Structural analysis and lipid-binding properties of recombinant human surfactant protein A derived from one or both genes

I. García-Verdugo, G. Wang, Joanna Floros, C. Casals

Research output: Contribution to journalArticle

47 Citations (Scopus)

Abstract

Surfactant protein A (SP-A) constitutes an important part of the innate immune defense in the lung. In humans there are two functional genes (SP-A1 and SP-A2). The functional importance of having two distinct chain types in human SP-A is undefined. Amino acid substitutions in the primary structure of the protein may have effects on structural stability or on activity. To address this issue, SP-A1, SP-A2, and coexpressed SP-A1/SP-A2 variants were in vitro expressed in insect cells, purified, and used for study. We found the following: (1) Human SP-A variants expressed in insect cells, derived from one gene (SP-A1 or SP-A2) or both genes, differ in the relative extent and heterogeneity of oligomerization. SP-A1 and SP-A2 exist in small oligomeric forms, whereas coexpressed SP-A1/SP-A2 products favor the formation of larger oligomers. (2) Circular dichroic and fluorescence spectroscopic studies identified structural differences between SP-A variants in the collagen domain, with SP-A2 being more stable than SP-A1 but not in the calcium binding region. Recombinant human SP-A variants expressed in insect cells exhibit a lower melting temperature compared to native human SP-A. Oligomerization does not increase the thermal stability of the collagen domain of coexpressed SP-A1/SP-A2. (3) The ability of SP-A to undergo self-aggregation and induce phospholipid and bacterial lipopolysaccharide aggregation is greater for SP-A2 than for coexpressed SP-A1/SP-A2, which in turn is greater than that observed for SP-A1. The presence of SP-A1 polypeptide chains in coexpressed products modulates functional capabilities of SPA, which depend on both the collagen and globular domains.

Original languageEnglish (US)
Pages (from-to)14041-14053
Number of pages13
JournalBiochemistry
Volume41
Issue number47
DOIs
StatePublished - Nov 26 2002

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Pulmonary Surfactant-Associated Protein A
varespladib methyl
Structural analysis
Genes
Lipids
Oligomerization
Collagen
Insects
Agglomeration
Oligomers
Melting point
Lipopolysaccharides
Phospholipids
Thermodynamic stability
Substitution reactions
Fluorescence
Calcium
Amino Acids
Amino Acid Substitution
Peptides

All Science Journal Classification (ASJC) codes

  • Biochemistry

Cite this

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title = "Structural analysis and lipid-binding properties of recombinant human surfactant protein A derived from one or both genes",
abstract = "Surfactant protein A (SP-A) constitutes an important part of the innate immune defense in the lung. In humans there are two functional genes (SP-A1 and SP-A2). The functional importance of having two distinct chain types in human SP-A is undefined. Amino acid substitutions in the primary structure of the protein may have effects on structural stability or on activity. To address this issue, SP-A1, SP-A2, and coexpressed SP-A1/SP-A2 variants were in vitro expressed in insect cells, purified, and used for study. We found the following: (1) Human SP-A variants expressed in insect cells, derived from one gene (SP-A1 or SP-A2) or both genes, differ in the relative extent and heterogeneity of oligomerization. SP-A1 and SP-A2 exist in small oligomeric forms, whereas coexpressed SP-A1/SP-A2 products favor the formation of larger oligomers. (2) Circular dichroic and fluorescence spectroscopic studies identified structural differences between SP-A variants in the collagen domain, with SP-A2 being more stable than SP-A1 but not in the calcium binding region. Recombinant human SP-A variants expressed in insect cells exhibit a lower melting temperature compared to native human SP-A. Oligomerization does not increase the thermal stability of the collagen domain of coexpressed SP-A1/SP-A2. (3) The ability of SP-A to undergo self-aggregation and induce phospholipid and bacterial lipopolysaccharide aggregation is greater for SP-A2 than for coexpressed SP-A1/SP-A2, which in turn is greater than that observed for SP-A1. The presence of SP-A1 polypeptide chains in coexpressed products modulates functional capabilities of SPA, which depend on both the collagen and globular domains.",
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Structural analysis and lipid-binding properties of recombinant human surfactant protein A derived from one or both genes. / García-Verdugo, I.; Wang, G.; Floros, Joanna; Casals, C.

In: Biochemistry, Vol. 41, No. 47, 26.11.2002, p. 14041-14053.

Research output: Contribution to journalArticle

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AU - García-Verdugo, I.

AU - Wang, G.

AU - Floros, Joanna

AU - Casals, C.

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