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Differences in the structural stability and cooperativity between monomeric variants of natural and <i>de novo</i> Cro proteins revealed by high pressure FTIR spectroscopy.
MedLine Citation:
PMID:  22482462     Owner:  NLM     Status:  Publisher    
Abstract/OtherAbstract:
It is widely accepted that pressure affects the structure and dynamics of proteins; however, the underlying mechanism remains unresolved. Our previous studies have investigated pressure effects on fundamental secondary structural elements using model peptides, because these peptides represent a basis from which to understand pressure effects on more complex structures. The present study targeted monomeric variants of naturally occurring bacteriophage λ Cro (natural Cro) and de novo designed λ Cro (SN4m), which are α + β proteins. The sequence of SN4m is 75% different from natural Cro, but the structures are almost identical. Consequently, a comparison of the folding properties of these proteins is of interest. Pressure- and temperature-variable FTIR spectroscopic analyses revealed that the α-helices and the β-sheets of natural Cro are cooperatively and reversibly unfolded by pressure and temperature, whereas those of SN4m are not cooperatively unfolded by pressure, i.e., the α-helices of SN4m unfold at significantly higher pressure than the β-sheets, and irreversibly unfold by temperature. The higher unfolding pressure for the α-helices of SN4m indicates the presence of an intermediate structure of SN4m that does not retain β-sheet structure but does preserve the α-helices. The present results demonstrate that the α-helices of natural Cro are stabilized by global tertiary contacts among the α-helices and the β-sheets, whereas the α-helices of SN4m are stabilized by local tertiary contacts between the α-helices.
Authors:
Hiroshi Imamura; Yasuhiro Isogai; Minoru Kato
Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2012-4-6
Journal Detail:
Title:  Biochemistry     Volume:  -     ISSN:  1520-4995     ISO Abbreviation:  -     Publication Date:  2012 Apr 
Date Detail:
Created Date:  2012-4-9     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  0370623     Medline TA:  Biochemistry     Country:  -    
Other Details:
Languages:  ENG     Pagination:  -     Citation Subset:  -    
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