Polycomb group (PCG) gene mutants cause ectopic expression of Antennapedia (Antp) and other homeotic genes. The PCG protein encoded by the PgG gene has a domain that binds to methylated histone H3. This finding supports which of the following hypotheses? a) that PCG mutants lack Antp mRNA compared to the wildtype
b) that PCG repress transcription by interacting with chromatin
c) that PCG binds to Antp genes and serves as a transcription activator
d) that PCG activates Antp genes in tissues
e) that PCG is allosteric activator of RNA polymerase II

b) that PCG repress transcription by interacting with chromatin

Explanation:

The Polycomb-group (PcG) proteins are evolutionarily conserved proteins in all higher eukaryotes which are involved in establishing epigenetic silencing of developmental genes. In animals, the PcG proteins are well known to form complexes capable of silencing target developmental genes by modulating chromatin structure during embryo development. In Drosophila melanogaster, the Polycomb repressive complex 2 (PRC2) is known to catalyze the trimethylation of lysine 27 on histone H3 (i.e., H3K27me3), thereby silencing homeotic (Hox) developmental genes. The core of the Drosophila PRC2 complex is composed of Enhancer of zeste [E(​z)], Suppressor of zeste 12 [Su(z)12], and Extra sex combs (Esc) proteins. The E(​z) protein is a well-known histone methyltransferase that maintains the methylation status of Hox genes, thereby silencing their expression during embryo development.

the answer to this question is a