title: Proteomic Evidence for Components of Spider Silk Synthesis from Black Widow Silk Glands and Fibers.
abstract: Spider silk research has largely focused on spidroins, proteins that are the primary components of spider silk fibers. Although a number of spidroins have been characterized, other types of proteins associated with silk synthesis are virtually unknown. Previous analyses of tissue-specific RNA-seq libraries identified 647 predicted genes that were differentially expressed in silk glands of the Western black widow, Latrodectus hesperus. Only ∼5% of these silk-gland specific transcripts (SSTs) encode spidroins; although the remaining predicted genes presumably encode other proteins associated with silk production, this is mostly unverified. Here, we used proteomic analysis of multiple silk glands and dragline silk fiber to investigate the translation of the differentially expressed genes. We find 48 proteins encoded by the differentially expressed transcripts in L. hesperus major ampullate, minor ampullate, and tubuliform silk glands and detect 17 SST encoded proteins in major ampullate silk fibers. The observed proteins include known silk-related proteins, but most are uncharacterized, with no annotation. These unannotated proteins likely include novel silk-associated proteins. Major and minor ampullate glands have the highest overlap of identified proteins, consistent with their shared, distinctive ampullate shape and the overlapping functions of major and minor ampullate silks. Our study substantiates and prioritizes predictions from differential expression analysis of spider silk gland transcriptomes.
authors: Department of Biology, University of California , Riverside, California 92521, United States.
authors: Ro Crystal
authors: RC
authors: Chaw
authors: Department of Biology, University of California , Riverside, California 92521, United States.
authors: Sandra M
authors: SM
authors: Correa-Garhwal
authors: Department of Biology, Washington and Lee University , Lexington, Virginia 24450, United States.
authors: Thomas H
authors: TH
authors: Clarke
authors: Department of Biology, Washington and Lee University , Lexington, Virginia 24450, United States.
authors: Nadia A
authors: NA
authors: Ayoub
authors: Department of Biology, University of California , Riverside, California 92521, United States.
authors: Cheryl Y
authors: CY
authors: Hayashi
mesh_terms: D000818:Animals; D002853:Chromatography, Liquid; D002918:Chymotrypsin / Q000737:chemistry; D005260:Female; D005786:Gene Expression Regulation; D015723:Gene Library; D019476:Insect Proteins / Q000235:genetics / Q000302:isolation & purification* / Q000378:metabolism; D010446:Peptide Fragments / Q000032:analysis; D059748:Proteolysis; D020543:Proteome / Q000235:genetics / Q000302:isolation & purification* / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics* / Q000378:metabolism; D047011:Silk / Q000096:biosynthesis / Q000737:chemistry* / Q000235:genetics; D013112:Spiders / Q000235:genetics* / Q000378:metabolism; D053719:Tandem Mass Spectrometry; D014158:Transcription, Genetic; D014357:Trypsin / Q000737:chemistry
chemical_list: D019476:Insect Proteins; D010446:Peptide Fragments; D020543:Proteome; D012333:RNA, Messenger; D047011:Silk; D002918:Chymotrypsin; D014357:Trypsin
keywords: Ampullate silk glands; Latrodectus hesperus; dragline silk; mass spectrometry; silk fiber proteome; silk gland proteome; silk proteins; spider; spidroins; tubuliform glands