Molecular basis for governing the morphology of type-I collagen fibrils by Osteomodulin

• Published in: Communications biology Vol. 1; no. 1; p. 33
• Main Authors: Tashima, Takumi, Nagatoishi, Satoru, Caaveiro, Jose M. M., Nakakido, Makoto, Sagara, Hiroshi, Kusano-Arai, Osamu, Iwanari, Hiroko, Mimuro, Hitomi, Hamakubo, Takao, Ohnuma, Shin-ichi, Tsumoto, Kouhei
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 19.04.2018; Nature Publishing Group
• Subjects: 13/1; 14/28; 631/45; 631/45/470; 631/45/535/1266; 631/535/1258; 82/103; 82/16; 82/29; 82/80; 82/83; Biology; Biomedical and Life Sciences; Collagen; Electrostatic properties; Extracellular matrix; Fibrillogenesis; Leucine; Life Sciences; Proteins; Proteoglycans
• ISSN: 2399-3642; 2399-3642
• DOI: 10.1038/s42003-018-0038-2

Small leucine-rich repeat proteoglycan (SLRP) proteins have an important role in the organization of the extracellular matrix, especially in the formation of collagen fibrils. However, the mechanism governing the shape of collagen fibrils is poorly understood. Here, we report that the protein Osteomodulin (OMD) of the SLRP family is a monomeric protein in solution that interacts with type-I collagen. This interaction is dominated by weak electrostatic forces employing negatively charged residues of OMD, in particular Glu284 and Glu303, and controlled by entropic factors. The protein OMD establishes a fast-binding equilibrium with collagen, where OMD may engage not only with individual collagen molecules, but also with the growing fibrils. This weak electrostatic interaction is carefully balanced so it modulates the shape of the fibrils without compromising their viability. Takumi Tashima and colleagues provide structural insights into how collagen fibrils are shaped by Osteomodulin. Osteomodulin keeps a fast-binding equilibrium with the collagen fibrils to slow down its growth, promoting the formation of uniform, intact collagen fibrils.