Sequence diversity of the Bla g 4 cockroach allergen, homologous to lipocalins, from Blattella germanica.
BACKGROUND
The cockroach allergen Bla g 4, a putative lipocalin, is known to exhibit frequent sequence variations. However, the previously reported cDNA sequences are truncated at the N terminus. This study was undertaken to investigate the mechanisms by which these sequence variations are generated.


METHODS
Rapid amplification of cDNA ends PCR and RT-PCR were performed to obtain the full sequence of the Bla g 4 cDNA, and PCR was also used to clone the Bla g 4 genomic DNA. In addition, Bla g 4 protein variants were analyzed by two-dimensional gel electrophoresis.


RESULTS
Nine additional amino acid residues at the N terminus of Bla g 4 were identified, and 2 genes encoding Bla g 4, both of which consisted of 5 exons, were cloned. Examination of 34 clones of Bla g 4 cDNA obtained by RT-PCR revealed 14 variants. In particular, Bla g 4 sequences showed frequent clusters of variations in residues 38-45, 61-82 and 144-163. Differences in cDNA sequences may imply that RNA sequences are edited after transcription. More than 10 spots were identified between pH 5 and 7 upon two-dimensional gel electrophoresis, indicating that multiple variants of Bla g 4 are produced at the protein level.


CONCLUSIONS
Genetic polymorphisms among individual cockroaches, the existence of multiple genes and sequence variations caused by RNA editing produce sequence diversity of Bla g 4, which may influence its allergenicity. The sequence information obtained in this study will be helpful for the standardization of the cockroach allergen and thereby aid in the development of diagnostics and immunotherapeutics.
Jeong
Kyoung Yong
KY
Department of Environmental Medical Biology and Institute of Tropical Medicine, Arthropods of Medical Importance Resource Bank, Seoul, Korea.
Yi
Myung-Hee
MH
Jeong
Kyoung-jin
KJ
Lee
Haeseok
H
Hong
Chein-Soo
CS
Yong
Tai-Soon
TS
D000485:Allergens / Q000737:chemistry* / Q000235:genetics* / Q000276:immunology; D000595:Amino Acid Sequence; D000818:Animals; D000906:Antibodies / Q000276:immunology; D052179:Antigens, Plant; D020048:Blattellidae / Q000737:chemistry / Q000235:genetics*; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000235:genetics; D005260:Female; D014644:Genetic Variation; D019476:Insect Proteins / Q000737:chemistry* / Q000235:genetics* / Q000276:immunology; D054834:Lipocalins / Q000235:genetics; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D008969:Molecular Sequence Data; D017386:Sequence Homology, Amino Acid
D000485:Allergens; D000906:Antibodies; D052179:Antigens, Plant; C097505:Blatella germanica allergen 4; D018076:DNA, Complementary; D019476:Insect Proteins; D054834:Lipocalins