Carbohydrates located on the top of the "cap" contribute to the adhesive and enzymatic functions of vascular adhesion protein-1.
Vascular adhesion protein 1 (VAP-1) is an endothelial adhesion molecule with an enzymatic activity. It deaminates biogenic amines, resulting in the formation of aldehydes and hydrogen peroxide. During the enzymatic reaction a transient Schiff base is formed between endothelial VAP-1 and its leukocytic ligand, and this interaction is important for lymphocyte adhesion. VAP-1 monomer has six potential N-linked, and three putative O-linked glycosylation sites and an SSSS sequence potentially forming an attachment site for an adjacent O-linked site. In this work we modeled the carbohydrate decorations on a structural model of VAP-1, and studied which of those potential glycosylation sites are utilized, and whether those decorations accessible to a lymphocyte ligand are important in lymphocyte adhesion and enzymatic activity of VAP-1. We show that, unlike the O-linked attachment sites, all six N-linked glycosylation sites are in use. Furthermore, mutation of the N-linked attachment sites strategically located on the top of the molecule reduces lymphocyte adhesion in non-static conditions, and enhances the catalytic activity of membrane-bound human VAP-1 in static conditions, suggesting that glycosylation regulates the functional properties of VAP-1.
Maula
Sanna-Mari
SM
National Public Health Institute, MediCity Research Laboratory, Department of Medical Microbiology and Turku University School of Biomedical Sciences, Turku University, Turku, Finland.
Salminen
Tiina
T
Kaitaniemi
Sam
S
Nymalm
Yvonne
Y
Smith
David J
DJ
Jalkanen
Sirpa
S
D006631:Amine Oxidase (Copper-Containing) / Q000737:chemistry / Q000235:genetics / Q000276:immunology / Q000502:physiology*; D000818:Animals; D016466:CHO Cells; D002448:Cell Adhesion / Q000276:immunology; D015815:Cell Adhesion Molecules / Q000737:chemistry / Q000235:genetics / Q000276:immunology / Q000502:physiology*; D006224:Cricetinae; D042783:Endothelial Cells / Q000166:cytology / Q000201:enzymology / Q000276:immunology; D005434:Flow Cytometry; D006031:Glycosylation; D015151:Immunoblotting; D007525:Isoelectric Focusing; D008214:Lymphocytes / Q000166:cytology / Q000201:enzymology / Q000276:immunology; D008958:Models, Molecular; D016297:Mutagenesis, Site-Directed; D051381:Rats; D020775:Thoracic Surgery, Video-Assisted; D014162:Transfection
D015815:Cell Adhesion Molecules; C076668:AOC3 protein, human; D006631:Amine Oxidase (Copper-Containing)