Tyrosine polysulfation of human salivary histatin 1. A post-translational modification specific of the submandibular gland.
Histatin 1 (His-1) derivatives showing serial mass increases of 80.0 +/- 0.1 Da were detected in human saliva by HPLC-ESI-MS. The same derivatives were also found in granules of submandibular glands and secretions of submandibular/sublingual glands, but not in granules and secretions of parotid glands. Only one phosphate group was present in His-1 and its derivatives, since treatment with alkaline phosphatase provided an 80.0 Da mass decrease. His-1 derivatives were almost completely transformed into His-1 by treatment with 1 M HCl at 100 degrees C, suggesting the presence of O-sulfotyrosine, which is more labile than phospho-Tyr to acidic hydrolysis. CE-MS analysis of pronase extensive digestion of derivatives confirmed the presence of sulfotyrosine. Derivatives were digested by trypsin, proteinase K, and protease V-8 and analyzed by different MS strategies. The results allowed locating sulfation on the last four tyrosines (Tyr 27, 30, 34, and 36). This study is the first report of the gland-specific sulfation of a salivary phosphopeptide in vivo.
Cabras
Tiziana
T
Department of Sciences Applied to Biosystems, Cagliari University, Cagliari, Italy.
Fanali
Chiara
C
Monteiro
Joana A
JA
Amado
Francisco
F
Inzitari
Rosanna
R
Desiderio
Claudia
C
Scarano
Emanuele
E
Giardina
Bruno
B
Castagnola
Massimo
M
Messana
Irene
I
D000595:Amino Acid Sequence; D002851:Chromatography, High Pressure Liquid; D019075:Electrophoresis, Capillary; D019286:Endopeptidase K / Q000737:chemistry; D054808:Histatins; D006801:Humans; D013058:Mass Spectrometry; D008969:Molecular Sequence Data; D010710:Phosphates / Q000032:analysis; D010748:Phosphopeptides / Q000737:chemistry / Q000378:metabolism*; D011499:Protein Processing, Post-Translational; D012471:Salivary Proteins and Peptides / Q000737:chemistry / Q000378:metabolism*; D012697:Serine Endopeptidases / Q000737:chemistry; D021241:Spectrometry, Mass, Electrospray Ionization; D013363:Submandibular Gland / Q000378:metabolism*; D013431:Sulfates / Q000032:analysis / Q000378:metabolism*; D014357:Trypsin / Q000737:chemistry; D014443:Tyrosine / Q000031:analogs & derivatives / Q000032:analysis / Q000378:metabolism*
D054808:Histatins; D010710:Phosphates; D010748:Phosphopeptides; D012471:Salivary Proteins and Peptides; D013431:Sulfates; C068074:HTN1 protein, human; C005662:tyrosine O-sulfate; D014443:Tyrosine; D012697:Serine Endopeptidases; C028344:glutamyl endopeptidase; D014357:Trypsin; D019286:Endopeptidase K