Lupus autoantibodies to double-stranded DNA cross-react with ribosomal protein S1.
One cDNA clone (G7) was isolated from a lambda gt11 human liver cDNA library by the reaction with a serum containing anti-dsDNA Abs and was ligated into pGEX-1 lambda T vector. All the 10 SLE sera with anti-dsDNA, 2 samples of human monoclonal anti-dsDNA (33.C9 and 33.H11), and 2 affinity-purified anti-dsDNA Abs recognized the glutathione S-transferase fusion protein expressed by G7 (G7-FP). Ab binding to the recombinant protein expressed by G7 (G7-RP) and to G7-FP was inhibited completely by calf thymus dsDNA. The cDNA was 1314 nucleotides in length and contained an open reading frame encoding 352 amino acids. However, it seems to be a partial length cDNA because the affinity-purified Ab from G7-FP recognized only a 104-kDa protein on Western blot using MOLT4 cell extract. The nucleotide sequence of G7 was homologous (99% identity) to a cDNA encoding human ribosomal protein (r-protein) S1 homologue mRNA. The encoded protein contains repeating residues as a feature of r-proteins S1. Cytoplasmic and nucleolar staining of 33.H11 on indirect immunofluorescence (IF) using HEP 2 cells was inhibited by both G7-RP and calf thymus dsDNA. On ELISA, 33.H11 had a higher affinity for G7-RP than for DNA while 33.C9 had a higher affinity for DNA than for G7-RP and binds nuclei on IF. We conclude that G7 encodes a portion of human r-protein S1 and anti-dsDNA Abs cross-react with this protein.
Tsuzaka
K
K
Arthritis and Immunology Program, Oklahoma Medical Research Foundation, Oklahoma City 73104, USA.
Leu
A K
AK
Frank
M B
MB
Movafagh
B F
BF
Koscec
M
M
Winkler
T H
TH
Kalden
J R
JR
Reichlin
M
M
D000595:Amino Acid Sequence; D000974:Antibodies, Antinuclear / Q000276:immunology*; D000915:Antibody Affinity; D000918:Antibody Specificity; D001324:Autoantigens / Q000276:immunology*; D001483:Base Sequence; D003429:Cross Reactions; D004247:DNA / Q000276:immunology*; D019084:Fluorescent Antibody Technique, Indirect; D006801:Humans; D008180:Lupus Erythematosus, Systemic / Q000276:immunology*; D008969:Molecular Sequence Data; D012269:Ribosomal Proteins / Q000276:immunology*; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid
D000974:Antibodies, Antinuclear; D001324:Autoantigens; D012269:Ribosomal Proteins; C015494:ribosomal protein S1; D004247:DNA