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Title: Critical Role of Arg/Lys343 in the Species-Dependent Recognition of Phosphatidylinositol by Plumonary Surfactant Protein D

Abstract

Surfactant protein D (SP-D) plays important roles in lung host defense. However, it can also recognize specific host molecules and contributes to surfactant homeostasis. The major known surfactant-associated ligand is phosphatidylinositol (PI). Trimeric neck-carbohydrate recognition domains (NCRDs) of rat and human SP-D exhibited dose-dependent, calcium-dependent, and inositol-sensitive binding to solid-phase PI and to multilamellar PI liposomes. However, the rat protein exhibited a >5-fold higher affinity for solid-phase PI than the human NCRD. In addition, human dodecamers, but not full-length human trimers, efficiently coprecipitated with multilamellar PI liposomes in the presence of calcium. A human NCRD mutant resembling the rat and mouse proteins at position 343 (hR343K) showed much stronger binding to PI. A reciprocal rat mutant with arginine at the position of lysine 343 (rK343R) showed weak binding to PI, even weaker than that of the wild-type human protein. Crystal complexes of the human trimeric NCRD with myoinositol and inositol 1-phosphate showed binding of the equatorial OH groups of the cyclitol ring of the inositol to calcium at the carbohydrate binding site. Myoinositol binding occurred in two major orientations, while inositol 1-phosphate appeared primarily constrained to a single, different orientation. Our studies directly implicate the CRD in PI binding andmore » reveal unexpected species differences in PI recognition that can be largely attributed to the side chain of residue 343. In addition, the studies indicate that oligomerization of trimeric subunits is an important determinant of recognition of PI by human SP-D.« less

Authors:
; ; ; ; ; ;
Publication Date:
Research Org.:
Brookhaven National Laboratory (BNL) National Synchrotron Light Source
Sponsoring Org.:
Doe - Office Of Science
OSTI Identifier:
929900
Report Number(s):
BNL-80485-2008-JA
Journal ID: ISSN 0006-2960; TRN: US200822%%1075
DOE Contract Number:  
DE-AC02-98CH10886
Resource Type:
Journal Article
Journal Name:
Biochemistry
Additional Journal Information:
Journal Volume: 46; Journal ID: ISSN 0006-2960
Country of Publication:
United States
Language:
English
Subject:
59 BASIC BIOLOGICAL SCIENCES; AFFINITY; ANIMAL TISSUES; ARGININE; CALCIUM; CARBOHYDRATES; COMPLEXES; CRYSTALS; HOMEOSTASIS; HOST; INOSITOL; LIGANDS; LIPOSOMES; LUNGS; LYSINE; MOLECULES; MUTANTS; ORIENTATION; PROTEINS; RATS; RESIDUES; RINGS; SURFACTANTS; national synchrotron light source

Citation Formats

Crouch, E, McDonald, B, Smith, K, Roberts, M, Mealy, T, Seaton, B, and Head, J. Critical Role of Arg/Lys343 in the Species-Dependent Recognition of Phosphatidylinositol by Plumonary Surfactant Protein D. United States: N. p., 2007. Web. doi:10.1021/bi700037x.
Crouch, E, McDonald, B, Smith, K, Roberts, M, Mealy, T, Seaton, B, & Head, J. Critical Role of Arg/Lys343 in the Species-Dependent Recognition of Phosphatidylinositol by Plumonary Surfactant Protein D. United States. https://doi.org/10.1021/bi700037x
Crouch, E, McDonald, B, Smith, K, Roberts, M, Mealy, T, Seaton, B, and Head, J. Mon . "Critical Role of Arg/Lys343 in the Species-Dependent Recognition of Phosphatidylinositol by Plumonary Surfactant Protein D". United States. https://doi.org/10.1021/bi700037x.
@article{osti_929900,
title = {Critical Role of Arg/Lys343 in the Species-Dependent Recognition of Phosphatidylinositol by Plumonary Surfactant Protein D},
author = {Crouch, E and McDonald, B and Smith, K and Roberts, M and Mealy, T and Seaton, B and Head, J},
abstractNote = {Surfactant protein D (SP-D) plays important roles in lung host defense. However, it can also recognize specific host molecules and contributes to surfactant homeostasis. The major known surfactant-associated ligand is phosphatidylinositol (PI). Trimeric neck-carbohydrate recognition domains (NCRDs) of rat and human SP-D exhibited dose-dependent, calcium-dependent, and inositol-sensitive binding to solid-phase PI and to multilamellar PI liposomes. However, the rat protein exhibited a >5-fold higher affinity for solid-phase PI than the human NCRD. In addition, human dodecamers, but not full-length human trimers, efficiently coprecipitated with multilamellar PI liposomes in the presence of calcium. A human NCRD mutant resembling the rat and mouse proteins at position 343 (hR343K) showed much stronger binding to PI. A reciprocal rat mutant with arginine at the position of lysine 343 (rK343R) showed weak binding to PI, even weaker than that of the wild-type human protein. Crystal complexes of the human trimeric NCRD with myoinositol and inositol 1-phosphate showed binding of the equatorial OH groups of the cyclitol ring of the inositol to calcium at the carbohydrate binding site. Myoinositol binding occurred in two major orientations, while inositol 1-phosphate appeared primarily constrained to a single, different orientation. Our studies directly implicate the CRD in PI binding and reveal unexpected species differences in PI recognition that can be largely attributed to the side chain of residue 343. In addition, the studies indicate that oligomerization of trimeric subunits is an important determinant of recognition of PI by human SP-D.},
doi = {10.1021/bi700037x},
url = {https://www.osti.gov/biblio/929900}, journal = {Biochemistry},
issn = {0006-2960},
number = ,
volume = 46,
place = {United States},
year = {2007},
month = {1}
}