High impact information on POB3

• Spt16 functions as a component of the yeast CP (Cdc68/Pob3) and mammalian FACT (facilitates chromatin transcription) complexes, which are involved in transcription elongation and DNA replication [1].
• The previously uncharacterized Pob3 sequence has significant amino acid sequence similarity with an HMG1-like protein from vertebrates [2].
• Mutations in POB3, but not in NHP6A/B, also display strong synthetic defects with hir/hpc mutations [3].
• Mutation of the S phase checkpoint gene MEC1 caused pob3 mutants to lose viability rapidly under restrictive conditions, revealing defects in a process monitored by Mec1 [4].
• Direct examination of DNA contents by flow cytometry showed that S phase onset and progression were delayed when POB3 was mutated [4].

Biological context of POB3

• Yeast Spt16/Cdc68 and Pob3 form a heterodimer that acts in both DNA replication and transcription [5].
• The CP components Cdc68 and Pob3 closely resemble the FACT components, except that the C-terminal high-mobility group (HMG) box domain of SSRP1 is not found in the yeast homolog Pob3 [6].
• Characterization of the CP complex, an abundant dimer of Cdc68 and Pob3 proteins that regulates yeast transcriptional activation and chromatin repression [7].
• This dimer of Cdc68 with Pob3 is stable to partial purification, so that the functions of gene activation and repression that are assigned to Cdc68 are likely to be properties of the CP complex [7].

Associations of POB3 with chemical compounds

• Nhp6 interacts with Spt16/Pob3, the yeast equivalent of the FACT elongation complex, consistent with nhp6ab cells being extremely sensitive to 6-azauracil (6-AU) [8].

Other interactions of POB3

• These results suggest that Spt16-Pob3 and Nhp6 cooperate to function as a novel nucleosome reorganizing factor [5].
• Spt16, Pob3, and Pol1 proteins were all found to localize to the nucleus in S. cerevisiae [9].

References