Local and long-range interactions in the molten globule state: A study of chimeric proteins of bovine and human alpha-lactalbumin.


Abstract

The molten globule state of alpha-lactalbumin has ordered secondary structure in the alpha-domain, which comprises residues 1 to 34 and 86 to 123. In order to investigate which part of a polypeptide is important for stabilizing the molten globule state of alpha-lactalbumin, we have produced and studied three chimeric proteins of bovine and human alpha-lactalbumin. The stability of the molten globule state formed by domain-exchanged alpha-lactalbumin, in which the amino acid sequence in the alpha-domain comes from human alpha-lactalbumin and that in the beta-domain comes from bovine alpha-lactalbumin, is the same as that of human alpha-lactalbumin and is substantially greater than that of bovine alpha-lactalbumin. Therefore, our results show that the stability of the molten globule state of alpha-lactalbumin is determined by the alpha-domain and the beta-domain is not important for stabilizing the molten globule state. The substitution of residues 1 to 34 of bovine alpha-lactalbumin with those of human alpha-lactalbumin substantially increases the stability of the molten globule state, while the substitution of residues 86 to 123 of bovine alpha-lactalbumin with those of human alpha-lactalbumin decreases the stability of the molten globule state. Therefore, residues 1 to 34 in human alpha-lactalbumin is more important for the stability of the human alpha-lactalbumin molten globule state than residues 86 to 123. The stabilization of the molten globule state due to substitution of both residues 1 to 34 and 86 to 123 is not identical with the sum of the two individual substitutions, demonstrating the non-additivity of the stabilization of the molten globule state. This result indicates that there is a long-range interaction between residues 1 to 34 and 86 to 123 in the molten globule state of human alpha-lactalbumin. The differences in the stabilities of the molten globule states are well correlated with the averaged helical propensity values in the alpha-domain when the long-range interactions are negligible, suggesting that the local interaction is the dominant term for determining the stability of the molten globule state. Our results also indicate that the apparent cooperativity is closely linked to the stability of the molten globule state, even if the molten globule state is weakly cooperative. Study holds ProTherm entries: 8634, 8635 Extra Details: molten globule to unfolding chimera; alpha-lactalbumin; molten globule; protein folding;,cooperativity

Submission Details

ID: i9akQmsN

Submitter: Connie Wang

Submission Date: April 24, 2018, 8:36 p.m.

Version: 1

Publication Details
Mizuguchi M;Masaki K;Demura M;Nitta K,J. Mol. Biol. (2000) Local and long-range interactions in the molten globule state: A study of chimeric proteins of bovine and human alpha-lactalbumin. PMID:10801363
Additional Information

Structure view and single mutant data analysis

Study data

No weblogo for data of varying length.
Colors: D E R H K S T N Q A V I L M F Y W C G P
 

Data Distribution

Studies with similar sequences (approximate matches)

Correlation with other assays (exact sequence matches)


Relevant PDB Entries

Structure ID Release Date Resolution Structure Title
1ALC 1989-08-14T00:00:00+0000 1.7 REFINED STRUCTURE OF BABOON ALPHA-LACTALBUMIN AT 1.7 ANGSTROMS RESOLUTION. COMPARISON WITH C-TYPE LYSOZYME
1F6R 2000-06-23T00:00:00+0000 2.2 CRYSTAL STRUCTURE OF APO-BOVINE ALPHA-LACTALBUMIN
1F6S 2000-06-23T00:00:00+0000 2.2 CRYSTAL STRUCTURE OF BOVINE ALPHA-LACTALBUMIN
1FKQ 2000-08-10T00:00:00+0000 1.8 RECOMBINANT GOAT ALPHA-LACTALBUMIN T29V
1FKV 2000-08-10T00:00:00+0000 2.0 RECOMBINANT GOAT ALPHA-LACTALBUMIN T29I
1HFY 1996-06-13T00:00:00+0000 2.3 ALPHA-LACTALBUMIN
1HFZ 1996-06-13T00:00:00+0000 2.3 ALPHA-LACTALBUMIN
1HMK 1998-11-26T00:00:00+0000 2.0 RECOMBINANT GOAT ALPHA-LACTALBUMIN
2G4N 2006-02-22T00:00:00+0000 2.3 Anomalous substructure of alpha-lactalbumin
3B0K 2011-06-10T00:00:00+0000 1.6 Crystal structure of alpha-lactalbumin

Relevant UniProtKB Entries

Percent Identity Matching Chains Protein Accession Entry Name
95.1 Alpha-lactalbumin P00712 LALBA_CAPHI
97.2 Alpha-lactalbumin P09462 LALBA_SHEEP
98.6 Alpha-lactalbumin Q9TSN6 LALBA_BUBBU
99.3 Alpha-lactalbumin Q9TSR4 LALBA_BOSMU
100.0 Alpha-lactalbumin P00711 LALBA_BOVIN
91.7 Alpha-lactalbumin P37154 LALBA_FELCA
94.3 Alpha-lactalbumin P12065 LALBA_PAPCY
100.0 Alpha-lactalbumin P00709 LALBA_HUMAN