Comparative sequence analysis of the VHL tumor suppressor gene

Comparative genome analysis may provide novel insights into gene evolution and function. To investigate the von Hippel-Lindau (VHL) disease tumor supp ressor gene, we sequenced the VHL gene in seven primate species. Comparativ e analysis was performed for human, primate, and rodent VHL genes and for a putative Caenorhabditis elegans VHL homologue identified by database analy sis. The VHL gene has two translation initiation sites (at codons 1 and 54) ; however, the relative importance of the full-length translation product ( pVHL(30)) and that translated from the second internal translation initiati on site (pVHL(19)) is unclear. The N-terminal sequence of pVHL(30) contains eight copies of a GXEEX acidic repeat motif in human and higher primates, but only three copies were present in the marmoset, and only one copy was p resent in rodent VHL genes. Evolutionary analysis suggested that the N-term inal repetitive sequence in pVHL(30) was of less functional importance than those regions present in both pVHL(30) and pVHL(19). The VHL gene product is reported to form complexes with various proteins including elongin B, el ongin C, VBP-1, fibronectin, Sp1, CUL2, and HIF-1. Although most of the reg ions in pVHL that had been implicated in binding specific proteins demonstr ated evolutionary conservation, the carboxy-terminal putative VBP-1 binding site was less well conserved, suggesting that VBP-1 binding may have less functional significance. Although an amino acid substitution (K171T) close to the pVHL elongin binding region was found in baboon, analysis of the str ucture of human pVHL suggested that this substitution would not interfere w ith pVHL/elongin C interaction. In general, there was a good correlation be tween the pVHL domains that demonstrated most evolutionary conservation and those that were most frequently mutated in tumors. Analysis of human/C, el egans conservation and human germline and somatic mutation patterns identif ied a highly conserved mutation cluster region between codons 74 and 90. Ho wever, this region is likely to be important for the structural integrity o f pVHL rather than representing an additional protein binding domain. (C) 2 000 Academic Press.