CONSERVATIVE VAL(47) RESIDUE OF POU HOMEODOMAIN - ROLE IN DNA RECOGNITION

Conservative Val(47) residue, located in the third recognition helix o f the Oct-2 POU domain, was alternately substituted with other 19 amin o acids. Affinity and specificity of interaction with oct-site ATGCAAA NGA and homeo-specific site ATAANGA mere determined for all mutants. T he wild type protein (with Val(47)) has maximal affinity and specifici ty in POU domain interaction with octamer sequence. However, V47I muta nt showed stronger interaction with homeo-specific site. The highest s pecificity of interaction with homeo-site was recorded for V47S mutant . We conclude that only Val(47) provides sequence-specific high-affini ty binding of POU proteins with octamer targets other than the homeo-s pecific site. It is shown also that damages caused by point mutations may be at least partially compensated by participation in the oct-site recognition of both POUh and POUs domains. (C) 1997 Federation of Eur opean Biochemical Societies.