1H NMR spectroscopic studies of calcium-binding proteins. 3. Solution conformations of rat apo-alpha-parvalbumin and metal-bound rat alpha-parvalbumin.


Abstract

Lacking the extraordinary thermal stability of its metal-bound forms, apo-alpha-parvalbumin from rat muscle assumes two distinct conformations in aqueous solution. At 25 degrees C, its highly structured form predominates (Keq = 5.7; delta G degree = -4.3 kJ X mol-1); as deduced from both 1H NMR and circular dichroism (CD) spectroscopy, this conformation is exceedingly similar to those of its Mg(II)-, Ca(II)-, and Lu(III)-bound forms. The temperature dependences of several well-resolved aromatic and upfield-shifted methyl 1H NMR resonances and several CD bands indicate that the native, highly helical structure of rat apo-alpha-parvalbumin is unfolded by a concerted mechanism, showing no indication of partially structured intermediates. The melting temperature, TM, of rat apo-alpha-parvalbumin is 35 +/- 0.5 degrees C as calculated by both spectroscopic techniques. By 45 degrees C, rat apo-alpha-parvalbumin unfolds entirely, losing the tertiary structure that characterizes its folded form: not only are the ring-current-shifted aromatic and methyl 1H NMR resonances leveled, but the 262- and 269-nm CD bands are also severely reduced. As judged by the decrease in the negative ellipticity of the 222-nm CD band, this less-structured form of rat apo-alpha-parvalbumin shows an approximate 50% loss in apparent alpha-helical content compared to its folded state. Several changes in the 1H NMR spectrum of rat apo-alpha-parvalbumin were exceptionally informative probes of the specific conformational changes that accompany metal ion binding and metal ion exchange. In particular, the line intensities of the ortho proton resonance of Phe-47, the unassigned downfield-shifted alpha-CH resonances from the beta-sheet contacts between the metal-binding loops, the C2H resonance of His-48, and the epsilon-CH3 resonance of an unassigned Met residue were monitored as a function of added metal to determine the stability constants of several metal ion-parvalbumin complexes. We conclude that Mg(II) binds to the CD and EF sites independently, its affinity for the EF site being almost twice that for the CD site. Mg(II)----Ca(II) exchange showed that the CD-site Mg(II) is displaced first, in contrast to Lu(III)'s preferential displacement of the EF-site Ca(II) as determined from the Ca(II)----Lu(III) exchange experiments.(ABSTRACT TRUNCATED AT 400 WORDS) Study holds ProTherm entries: 3973 Extra Details: helical structure; conformational changes; metal ion binding;,stability constants; charge-charge repulsions

Submission Details

ID: 38DgWA463

Submitter: Connie Wang

Submission Date: April 24, 2018, 8:23 p.m.

Version: 1

Publication Details
Williams TC;Corson DC;Oikawa K;McCubbin WD;Kay CM;Sykes BD,Biochemistry (1986) 1H NMR spectroscopic studies of calcium-binding proteins. 3. Solution conformations of rat apo-alpha-parvalbumin and metal-bound rat alpha-parvalbumin. PMID:3707914
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
1RJV 2004-05-25 Solution Structure of Human alpha-Parvalbumin refined with a paramagnetism-based strategy
1RK9 2004-06-08 Solution Structure of Human alpha-Parvalbumin (Minimized Average Structure)
2JWW 2008-08-12 Calcium-free rat alpha-parvalbumin
2NLN 2007-09-11 Solution Structure of Calcium-free Rat Beta-parvalbumin
1RWY 2004-05-11 1.05 CRYSTAL STRUCTURE OF RAT ALPHA-PARVALBUMIN AT 1.05 RESOLUTION
1RRO 1993-10-31 1.3 REFINEMENT OF RECOMBINANT ONCOMODULIN AT 1.30 ANGSTROMS RESOLUTION
1G33 2001-10-03 1.44 CRYSTAL STRUCTURE OF RAT PARVALBUMIN WITHOUT THE N-TERMINAL DOMAIN
1XVJ 2005-09-20 1.8 Crystal Structure Of Rat alpha-Parvalbumin D94S/G98E Mutant
1OMD 1991-07-15 1.85 STRUCTURE OF ONCOMODULIN REFINED AT 1.85 ANGSTROMS RESOLUTION. AN EXAMPLE OF EXTENSIVE MOLECULAR AGGREGATION VIA CA2+
3F45 2009-07-07 2.0 Structure of the R75A mutant of rat alpha-Parvalbumin
1RTP 1994-01-31 2.0 REFINED X-RAY STRUCTURE OF RAT PARVALBUMIN, A MAMMALIAN ALPHA-LINEAGE PARVALBUMIN, AT 2.0 A RESOLUTION
1S3P 2004-09-07 2.0 Crystal structure of rat alpha-parvalbumin S55D/E59D mutant

Relevant UniProtKB Entries

Percent Identity Matching Chains Protein Accession Entry Name
91.8 Parvalbumin alpha P20472 PRVA_HUMAN
93.6 Parvalbumin alpha P80050 PRVA_MACFU
94.5 Parvalbumin alpha P80080 PRVA_GERSP
94.5 Parvalbumin alpha P32848 PRVA_MOUSE
100.0 Parvalbumin alpha P02625 PRVA_RAT
91.7 Oncomodulin O35508 ONCO_CAVPO
95.4 Oncomodulin P51879 ONCO_MOUSE
100.0 Oncomodulin P02631 ONCO_RAT