The Drosophila BRM complex facilitates global transcription by RNA polymerase II.

Drosophila brahma (brm) encodes the ATPase subunit of a 2 MDa complex that is related to yeast SWI/SNF and other chromatin-remodeling complexes. BRM was identified as a transcriptional activator of Hox genes required for the specification of body segment identities. To clarify the role of the BRM complex in the transcription of other genes, we examined its distribution on larval salivary gland polytene chromosomes.

The HMG-domain protein BAP111 is important for the function of the BRM chromatin-remodeling complex in vivo.

The Drosophila trithorax group gene brahma (brm) encodes the ATPase subunit of a SWI/SNF-like chromatin-remodeling complex. A key question about chromatin-remodeling complexes is how they interact with DNA, particularly in the large genomes of higher eukaryotes. Here, we report the characterization of BAP111, a BRM-associated protein that contains a high mobility group (HMG) domain predicted to bind distorted or bent DNA.

The ISWI chromatin-remodeling protein is required for gene expression and the maintenance of higher order chromatin structure in vivo.

Drosophila ISWI, a highly conserved member of the SWI2/SNF2 family of ATPases, is the catalytic subunit of three chromatin-remodeling complexes: NURF, CHRAC, and ACF. To clarify the biological functions of ISWI, we generated and characterized null and dominant-negative ISWI mutations. We found that ISWI mutations affect both cell viability and gene expression during Drosophila development.

The Drosophila kismet gene is related to chromatin-remodeling factors and is required for both segmentation and segment identity.

The Drosophila kismet gene was identified in a screen for dominant suppressors of Polycomb, a repressor of homeotic genes. Here we show that kismet mutations suppress the Polycomb mutant phenotype by blocking the ectopic transcription of homeotic genes. Loss of zygotic kismet function causes homeotic transformations similar to those associated with loss-of-function mutations in the homeotic genes Sex combs reduced and Abdominal-B.

Nucleotides in 23S rRNA protected by the association of 30S and 50S ribosomal subunits.

We have studied the effect of subunit association on the accessibility of nucleotides in 23S and 5S rRNA. Escherichia coli 50S subunits and 70S ribosomes were subjected to a combination of chemical probes and the sites of attack identified by primer extension. Since the ribose groups and all of the bases were probed, the present study provides a comprehensive map of the nucleotides that are likely to be involved in subunit-subunit interactions.

Genetic analysis of brahma: the Drosophila homolog of the yeast chromatin remodeling factor SWI2/SNF2.

The Drosophila brahma (brm) gene encodes an activator of homeotic genes related to the yeast chromatin remodeling factor SWI2/SNF2. Here, we report the phenotype of null and dominant-negative brm mutations. Using mosaic analysis, we found that the complete loss of brm function decreases cell viability and causes defects in the peripheral nervous system of the adult.

Dynamics of in vitro assembly of 16 S rRNA into 30 S ribosomal subunits.

One of the important unsolved problems in the ribosome field is the molecular basis for the sequential and co-operative nature of ribosome assembly. As an approach to this problem, we have taken advantage of the temperature dependence of in vitro reconstitution and have used chemical probing methods to examine the conformation and reactivity of 16 S rRNA at successive stages during subunit assembly. One class of nucleotides displays reactivities similar to those observed in native 30 S particles when the RNA and protein are incubated in the absence of any heat step (0 degrees C effects).

Molecular basis of tetracycline action: identification of analogs whose primary target is not the bacterial ribosome.

Tetracycline analogs fell into two classes on the basis of their mode of action. Tetracycline, chlortetracycline, minocycline, doxycycline, and 6-demethyl-6-deoxytetracycline inhibited cell-free translation directed by either Escherichia coli or Bacillus subtilis extracts. A second class of analogs tested, including chelocardin, anhydrotetracycline, 6-thiatetracycline, anhydrochlortetracycline, and 4-epi-anhydrochlortetracycline, failed to inhibit protein synthesis in vitro or were very poor inhibitors.