BIOASSAYING PUTATIVE RNA-BINDING MOTIFS IN A PROTEIN ENCODED BY A GENE THAT INFLUENCES COURTSHIP AND VISUALLY MEDIATED BEHAVIOR IN DROSOPHILA - IN-VITRO MUTAGENESIS OF NONA

The no-on-transient-A (nonA) gene of Drosophila melanogaster influence s vision, courtship song, and viability. The nonA-encoded polypeptide is inferred to bind single-stranded nucleic acids. Although sequence-a nalysis of NONA implies that it belongs to a special interspecific fam ily of this protein type, it does contain two classical RNA recognitio n motifs (RRM). Their behavioral significance was assayed by generatin g transgenic strains that were singly or multiply mutated within the r elatively N-terminal motif (RRM1) or within RRM2. Neither class of mut ation affected NONA binding to polytene chromosomes. The former mutati ons led to extremely low viability, accompanied by diminished adult lo ngevities that were much worse than for a nonA-null mutant, implying t hat faulty interpolypeptide interactions might accompany the effects o f the amino-acid substitutions within RRM1. All in vitro-mutated types caused optomotor blindness and an absence of transient spikes in the electroretinogram. Courtship analysis discriminated between the effect s of the mutations: the RRM2-mutated type generated song pulses and tr ains that tended to be mildly mutant. These phenotypic abnormalities r einforce the notion that nonA's ubiquitous expression has its most imp ortant consequences in the optic lobes, the thoracic ganlia, or both, depending in part on the nonA allele.