A single amino acid substitution in the Bombyx-specific mucin-like membrane protein causes resistance to Bombyx mori densovirus.

Abstract

Bombyx mori densovirus type 1 (BmDV) is a pathogen that causes flacherie disease in the silkworm. The absolute nonsusceptibility to BmDV among certain silkworm strains is determined independently by two genes, nsd-1 and Nid-1. However, neither of these genes has been molecularly identified to date. Here, we isolated the nsd-1 gene by positional cloning and characterized the properties of its product, NSD-1. Sequence and biochemical analyses revealed that this gene encodes a Bombyx-specific mucin-like glycoprotein with a single transmembrane domain. The NSD-1 protein was specifically expressed in the larval midgut epithelium, the known infection site of BmDV. Sequence analysis of the nsd-1 gene from 13 resistant and 12 susceptible strains suggested that a specific arginine residue in the extracellular tail of the NSD-1 protein was common among susceptible strains. Germline transformation of the susceptible-type nsd-1 (with a single nucleotide substitution) conferred partial susceptibility to resistant larvae, indicating that the +  nsd-1 gene is required for the susceptibility of B. mori larvae to BmDV and the susceptibility is solely a result of the substitution of a single amino acid with arginine. Taken together, our results provide striking evidence that a novel membrane-bound mucin-like protein functions as a cell-surface receptor for a densovirus.

• Authors: Katsuhiko Ito, Kurako Kidokoro, Susumu Katsuma, Hideki Sezutsu, Keiro Uchino, Isao Kobayashi, Toshiki Tamura, Kimiko Yamamoto, Kazuei Mita, Toru Shimada, Keiko Kadono-Okuda
• Journal: Scientific reports (Sci Rep) Vol. 8 Issue 1 Pg. 7430 (05 09 2018) ISSN: 2045-2322 [Electronic] England
• PMID: 29743532 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Insect Proteins
• Membrane Proteins
• Mucins

Topics

• Amino Acid Substitution
• Animals
• Bombyx (metabolism, physiology, virology)
• Cloning, Molecular
• Insect Proteins (genetics, metabolism)
• Insect Viruses (physiology)
• Membrane Proteins (genetics, metabolism)
• Mucins (metabolism)
• Protein Transport
• Species Specificity
• Transformation, Genetic