Modification of surfactant protein D by reactive oxygen-nitrogen intermediates is accompanied by loss of aggregating activity, in vitro and in vivo.
Surfactant protein D (SP-D) is an important effector of innate immunity. We have previously shown that SP-D accumulates at sites of acute bacterial infection and neutrophil infiltration, a setting associated with the release of reactive species such as peroxynitrite. Incubation of native SP-D or trimeric SP-D lectin domains (NCRDs) with peroxynitrite resulted in nitration and nondisulfide cross-linking. Modifications were blocked by peroxynitrite scavengers or pH inactivation of peroxynitrite, and mass spectroscopy confirmed nitration of conserved tyrosine residues within the C-terminal neck and lectin domains. Mutant NCRDs lacking one or more of the tyrosines allowed us to demonstrate preferential nitration of Tyr314 and the formation of Tyr228-dependent cross-links. Although there was no effect of peroxynitrite or tyrosine mutations on lectin activity, incubation of SP-D dodecamers or murine lavage with peroxynitrite decreased the SP-D-dependent aggregation of lipopolysaccharide-coated beads, supporting our hypothesis that defective aggregation results from abnormal cross-linking. We also observed nitration, cross-linking of SP-D, and a significant decrease in SP-D-dependent aggregating activity in the lavage of mice acutely exposed to nitrogen dioxide. Thus, modification of SP-D by reactive oxygen-nitrogen species could contribute to alterations in the structure and function of SP-D at sites of inflammation in vivo.
Matalon
Sadis
S
Department of Anesthesiology, University of Alabama, Birmingham, Alabama, USA.
Shrestha
Kedar
K
Kirk
Marion
M
Waldheuser
Stephanie
S
McDonald
Barbara
B
Smith
Kelly
K
Gao
Zhiqian
Z
Belaaouaj
Abderrazzak
A
Crouch
Erika C
EC
D000595:Amino Acid Sequence; D000818:Animals; D001992:Bronchoalveolar Lavage Fluid / Q000276:immunology; D006801:Humans; D051379:Mice; D008981:Molsidomine / Q000031:analogs & derivatives* / Q000737:chemistry; D009585:Nitrogen Dioxide / Q000737:chemistry; D030421:Peroxynitrous Acid / Q000737:chemistry*; D020836:Protein Structure, Quaternary; D017434:Protein Structure, Tertiary / Q000187:drug effects; D037663:Pulmonary Surfactant-Associated Protein D / Q000737:chemistry* / Q000235:genetics; D051381:Rats; D011994:Recombinant Proteins; D053719:Tandem Mass Spectrometry; D014443:Tyrosine / Q000031:analogs & derivatives / Q000138:chemical synthesis / Q000737:chemistry / Q000235:genetics
D037663:Pulmonary Surfactant-Associated Protein D; D011994:Recombinant Proteins; D030421:Peroxynitrous Acid; C002744:3-nitrotyrosine; D014443:Tyrosine; C002385:linsidomine; D008981:Molsidomine; D009585:Nitrogen Dioxide