The overexpression of homeotic complex gene Ultrabithorax in the post-embryonic neuronal lineages of the ventral nervous system in Drosophila melanogaster

This study uses a molecular technique called MARCM (Mosaic Analysis with a Repressible Cell Marker) to label neuronal lineages that overexpress the Hox gene Ultrabithorax (Ubx) in an unlabeled, wild type background. The results indicate that the overexpression of Ubx is sufficient to transform more anterior neuronal lineages to themorphology of their more posterior counterparts. The data presented here begin to elucidate the role that the Hox genes have in shaping segment-specific neural connections in the post-embryonic ventral nervous system.

Crystal structure of a CAP-DNA complex: the DNA is bent by 90 degrees

The 3 angstrom resolution crystal structure of the Escherichia coli catabolite gene activator protein (CAP) complexed with a 30-base pair DNA sequence shows that the DNA is bent by 900. This bend results almost entirely from two 400 kinks that occur between TG/CA base pairs at positions 5 and 6 on each side of the dyad axis of the complex. DNA sequence discrimination by CAP derives both from sequence-dependent distortion of the DNA helix and from direct hydrogen-bonding interactions between three protein side chains and the exposed edges of three base pairs in the major groove of the DNA. The structure of this transcription factor-DNA complex provides insights into possible mechanisms of transcription activation