N-terminal segments are the functional domains of CLN3-encoded battenin for protein interactions.
OBJECTIVE
Batten disease (BD), the juvenile form of neuronal ceroid lipofuscinosis (NCLs), is pathological characterized by finding lysosomal storage of autofluorescent lipofuscins with unique ultrastructural profiles. The gene underlying BD is designated CLN3 and encodes a protein, Battenin, of unknown function that localizes in lysosomes and/or mitochondria. Previously, we hypothesized that Battenin associates with other membrane protein(s) to form a membrane complex. Dysfunction of this complex could result in the pathological changes of BD, and possibly in other NCLs. Two such membranous proteins, the slow and fast Battenin-interactive proteins (BIPs and BIPf) of unknown functions, have been identified. In this study, we have characterized the functional domains of Battenin that interact with both BIP proteins.


METHODS
Protein-protein interactions with a yeast two-hybrid system were employed. A "deletion assay" was employed to localize the interactive segment(s). Different lengths of cDNA sequences lacking exon 1-5 were used to express CLN3-encoded proteins lacking N-terminal segments in the yeast two-hybrid system. N-terminal exons of CLN3 were deleted with PCR-cloning strategies.


RESULTS
We eliminated the possibility of interacting domains from the exon 7-encoded region because both Battenin and mBattenin interact with the BIP proteins. We have shown that peptide sequences encoded by exons 2 and 4 of CLN3 gene include the functional domains by which Battenin interacts with the BIP proteins.


CONCLUSIONS
Our studies provide evidence that the N-terminus of Battenin is the functional domain for these protein interactions.
Moroziewicz
Dorota N
DN
Department of Human Genetics, New York State Institute for Basic Research in Developmental Disabilities, Staten Island, NY 10314, USA.
Ju
Weina
W
Zhong
Rocksheng
R
Zhong
Nanbert
N
D018076:DNA, Complementary / Q000235:genetics; D006801:Humans; D008562:Membrane Glycoproteins / Q000235:genetics*; D018832:Molecular Chaperones / Q000235:genetics*; D009472:Neuronal Ceroid-Lipofuscinoses / Q000235:genetics; D016366:Open Reading Frames; D054730:Protein Interaction Domains and Motifs
C105199:CLN3 protein, human; D018076:DNA, Complementary; D008562:Membrane Glycoproteins; D018832:Molecular Chaperones