A disease-associated glycine substitution in BP180 (type XVII collagen) leads to a local destabilization of the major collagen triple helix.
BP180 is a homotrimeric transmembrane protein with a carboxy-terminal ectodomain that forms an interrupted collagen triple helix. Null type mutations in the BP180 gene produce a recessive subepidermal blistering disease, non-Herlitz junctional epidermolysis bullosa. Like the null mutations, a glycine substitution (G627V) within the longest BP180 collagenous domain (COL15) is also associated with the recessive skin disease; however, unlike the null mutations, this glycine substitution appears to act in a dominant fashion to give rise to a novel form of random pitting dental enamel hypoplasia. The dominant effects of this mutation were thought to be due to alterations in the assembly and/or stability of this BP180 collagenous region. To further investigate this issue, a structural analysis was performed on recombinant forms of the wild type and G627V mutant BP180 ectodomain. Both proteins were found to form collagen-like triple helices with very similar Stokes radii and melting temperatures and exhibited very similar rates of synthesis, secretion and turn-over. Tryptic digestion analysis revealed that the mutant G627V-sec180e contains an additional highly sensitive proteolytic site that maps within the region of the mutation. Thus, the disease-associated G627V mutation in BP180 does not grossly alter protein structure, but causes a local destabilization of the triple-helix that exposes sensitive residues to the in vitro effects of trypsin and possibly affects its structure-function in vivo.
Department of Dermatology, Medical College of Wisconsin, Milwaukee, 53226, USA.
M
M
Olague-Marchan
S S
SS
Twining
M K
MK
Hacker
J A
JA
McGrath
L A
LA
Diaz
G J
GJ
Giudice
D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D000818:Animals; D001324:Autoantigens / Q000235:genetics / Q000378:metabolism*; D002352:Carrier Proteins; D002461:Cell Line, Transformed; D003094:Collagen / Q000235:genetics / Q000378:metabolism*; D003598:Cytoskeletal Proteins; D000071821:Dystonin; D015870:Gene Expression; D005998:Glycine / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D009419:Nerve Tissue Proteins; D024041:Non-Fibrillar Collagens; D011817:Rabbits; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D014357:Trypsin / Q000378:metabolism; D000097805:Collagen Type XVII
D001324:Autoantigens; D002352:Carrier Proteins; D003094:Collagen; D003598:Cytoskeletal Proteins; D000071821:Dystonin; D005998:Glycine; D009419:Nerve Tissue Proteins; D024041:Non-Fibrillar Collagens; D011993:Recombinant Fusion Proteins; D014357:Trypsin; D000097805:Collagen Type XVII; C486268:DST protein, human