Pivotal Advance: Interconversion between pure chemotactic ligands and chemoattractant/secretagogue ligands of neutrophil C5a receptor by a single amino acid substitution

Journal of Leukocyte Biology: An Official Publication of the Reticuloendothelial Society

关键词: Skp;    site‐;    directed mutant protein;    respiratory burst reaction;    cytoplasmic Ca2+ influx;    G protein‐;    coupled receptor;   

DOI  :  10.1189/jlb.1009649

学科分类：生理学

来源: Federation of American Societies for Experimental Biology

【 摘 要 】

SkpderivedfromEscherichiacoliattractsleukocytesasapurechemotacticligandoftheC5areceptor[1].WeidentifiedthesubmolecularregionofSkpthatbindsandactivatestheC5areceptortobe‐Gln103‐Asp104‐Arg105‐usingsyntheticpeptidefragmentsandsite‐directedmutantsofSkp.AstheC5aaminoacidresidueequivalenttoGln103ofSkpisLeu72,wepreparedaGln103Leu‐Skpmutantasarecombinantprotein.Withthismutation,Skpgainedsecretagoguefunctionsincludinginductionoftherespiratoryburstandgranulereleasereactionsandleukotrienegeneration,inadditiontothechemoattractiondisplayedbyC5a.However,whenwesubstitutedLeu72withGlninC5a,theL72Q‐C5amutantlargelylostitssecretagoguefunction.Thesefunctionalconversionswerereproducedusingsyntheticpeptidesmimickingthereceptor‐binding/‐activatingregionsoftherecombinantproteins.Receptor‐bindingassaysusingthemimickingpeptidesdemonstratedonlyasmalldifferencebetweentheLeu72‐C5aandGln72‐C5apeptides.Consistently,L72Q‐C5aapparentlyantagonizedC5asecretagoguefunction.Theseresultsindicatethatthedifferencebetweenachemotacticresponseandacombinedchemotactic/secretoryresponsecanbeattributednottothenatureofthereceptorbuttoguidancebytheligand,atleastinthecaseofC5areceptor‐mediatedleukocyteresponses...

【 授权许可】

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