University of Oulu

Kaur, I., Ruskamo, S., Koivunen, J., Heljasvaara, R., Lackman, J., Izzi, V., Petäjä-Repo, U., Kursula, P., Pihlajaniemi, T. (2018) The N-terminal domain of unknown function (DUF959) in collagen XVIII is intrinsically disordered and highly O-glycosylated. Biochemical Journal, 475 (22), 3577-3593. doi:10.1042/BCJ20180405

The N-terminal domain of unknown function (DUF959) in collagen XVIII is intrinsically disordered and highly O-glycosylated

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Author: Kaur, Inderjeet1,2; Ruskamo, Salla2; Koivunen, Jarkko1,2;
Organizations: 1Oulu Center for Cell-Matrix Research, University of Oulu, Oulu FIN-90014, Finland
2Biocenter Oulu and Faculty of Biochemistry and Molecular Medicine, University of Oulu, Oulu FIN-90014, Finland
3Department of Biomedicine, University of Bergen, Bergen N-5020, Norway
4Centre for Cancer Biomarkers (CCBIO), University of Bergen, Bergen N-5020, Norway
5Medical Research Center Oulu and Research Unit of Biomedicine, Faculty of Medicine, University of Oulu, Oulu FIN-90014, Finland
Format: article
Version: accepted version
Access: open
Online Access: PDF Full Text (PDF, 1.6 MB)
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Language: English
Published: Portland Press, 2018
Publish Date: 2019-11-20


Collagen XVIII (ColXVIII) is a non-fibrillar collagen and proteoglycan that exists in three isoforms: short, medium and long. The medium and long isoforms contain a unique N-terminal domain of unknown function, DUF959, and our sequence-based secondary structure predictions indicated that DUF959 could be an intrinsically disordered domain. Recombinant DUF959 produced in mammalian cells consisted of ∼50% glycans and had a molecular mass of 63 kDa. Circular dichroism spectroscopy confirmed the disordered character of DUF959, and static light scattering indicated a monomeric state for glycosylated DUF959 in solution. Small-angle X-ray scattering showed DUF959 to be a highly extended, flexible molecule with a maximum dimension of ∼23 nm. Glycosidase treatment demonstrated considerable amounts of O-glycosylation, and expression of DUF959 in HEK293 SimpleCells capable of synthesizing only truncated O-glycans confirmed the presence of N-acetylgalactosamine-type O-glycans. The DUF959 sequence is characterized by numerous Ser and Thr residues, and this accounts for the finding that half of the recombinant protein consists of glycans. Thus, the medium and long ColXVIII isoforms contain at their extreme N-terminus a disordered, elongated and highly O-glycosylated mucin-like domain that is not found in other collagens, and we suggest naming it the Mucin-like domain in ColXVIII (MUCL-C18). As intrinsically disordered regions and their post-translational modifications are often involved in protein interactions, our findings may point towards a role of the flexible mucin-like domain of ColXVIII as an interaction hub affecting cell signaling. Moreover, the MUCL-C18 may also serve as a lubricant at cell–extracellular matrix interfaces.

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Series: Biochemical journal
ISSN: 0264-6021
ISSN-E: 1470-8728
ISSN-L: 0264-6021
Volume: 475
Issue: 22
Pages: 3577 - 3593
DOI: 10.1042/BCJ20180405
Type of Publication: A1 Journal article – refereed
Field of Science: 1182 Biochemistry, cell and molecular biology
Funding: This work was supported by grants from Biocenter Oulu, the Sigrid Jusélius Foundation and the Academy of Finland [grants nos 294617, 275225 and 308867].
Academy of Finland Grant Number: 294617
Detailed Information: 294617 (Academy of Finland Funding decision)
275225 (Academy of Finland Funding decision)
308867 (Academy of Finland Funding decision)
Copyright information: © 2018 The Author(s). Published by Portland Press Limited on behalf of the Biochemical Society.