Acid-induced changes in thermal stability and fusion activity of influenza hemagglutinin.


The conformational and thermal stability of full-length hemagglutinin (HA) of influenza virus (strain X31) has been investigated using a combination of differential scanning calorimetry (DSC), analytical ultracentrifugation, fluorescence, and circular dichroism (CD) spectroscopy as a function of pH. HA sediments as a rosette comprised of 5-6 trimers (31-35 S) over the pH range of 7.4-5.4. The DSC profile of HA in the native state at pH 7.4 is characterized by a single cooperative endotherm with a transition temperature (Tm) of 66 degrees C and unfolding enthalpy (DeltaH(cal)) of 800 kcal x (mol of trimer)(-1). Upon acidification to pH 5.4, there is a significant decrease in the transition temperature (from 66 to 45 degrees C), unfolding enthalpy [from 800 to 260 kcal x (mol of trimer)(-1)], and DeltaH(cal)/DeltaH(vH) ratio (from 3.0 to approximately 1.3). Whereas the far- and near-UV ellipticities are maintained over this pH range, there is an acid-induced increase in surface hydrophobicity and decrease in intrinsic tryptophanyl fluorescence. The major contribution to the DSC endotherm arises from unfolding HA1 domains. The relationship between acid-induced changes in thermal stability and the fusion activity of HA has been examined by evaluating the kinetics and extent of fusion of influenza virus with erythrocytes over the temperature and pH range of the DSC measurements. Surprisingly, X31 influenza virus retains its fusion activity at acidic pH and temperatures significantly below the unfolding transition of HA. This finding is consistent with the notion that the fusion activity of influenza virus may involve structural changes of only a small fraction of HA molecules. Study holds ProTherm entries: 13017, 13018, 13019, 13020, 13021, 13022, 13023, 13024, 13025 Extra Details: thermal stability, cooperative endotherm, surface hydrophobicity, structural changes

Submission Details

ID: y962nwf

Submitter: Connie Wang

Submission Date: April 24, 2018, 8:44 p.m.

Version: 1

Publication Details
Remeta DP;Krumbiegel M;Minetti CA;Puri A;Ginsburg A;Blumenthal R,Biochemistry (2002) Acid-induced changes in thermal stability and fusion activity of influenza hemagglutinin. PMID:11827552
Additional Information

Study Summary

Number of data points 27
Proteins Hemagglutinin ; Hemagglutinin
Unique complexes 1
Assays/Quantities/Protocols Experimental Assay: dHcal details:Additives Octyl-beta-glucoside(1%), ; Experimental Assay: Tm details:Additives Octyl-beta-glucoside(1%), ; Experimental Assay: dHvH details:Additives Octyl-beta-glucoside(1%), ; Experimental Assay: dHcal pH:5.0, details:Additives ; Experimental Assay: Tm pH:5.0, details:Additives ; Experimental Assay: dHvH pH:5.0, details:Additives ; Experimental Assay: dHcal details:Additives , pH:5.4 ; Experimental Assay: Tm details:Additives , pH:5.4 ; Experimental Assay: dHvH details:Additives , pH:5.4 ; Experimental Assay: dHcal pH:5.7, details:Additives ; Experimental Assay: Tm pH:5.7, details:Additives ; Experimental Assay: dHvH pH:5.7, details:Additives ; Experimental Assay: dHcal pH:6.0, details:Additives ; Experimental Assay: Tm pH:6.0, details:Additives ; Experimental Assay: dHvH pH:6.0, details:Additives ; Experimental Assay: dHcal pH:6.2, details:Additives ; Experimental Assay: Tm pH:6.2, details:Additives ; Experimental Assay: dHvH pH:6.2, details:Additives ; Experimental Assay: dHcal details:Additives , pH:6.5 ; Experimental Assay: Tm details:Additives , pH:6.5 ; Experimental Assay: dHvH details:Additives , pH:6.5 ; Experimental Assay: dHcal details:Additives , pH:7.0 ; Experimental Assay: Tm details:Additives , pH:7.0 ; Experimental Assay: dHvH details:Additives , pH:7.0 ; Experimental Assay: dHcal details:Additives ; Experimental Assay: Tm details:Additives ; Experimental Assay: dHvH details:Additives

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 UniProtKB Entries

Percent Identity Matching Chains Protein Accession Entry Name
600.0 A,B,C,D,E,F Hemagglutinin P03437 HEMA_I68A0
597.3 A,B,C,D,E,F Hemagglutinin Q91MA7 HEMA_I68A4
594.6 A,B,C,D,E,F Hemagglutinin P03436 HEMA_I68A6
594.6 A,B,C,D,E,F Hemagglutinin P03438 HEMA_I000X
593.6999999999999 A,B,C,D,E,F Hemagglutinin P03449 HEMA_I71A1
586.5 A,B,C,D,E,F Hemagglutinin P12583 HEMA_I80A6
586.5 A,B,C,D,E,F Hemagglutinin P19106 HEMA_I72A2
586.5 A,B,C,D,E,F Hemagglutinin P03439 HEMA_I72A3
586.5 A,B,C,D,E,F Hemagglutinin Q2ICR0 HEMA_I72A4
582.0 A,B,C,D,E,F Hemagglutinin Q1PUD9 HEMA_I73A5
581.1 A,B,C,D,E,F Hemagglutinin P03442 HEMA_I63A3
577.5 A,B,C,D,E,F Hemagglutinin P26134 HEMA_I76A3
582.3000000000001 A,B,C,D,E,F Hemagglutinin P12585 HEMA_I82A5
581.7 A,B,C,D,E,F Hemagglutinin P12588 HEMA_I85A2
582.3000000000001 A,B,C,D,E,F Hemagglutinin P12584 HEMA_I80A7
572.1 A,B,C,D,E,F Hemagglutinin P26138 HEMA_I78A4
574.8 A,B,C,D,E,F Hemagglutinin P03435 HEMA_I75A3
572.1 A,B,C,D,E,F Hemagglutinin Q2RFA5 HEMA_I76A6
563.4 A,B,C,D,E,F Hemagglutinin Q30NQ1 HEMA_I75A0
571.2 A,B,C,D,E,F Hemagglutinin P26139 HEMA_I77A4
578.4 A,B,C,D,E,F Hemagglutinin P11134 HEMA_I82A4
579.6 A,B,C,D,E,F Hemagglutinin P12587 HEMA_I85A1
576.0 A,B,C,D,E,F Hemagglutinin P43257 HEMA_I75A2
571.5 A,B,C,D,E,F Hemagglutinin P26135 HEMA_I74A2
576.9000000000001 A,B,C,D,E,F Hemagglutinin P12582 HEMA_I77A6
578.4 A,B,C,D,E,F Hemagglutinin P43258 HEMA_I76AD
570.9 A,B,C,D,E,F Hemagglutinin P43260 HEMA_I76AC
571.5 A,B,C,D,E,F Hemagglutinin P11133 HEMA_I78A9
271.5 A,C,E Hemagglutinin P26141 HEMA_I84A5
569.4 A,B,C,D,E,F Hemagglutinin Q2VND2 HEMA_I78A8
568.5 A,B,C,D,E,F Hemagglutinin P03440 HEMA_I77A8
569.4 A,B,C,D,E,F Hemagglutinin Q2VNF2 HEMA_I78A7
575.1 A,B,C,D,E,F Hemagglutinin P43259 HEMA_I77A7
573.0 A,B,C,D,E,F Hemagglutinin P12586 HEMA_I82A6
554.4 A,B,C,D,E,F Hemagglutinin Q03909 HEMA_I89A7
293.1 B,D,F Hemagglutinin Q2RCH5 HEMA_I80A4
284.70000000000005 B,D,F Hemagglutinin Q38SQ8 HEMA_I83A8
291.29999999999995 B,D,F Hemagglutinin P03441 HEMA_I79A0
289.79999999999995 B,D,F Hemagglutinin P12589 HEMA_I86A1
279.29999999999995 B,D,F Hemagglutinin P15658 HEMA_I63A2
295.5 A,C,E Hemagglutinin P04664 HEMA_I69A0
295.5 A,C,E Hemagglutinin P04663 HEMA_I70A0
288.0 B,D,F Hemagglutinin P17002 HEMA_I63A4
284.4 B,D,F Hemagglutinin P16994 HEMA_I72A0
282.9 B,D,F Hemagglutinin P17000 HEMA_I71A3
279.29999999999995 B,D,F Hemagglutinin P16995 HEMA_I76A8
277.79999999999995 B,D,F Hemagglutinin P16998 HEMA_I80AB
277.79999999999995 B,D,F Hemagglutinin Q82559 HEMA_I81A2
277.79999999999995 B,D,F Hemagglutinin Q08011 HEMA_I89A8
284.70000000000005 B,D,F Hemagglutinin O11283 HEMA_I89A2
270.9 B,D,F Hemagglutinin P16997 HEMA_I76AJ
270.9 B,D,F Hemagglutinin P19699 HEMA_I86A2
270.9 B,D,F Hemagglutinin P17001 HEMA_I86A3