell mechanism. Caenorhabditis elegans is a small, free-living bacteriovorous soil nematode studied for more than 40 years as model organism with at least rudiments of the physiological systems - feeding, nervous, muscle, reproductive - found in "higher" animals like mice and humans. Our goal here is to contribute on studies related to C. elegans from view of systemic proteomics through protein interaction networks. Database of Protein Interactomes for C. elegans (Ce-DPI) incorporates C. elegans protein interactions from a recent study of two-hybrid analysis and inferring interactions derived from these experimental data with computed estimates of domains association measure resulting in an probability matrix, which, on the other hand, are employed to validate the quality of two-hybrid assays by disclosing false positives. To present the enormous amount of protein interactions in a way of protein networking maps, we provide a succinct yet comprehensive visualization tool with detailed annotation information from Genbank, GO, and KEGG, even spatiotemporal information. With Ce-DPI, we successfully identified putative interactions from C. elegans matrix and reconstruct the network to provide a way to decipher the secret of life.