Solution Structure of Carnobacteriocin B2 and Implications for Structure−Activity Relationships among Type IIa Bacteriocins from Lactic Acid Bacteria
| Autor: | Liang Z. Yan, John C. Vederas, David S. Wishart, Yunjun Wang, Matthias E. Henz, Michael E. Stiles, Nancy L. Fregeau Gallagher, Shengyong Chai, Alan C. Gibbs |
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| Rok vydání: | 1999 |
| Předmět: |
Models
Molecular Protein Conformation Stereochemistry Molecular Sequence Data Carboxylic Acids Peptide Carnobacterium Crystallography X-Ray Gram-Positive Bacteria Methylation Biochemistry Protein Structure Secondary Structure-Activity Relationship Residue (chemistry) chemistry.chemical_compound Bacterial Proteins Bacteriocins Bacteriocin Amino Acid Sequence Lactic Acid Nuclear Magnetic Resonance Biomolecular chemistry.chemical_classification Sequence Homology Amino Acid biology Chemistry biology.organism_classification Solution structure Lactic acid Solutions Thiol Oxidation-Reduction Leuconostoc Bacteria |
| Zdroj: | Biochemistry. 38:15438-15447 |
| ISSN: | 1520-4995 0006-2960 |
| DOI: | 10.1021/bi991351x |
| Popis: | Carnobacteriocin B2 (CbnB2), a type IIa bacteriocin, is a 48 residue antimicrobial peptide from the lactic acid bacterium Carnobacterium pisicola LV17B. Type IIa bacteriocins have a conserved YGNGVXC sequence near the N-terminus and usually contain a disulfide bridge. CbnB2 seemed to be unique in that its two cysteines (Cys9 and Cys14) could be isolated as free thiols [Quadri et al. (1994) J. Biol. Chem. 26, 12204-12211]. To establish the structural consequences of the presence or absence of a disulfide bridge and to investigate if the YGNGVXC sequence is a receptor-binding motif [Fleury et al. (1996) J. Biol. Chem. 271, 14421-14429], the three-dimensional solution structure of CbnB2 was determined by two-dimensional (1)H nuclear magnetic resonance (NMR) techniques. Mass spectroscopic and thiol modification experiments on CbnB2 and on model peptides, in conjunction with activity measurements, were used to verify the redox status of CbnB2. The results show that CbnB2 readily forms a disulfide bond and that this peptide has full antimicrobial activity. NMR results indicate that CbnB2 in trifluoroethanol (TFE) has a well-defined central helical structure (residues 18-39) but a disordered N terminus. Comparison of the CbnB2 structure with the refined solution structure of leucocin A (LeuA), another type IIa bacteriocin, indicates that the central helical structure is conserved between the two peptides despite differences in sequence but that the N-terminal structure (a proposed receptor binding site) is not. This is unexpected because LeuA and CbnB2 exhibit66% sequence identity in the first 24 residues. This suggests that the N-terminus, which had been proposed [Fleury et al. (1996) J. Biol. Chem. 271, 14421-14429] to be a receptor binding site of type IIa bacteriocins, may not be directly involved and that recognition of the amphiphilic helical portion is the critical feature. |
| Databáze: | OpenAIRE |
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