A Model of the Quaternary Structure of Enolases, Based on Structural and Evolutionary Analysis of the Octameric Enolase from Bacillus subtilis
| Autor: | Brown Ck, Calie Pj, Slates K, William W. Farrar, Mattingly S, Kuhlman Pl |
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| Rok vydání: | 1998 |
| Předmět: |
Models
Molecular Protein Conformation Protein subunit Molecular Sequence Data Enolase Bacillus subtilis Glyceric Acids Biochemistry Evolution Molecular Fungal Proteins Bacterial Proteins Tetramer Amino Acid Sequence Histone octamer Sequence Homology Amino Acid biology Hydrogen-Ion Concentration biology.organism_classification Molecular Weight Kinetics Phosphopyruvate Hydratase Thermotoga maritima Helix Protein quaternary structure Isoelectric Focusing Dimerization |
| Zdroj: | Journal of Protein Chemistry. 17:855-866 |
| ISSN: | 1573-4943 0277-8033 |
| DOI: | 10.1023/a:1020790604887 |
| Popis: | Purified enolase from Bacillus subtilis has a native mass of approximately 370 kDa. Since B. subtilis enolase was found to have a subunit mass of 46.58 kDa, the quaternary structure of B. subtilis is octameric. The pl for B. subtilis enolase is 6.1, the pH optimum (pHo) for activity is 8.1-8.2, and the Km for 2-PGA is approximately 0.67 mM. Using the dimeric Calpha structure of yeast dimeric enolase as a guide, these dimers were arranged as a tetramer of dimers to simulate the electron microscopy image processing obtained for the octameric enolase purified from Thermotoga maritima. This arrangement allowed identification of helix J of one dimer (residues 86-96) and the loop between helix L and strand 1 (HL-S1 loop) of another dimer as possible subunit interaction regions. Alignment of available enolase amino acid sequences revealed that in 16 there are two tandem glycines at the C-terminal end of helix L and the HL-S1 loop is truncated by 4-6 residues relative to the yeast polypeptide, two structural features absent in enolases known to be dimers. From these arrangements and alignments it is proposed that the GG tandem at the C-terminal end of helix L and truncation of the HL-S1 loop may play a critical role in octamer formation of enolases. Interestingly, the sequence features associated with dimeric quaternary structure are found in three phylogenetically disparate groups, suggesting that the ancestral enolase was an octamer and that the dimeric structure has arisen independently multiple times through evolutionary history. |
| Databáze: | OpenAIRE |
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